20.

1 Historical Outline
Awareness of the influence of work conditions on human health has its
beginnings
in antiquity. The first mentions of the subject are found in the ancient
Egyptian encyclopaedia dating back to 1800 bc. Descriptions of pain and
injuries
of the spine in pyramid builders are found in Egyptian papyruses. Hippocrates
(460–377 bc.) in his treatise Airs, Waters and Places described symptoms that
occurred in workers extracting nonferrous metal ores. In this treatise he
explicitly
stressed the need to observe the patient in his or her work environment,
including identifying work environment conditions as risk factors of many
diseases
(Gochfeld 2005).
The first observations of diseases in miners were described by Agricola (Georg
Bauer; 1494–1555) and Paracelsus (1493–1541). In his book On the Nature of
Metals,
Agricola described diseases affecting metal ore miners in Bohemia. In his
monograph
on occupational diseases, Paracelsus presented a similar problem in miners
of gold, silver,
and other metals in the region of Villach in Austria. In his treatise
Twelve Books on Mining and Smelting (1557), Agricola described a number of
aspects of mining, smelting, and refining of gold and silver. He also advocated
the
use of ventilation and personal protective equipment such as leather shoes
and gloves
and loose veils to protect the miners from dust (Gochfeld 2005).

Bernardino Ramazzini (1633–1714), a professor of medicine at Modena and

Padua, pioneered scientific research in the areas of occupational hygiene and
medicine. He is regarded as the father of occupational medicine because of
his
masterpiece on occupational diseases entitled Diseases of Workers. The
quintessence
of Ramazzini’s school is his advice to doctors, which was ‘To the questions
recommended
by Hippocrates, he should ask one more—What is your occupation?’
(Gochfeld 2005). Ramazzini presented a comprehensive approach to workers’
health
problems, embracing epidemiology, hygiene, and certain aspects of
ergonomics. His
areas of interest covered many occupational groups, 69 of which he described
in his
works, including miners, apothecaries, locksmiths, glaziers, painters, mirror
manufacturers,
tanners, and bakers (Zanchin 2005).
In Poland, Wojciech Oczko, in his treatise entitled Attribute (1581), pointed
out the occurrence of skin lesions caused by unhygienic work conditions. The
treatise About Sex and Venereal Diseases by Wojciech Szeliga, published in
1584 and translated into Polish, is considered the first textbook on toxicology.
Leopold Lafontaine (1756–1812) promoted Ramazzini’s scientific ideas in
Poland.
His monograph Studies on the Diseases of Artists and Craftsmen dealt with
the
causes of and ways to prevent occupational diseases in various groups of
craftsmen
(Marek 2006).
The first institutions dealing with the protection of workers’ health were
established
at the turn of twentieth century. In 1898, Great Britain appointed the first
medical
factory inspector, Thomas Morison Legge (1863–1932; Waldron 2004). In the
twentieth century, research progress in the field of occupational pathology,
epidemiology
and toxicology contributed significantly to the advancement of occupational
hygiene and medicine. Achievements in these disciplines led to the
implementation
of practical solutions for the protection of workers’ health.
In the 1920s, the first lists of occupational disease were developed, making it
possible
for workers to obtain compensation for work-related health impairment. This
process was preceded by the establishment of the International Labour
Organization
(ILO) convention in 1925, which included the first list of occupational diseases
and
toxic substances and the types of industry and manufacturing processes that
could
give rise to occupational diseases (Convention 18, 1925).
Although human heath has been threatened by harmful factors since the
dawn
of mankind, only much later did people become aware of risks related to work
conditions. The second half of the twentieth century saw significant progress
in
occupational medicine, along with the tempestuous development of industry
and
the introduction of new production technologies, machines and work tools,
automation,
chemicalisation of agriculture and, most recently, informatics and
computerisation.
New harmful factors whose health effects were not known before
began to emerge, as well as psychosocial factors resulting from work
organisation
and the mechanisation and automation of production processes. Their effects
were connected with the time pressures and increased mental stress.
Psychosocial
effects are no longer confined to the workplace environment but are carried
over to
the external environment and probably modify the incidence and course of
some
chronic diseases.

20.2 I dentification of an Occupational Disease

and a Rationale for Diagnosis
Occupational disease is a medical-legal term. In order to label a disease
occupational,
the causal relationship of the disease with work conditions must be
established and
the disease must be included in the list of occupational diseases. The latter is
a prerequisite
for obtaining the benefits stipulated in relevant legal regulations.
The probability of various occupational diseases having a causal relationship
with
work conditions is differentiated. The definition of occupational disease
requires this
relationship to be indisputable or highly probable. For some diseases, the
causal relationship
with work conditions may be established with almost absolute certainty, for
example, pneumoconiosis and a majority of acute or chronic poisons. Another
group
lists diseases for which occupational exposure is the most probable causal
factor, for
example, hearing loss in persons exposed to noise exceeding the permissible
level
over a long period of time or vibration syndrome in persons exposed to
mechanical
vibration. In these cases, occupational disease certification requires only high
probability and not certainty because the symptoms of the disease are not
absolutely
specific, that is, similar symptoms sometimes result from causes other than
exposure
to noise or vibration.
However, there are diseases recognised as occupational for which the degree
of
probability that occupational exposure causes the disease cannot be defined
as high.
Chronic bronchitis is a good example; under prescribed conditions in
accordance
with the Polish list of occupational diseases, it may be recognised as
occupational.
Medical certification in such cases is extremely difficult because the causes of
the
disease are complex and tobacco smoking is the dominant factor. For this
reason,
only about one-fourth of countries regard chronic bronchitis as an
occupational disease.
The European Union included this disease in their 2003 revised list, but limited
it to only miners working in underground coal mines.
According to ILO Convention no. 121 of 1964, each country may employ any of
the following procedures to regulate issues connected with occupational
diseases:
A procedure involving a list of diseases, including at • least the diseases
enumerated
in Schedule I of the convention
• A general procedure involving a broad definition of occupational diseases
• A mixed procedure that is a combination of the two above-mentioned
methods
Most countries have their own lists of occupational diseases; in Europe, only
two
countries—Sweden and the Netherlands—have no such lists. In these
countries,
each case of suspected occupational disease is assessed on an individual
basis. Such
a solution may create a problem by allowing discretion in decision making by
different
teams medically certifying similar cases.
When considering occupational diseases contingent upon multiple causes, the
inability to exclude an occupational cause cannot be a decisive factor in
favour of diagnosing
a disease as occupational; the rule of prevailing probability must be followed.
Occupational diseases must be diagnosed based on definite criteria that
consider
many factors in order to justify the causal relationship between the disease
and occupational
exposure (Marek 2001). The most important criteria are as follows:
Symptoms must correspond to the clinical presentation • of the disease in
question. The extent of diagnostic difficulties varies depending on the
specificity
of symptoms of the given disease.
• The occupational exposure level must be high enough. This is determined
based on the characteristics of harmful factors such as concentration,
intensity,
and length of exposure. When permissible values for these factors are
exceeded, the health risk for the worker increases accordingly.
When assessing occupational exposure to diagnose an occupational disease, a
number
of aspects should be considered:
• Chemical and physical factors: Type of factor, concentration level or
intensity (when compared to the maximum admissible concentration
or maximum admissible intensity), and the duration of occupational
exposure.
• Biological factors: Type of and duration of contact with the factor and the
mechanism of its effects or dissemination paths. It is not necessary to
determine
the concentration.
• Sensitising factors (allergens): Type of factor and an ability to determine
that the contact took place during work and that the factor was present in
the environment, raw materials, or semifinished or finished products. It is
not necessary to determine the concentration.
• Manner in which the work is performed: Degree and type of physical load
(static, dynamic, repetitive) and timing of activities that could impose
excessive
load on certain organs or systems of the human body.
Regardless of the principal method for assessing occupational exposure, there
are
situations in which such methods might not be sufficient. The assessment
might be
incorrect when the worker often moves between workstations with different
levels
of hazard or different routes of poison absorption, especially through the skin
or in
which they perform jobs involving physical strain or in hot microclimates.
These
factors cause increased lung ventilation and dose absorption, and use of
personal
protective equipment and nonobservance of occupational health principles
can cause
incorrect assessment. In such instances, the ‘biological monitoring’ process
can
be used, which involves measuring the concentration of toxic substances or
their
metabolites in the blood or urine. For some toxic substances, reference values
in
nonexposed people and biological exposure indexes that are considered safe
are
determined.
When diagnosing a disease, the evaluating doctor should always obtain the
necessary
data on the worker’s level of exposure and his or her medical history from the
employer and/or the organisation’s preventive health care doctor. It should be
noted
that this information might be different and should be treated with caution.
Occupational Diseases 407
Some diseases manifest after a latency period. • The length of the latency
period is important for correct diagnosis. Due to the fact that the disease
manifests after exposure has ceased, long latency periods occur with diseases
such as cancers and pneumoconiosis.
• A differential diagnosis should be performed in each case. This is especially
important for diseases that can be effectively treated and are diagnosed
as occupational.
20.3 E pidemiology of Occupational Diseases
Poland has an established system of registering incidences of occupational
diseases.
Sanitary and epidemiological stations report each new case of a recognised
occupational
disease to the Central Register of Occupational Diseases at the Nofer Institute
of Occupational Medicine in Lodz, where a database on occupational diseases,
compiled
since 1971, is in use. The register annually publishes a bulletin on the
incidence
of occupational diseases, which contains the number of new cases of
occupational
diseases classified according to the number of items assigned to it in a list of
occupational
diseases, age, sex, national economy sector, and province. In addition to the
absolute incidence, the bulletin contains the incidence rate per 100,000
employed.
Thus, Poland fulfils the recommendations of the European Commission
regarding
the maintenance of statistics on occupational disease incidence in member
states.
For many years, the annual number of new cases of occupational diseases has
stabilised
at a level of approximately 10,000–12,000 per 100,000, and a slight upward
tendency was observed. In 1999, this trend collapsed and by 2006 the number
of new
cases plunged more than threefold. This downward trend ceased in 2007
when the
incidence rate rose by 156 cases (Table 20.1).

Tabel 20.1

Such a sudden steep decrease in incidence is not possible without the

interference
of disturbing factors and therefore should be examined. The Institute of
Occupational
Medicine and Environmental Health in Sosnowiec drew the following
conclusions
from a detailed 2004 analysis (Marek and Kłopotowski 2004):
Statistics on occupational diseases in Poland are subject • to errors resulting
from underestimation and overestimation of some diseases, caused largely
by insufficient or incorrect diagnoses by the primary occupational health
services.
• Preventive health care doctors are not inclined to refer affected workers to
institutions that can diagnose occupational diseases for fear of incurring
additional costs.
• Workers themselves are less motivated to apply for a certification of
occupational
disease and often preferred to continue in their existing jobs.
• It is unlikely that an improvement in work conditions was significant enough
to justify the drastic fall in the incidence of occupational diseases.
• Many chronic occupational diseases like pneumoconioses, hearing loss,
diseases of the vocal organs, and vibration syndrome develop after prolonged
exposure. They appear after many years of cumulative exposure and
are not a result of a current or recent situation.
• A decrease in national employment cannot significantly reduce the number
of new cases of recognised occupational diseases, because the number is
calculated based on the incidence rate per 100,000 employed.
• The influence of changes to the list of occupational diseases can also be
excluded because the changes actually came into force in 2004 while the
downward trend in the number of new cases began in 1999.
• The likelihood of errors in the data entered into the system of the Central
Register of Occupational Diseases can also be excluded. The system is
highly secure, and it can be assumed that all cases are certified by sanitary
inspectors and are included in the register.
In conclusion, officials expressed concern that the fall in the incidence of
occupational
diseases from 1999 to 2000 was not realistic and could not be treated as a
positive development. There was a justified concern that a substantial number
of
occupational diseases were not recognised and/or reported. The rise in the
number of
cases reported last year might be a sign that this worrying trend will reverse.
There are seven occupational diseases in Poland that constitute over 85% of
the
general incidence (Szeszenia-Dabrowska and Wilczy´nska 2007). From 1999
to 2000,
some of them, such as chronic diseases of the vocal organs, noise-induced
hearing
loss, and skin diseases, showed a clear downward trend. Other diseases, such
as pneumoconioses,
maintained similar levels. The number of certified infectious or parasitic
diseases increased (Table 20.2). Chronic diseases of the vocal organs mostly
affected
teachers; the high numbers of incidence in previous years were
overestimated.
Pneumoconioses ranked second in the profile mentioned above and in 2007
accounted for 21% of the total number of occupational diseases. Coal miner’s
pneumoconiosis
was dominant, accounting for about 70% of the cases. Moreover,

Tabel 20.2
105 cases of asbestosis and 90 cases of silicosis were recognised, and
evidence exists
that the number of pneumoconiosis incidences was underestimated.
Infectious or parasitic diseases rank third in the list with borreliosis accounting
for 60% of this type of disease. Viral hepatitis, which was prevalent for many
years,
now accounts for about one-fourth of this group. Hepatitis B, persisting mainly
in
health care personnel, was most common for many years. At present,
hepatitis C is
the most prevalent type and is 2.5 times more common than hepatitis B. This
is the
result of effective prophylaxis for hepatitis B, that is, widespread use of
disposable
syringes and needles as well as preventive vaccinations.
A clear, almost threefold decrease in cases of hearing loss in the last five
years is
probably also the result of better medical prophylaxis. Workers showing
audiometric
hearing loss close to the criterion for diagnosing an occupational disease must
discontinue
exposure to noise.
Skin diseases are probably underestimated, as they rank high in many
European
countries.
An increasing frequency of diagnosis of diseases of the peripheral nervous
system
is mainly due to carpal tunnel syndrome from the way in which a job is
performed.
The rate of diagnosis of work-related cancers is probably greatly
underestimated.
About 10% of cancers develop as a consequence of occupational exposure,
but in
Poland as few as 100 cases a year are diagnosed as occupational. The long
latency
period is the main cause for this underdiagnosis. Due to the latency period,
the peak
incidence of cancer is found in retirees after their occupational activity has
stopped.
The incidence of disease in this group is not actively monitored and often
remains
undiagnosed.
Statistical data on the prevalence of occupational diseases in Poland, although
based on a reliable registration of cases reported by sanitary inspectors, are
distorted

by errors of underestimation or, to a lesser degree, overestimation, and

therefore
require a critical evaluation.
Certain positive phenomena have been noted over the last 20 years. The
number
of acute and chronic poisoning cases has decreased considerably. Severe
poisoning
cases rarely occur. There have been no epidemics of acute poisoning with
benzene
and carbon disulphide, as had occurred in the past. The frequency of heavy
metal
poisoning decreased radically and only single cases have been noted recently.
Not a
single incidence of anaemia and saturnine colic has been observed.
Pneumoconioses
are now diagnosed in their early phase and cases of tumoural pneumoconiosis
among
workers occur only as exceptions.
In Poland, as in other countries, statistics on occupational diseases cover only
incidence, whereas prevalence, that is, the actual number of sick people, is
not
known. This number can be estimated based on the assumption that a great
majority
(about 70%) of occupational diseases diagnosed each year cause irreversible
health
damage, and the average life expectancy after diagnosis is 15 years.
According to
this estimate, about 80,000 people in Poland are affected by an occupational
disease.
This number is as big as the population of a large town, which shows that
occupational
diseases are a serious problem and have health, social, and economic effects.
Occupational disease is especially important because it is due to unsafe work
conditions
and neglect in prevention.
20.4 W ork-Related Diseases
The adverse effects of work conditions on the health of working people are not
limited
to disorders relating to classic occupational diseases in the medical and legal
sense. Unsafe and harmful work conditions may contribute to the
development of
some chronic diseases that are very common in the general population.
English terminology
uses the term ‘work-related diseases’ and in Poland the term employed is
‘paraoccupational diseases’. They are defined as diseases of a multifactorial
aetiology
in which work conditions are one of several risk factors that affect the
manifestation
or aggravation of the disease.
In Poland and in many other countries, work-related diseases are not officially
registered and are not eligible for compensation. The role of work conditions in
the
aetiology of these diseases is the subject of extensive research the world over.
The
importance of work-related diseases was recently highlighted as more
significant
than classic occupational diseases.
A group of experts from the World Health Organisation (WHO) in Geneva
prepared
a detailed report in 1985 on the problem of work-related diseases. The
recommendations
of the report, including proposals for dealing with diseases considered
work-related, remain a live issue even today. The experts proposed inclusion
of the
diseases outlined in Sections 20.4.1 through 20.4.5.
20.4.1 B ehavioural Responses and Psychosomatic Illnesses
The risk factors for psychosomatic diseases that are mentioned in the report
include
work overload, monotonous work, shift work, migration (working abroad), and

performing a managerial role in an organisation. Different types of mental

disorders
may lead to depressive reactions, hypertension, and peptic ulcer disease.
Increased
job-related tension and anxiety encourage smoking and alcoholism.
20.4.2 H ypertension
The acute effects of stress on increases in blood pressure are well-proven.
There
is less convincing evidence that repetitive situations, noise, vibration, and
adverse
microclimates can influence the development of hypertension.
20.4.3 I schaemic Heart Disease
Studies have shown that acute coronary events are linked to stress, work
overload,
holding two jobs, and working overtime.
20.4.4 C hronic Nonspecific Respiratory Diseases
This class mainly relates to the effects of dust and aerosol contaminants
present
in the workplace on the development of chronic bronchitis. A number of
studies
reveal the effects of exposure to contaminants, mainly organic dusts and
sulphur
disulphide, on the development and course of this multiple-factor disease.
However,
there is no doubt that smoking is the main causal factor and therefore only
about
one-fourth of all countries in the world, including Poland, have added chronic
bronchitis
to the list of occupational diseases, and only provided that certain conditions
are fulfilled. Moreover, the European Union introduced chronic bronchitis into
the
European Schedule of Occupational Diseases in 2003, but it only applies to
miners
working in underground coal mines. Therefore, chronic bronchitis in some
countries
may be considered an occupational disease when certain conditions are
fulfilled, but
in other countries it remains a work-related disease.
20.4.5 L ocomotor Disorders
Locomotor disorders are frequently encountered in people of different age
groups.
These are multiple-factor pain syndromes and result from such risk factors as
degenerative,
inflammatory, traumatic, and neoplastic disorders. Evidence shows that
some may be work-related. WHO experts selected two syndromes they
consider
work-related, namely lower back pain and shoulder and neck pain syndrome,
for
addition to the list.
Lower-back disorders are associated with occupational work involving risk
factors
such as forced body posture, frequent bending and twisting, lifting heavy
objects,
and exposure to general vibrations. They are found in jobs such as dock
workers,
miners, nurses, agricultural machine drivers, and heavy equipment operators.
Shoulder and neck pain syndrome is significantly more frequent in workers
who
perform work with their hands above shoulder level for prolonged periods.
Despite
arguments for the work-relatedness of locomotor disorders, a majority of
countries,
including Poland, do not include them in their lists of occupational diseases.

The European Union also decided not to include them in the new version of
European
Schedule.
Because of their complex and multifactorial aetiology, occupational diseases
are
still the subject of intensive epidemiological studies. These studies aim at,
among
other things, determining the probable degree of the causal relationship
between recognised
disorders and occupational exposure by using appropriate statistical methods.
A demonstration of partly occupational aetiology is more difficult due to the
lesser
impact of the occupational factor among the possible causes of the disease.
This
share, called the etiological fraction (EF) is calculated using the following
formula:
EF
RR 1
RR
( −)
where EF is the etiological fraction and RR is the relative risk rate.
Example 1
Epidemiological studies have found that chronic bronchitis is four times more
common in workers exposed to dust at the workplace than in a control group
of nonexposed persons. The relative risk rate (RR) = 4. Entering this rate into the
formula obtains the following result:
EF
41
4
75 ( )
%
−
The EF of the occupational exposure is high, at 75%. In this example, chronic
bronchitis fulfils the criteria for an occupational disease.
Example 2
Epidemiological studies have found that lower-back disorders are two times more
common in miners than in the control group, with an RR of 2. Entering this into
the formula obtains the following result:
EF
21
5
50 ( −)
In this example, the share (fraction) of the occupational exposure is lower and
does not reach the prevailing probability level. The criterion for an occupational
disease is not met, but the condition could be a work-related disease.
The above formula may be applied if the shares of other etiological factors are
evenly distributed over both groups under consideration.
Progress in epidemiological studies and the advancement of research methods
may
lead to the conclusion that some work-related diseases meet the criteria to be
occupational
diseases and should be introduced into the schedule of occupational diseases.
This process will be very difficult, because diseases considered work-related
are also very common in the general population. Their aetiology has multiple
factors and
there are no clinical criteria to distinguish between occupational and
nonoccupational
natures of these diseases.
20.5 P revention of Occupational Diseases
Civilised countries all over the world are engaged in multidirectional activities
created
to limit the incidence rate of occupational diseases. The WHO, highlighting the
need to protect the health of working people, described its aim as ‘achieving a
state
in which the level of general morbidity of different occupational groups will not
exceed the level of morbidity of the general population’.
This rule has not yet been fully realised in any country, and the effectiveness
of
occupational disease prevention varies from country to country. Employers,
health
care services and, to a great extent, the workers themselves must take the
necessary
preventive actions. There are three types of prevention:
1. Primary prevention
2. Organisational prevention
3. Medical prevention
Primary prevention, or technical prevention, aims to ensure safe work
conditions
and is the task of engineers and technicians. Primary prevention starts at the
design
stage for machines, equipment, and production technologies. Design defects
in technologies
are very difficult to eliminate once production has started. It is essential
to involve a health care physician at the design stage who can assess health
risks
arising from the introduction of new technologies. In many branches of the
national
economy, workers are exposed to different harmful or noxious factors. The
employer
must ensure that these factors are restricted to the limits permitted by
hygienic
norms. This can be achieved through solutions such as hermetising production
processes,
using local exhaust ventilation and general ventilation at the workplace, and
replacing high-risk technologies with safer ones.
Personal protective equipment such as protective clothing, masks, ear
protectors,
goggles, and gloves may be placed at the border of technical and medical
prevention.
However, some protective gear reduces work comfort and can be used for
limited
durations only. A better solution may be to give up high efficiency in favour of
work comfort. Disposable masks used in mining are an example; their
efficiency is
assessed at 50%, but they are tolerated in underground mining conditions.
Organisational prevention in high-risk conditions and rotating jobs can reduce
health risk by shortening working time and lengthening total employment
time.
The benefits obtained result not only from shortening the time of exposure,
but also
facilitate the processes of disturbed defence mechanisms, such as eliminating
dust
from the respiratory tract or detoxification processes. Moreover,
organisational prevention
tasks involve appropriate arrangements for shift work and work involving
great physical effort. These aim to ensure the protection of older employees
suffering
from a chronic disease. This type of prevention is particularly difficult and
requires
the cooperation of employers and occupational medicine services. Medical
prevention involves a broadly understood protection of the workers’
health at the workplace. The main task of doctors of occupational medicine is
to
conduct prophylactic examinations—preplacement, periodic checkups, and
control.
Preplacement examinations cover newly hired employees or those transferred
from
another post and should detect any health contraindications. Periodic
examinations
systematically check the employees’ health status and assess their fitness for
the job.
They are particularly helpful in detecting the health effects of exposure to
harmful
and noxious factors at as early a stage as possible. Periodic examinations also
detect
diseases not associated with work that appear during employment and which
may
constitute a contraindication to work at the present job.
All employees on return from a sick leave exceeding 30 days should be
subject to
control examinations which are intended to obtain a medical opinion on
whether the
sickness has caused a reduction in their ability to work.
Preventive examinations also provide guidance regarding treatment of
occupational
or other work-related diseases. A doctor of occupational medicine overseeing
the preventive health care of workers should be acquainted with the positions
and
concomitant health hazards. He or she should prepare a detailed plan for
preventive
examinations, identify the groups of workers exposed to particular hazards,
and classify them according to sex, age, and length of employment. The
employer
should provide data on exposure levels, results of concentration
measurements and
the intensities of harmful factors, any record of exceeding exposure limits, and
information
on daily working hours, shift work, and overtime work.
Doctors of occupational medicine are involved in a number of other tasks
apart from
preventive examinations, such as propagating health and rehabilitation
programmes
and medical education, ensuring observance of personal hygiene principles
and wellorganised
rest and leisure time, and providing first aid in cases of emergency.
In order to prevent occupational diseases, it is very important that the
employer
inform employees about the conditions in the work environment, the potential
effects of exposure to these conditions, and the ergonomic principles of safe
work.
An employee should know what his or her workstation should look like, so that
he
or she can ask for modifications from the employer. Worker training should be
conducted
in the form of lectures and practical training at workstations (Dawydzik 1997
and Ordinances of 1996, 2002, 2002).
20.6 Foreseen Directions of Ch anges in Occupational
Disease Incidence in Poland
The prevalence of occupational diseases and their clinical forms have been
closely
associated with the following:
Development of i • ndustry and technologies
• Work conditions
• Work organisation
• Introduction of new substances and theoretical knowledge about their effect
on the human body
• Development of health and safety

The development of new technologies and the related changes in work

conditions and
practices change the workload level and types of occupational hazards. This is
caused
mostly by changes in the structure of the economy, manifested by marked
transfer
of workforce to the services sector, more developed technologies that
increase the
automation of many workstations, and the introduction of computer
technologies.
The use of computer systems in production processes and services, as well as
competition
on the free market which forces an increase in productivity, are causes of
increased mental stress due to a multitude of incoming information and a
need to take
responsibility for actions.
Together with improvements in technical and medical prevention, these
changes
allow hope that the future will see reductions in the incidence rate, structure,
and
degree of severity of occupational diseases. Progress in technical and medical
prevention
as well as partial elimination of the most dangerous poisons will bring about
further decreases in the number of occupational poisoning incidents,
especially
severe ones. Improvements in medical prevention will lead to a reduction in
the
number of occupational hearing loss cases. Progress in the prevention of viral
hepatitis,
mostly of type B and, to a lesser degree, of type C is another factor that will
contribute to the decrease in incidence rate. Assessment of the future
incidence rate
of borreliosis is difficult, because at present there is no vaccine and it is not
certain
that it will become available in the future.
Improved diagnostic criteria and progress in prevention involving voice
production
education will decrease the rate of diagnosis for diseases of voice organs.
There are, however, indications that incidence rate of some diseases will grow
due
to advancement in diagnostic capabilities. Compared to the statistics of other
countries,
the incidence in Poland of occupational skin diseases and allergic diseases,
especially occupational asthma, is underestimated. Poland may also see an
increase
in the incidence rate of locomotor system disorders, especially in those who
work
with computers.
Introducing effective medical prevention methods might cause a temporary
increase in the number of cases of pneumoconiosis diagnosed. In the long
term, the
incidence rate will decrease due to advancements in reducing dust levels at
workplaces,
mainly in mining. The number of diagnosed occupational cancers is certainly
underestimated, and not only in Poland. The number of diagnosed cases may
be expected to rise, considering the long latency period of cancer.
There are many arguments that occupational work does not always have a
negative
effect on human health, and is in fact often a factor that promotes health.
However,
this approach to the effects of occupational work on health has not been the
subject
of many studies, and should be undertaken in the future.
Shift Work
25.1 I ntroduction
Shift work has become an integral part of our lives. Society needs 24-hour
services
such as security, and in many industries, such as power engineering,
continuous
24-hour technological processes are necessary, including on Saturdays,
Sundays,
and holidays. Therefore, the number of employees in this service sector,
including
services rendered via the Internet, is continuously increasing. White-collar
workers,
such as bank or stock market employees, also work at night. Receptionists,
bakers, daily paper printers, road drivers, physicians, airline pilots, firemen,
and
policemen perform shift and night work. Sometimes, shift work at industrial
plants
becomes necessary due to the modernisation of production technologies
through the
implementation of new instrumentation. In such cases, economic
considerations and
attempts to achieve a quick return of the costs require a more intensive
exploitation
of the workforce and equipment.
The number of shift workers, including night workers, is continuously
increasing.
In the western European countries, one-fifth of employees work in shifts
(Harrington
2001).
For effective and safe shift work, the duration and time of the shift and the
employee’s working capacity should be adequately balanced based on the
circadian
rhythm of basic life processes. Due to a substantial physiological and social
burden,
both physical and mental workload should be adjusted to the time of work to
limit
the risk of errors being committed by shift and night workers, which may
result in
accidents. In the 1970s, French physician and ergonomist Pierre Cazamian
proposed
the term ‘chronoergonomics’ for the branch of ergonomics that applies
ergonomics
to the management of workers’ time (Ogin´ska 1991).
25.2 C ircadian Rh ythms of Human Ph ysiological
Functions and Th eir Significance for
Occupational Safety
25.2.1 C ircadian Oscillations of Physiological Functions
The human body contains structures that generate internal circadian rhythms,
which
are dependent on cyclic phenomena observed in the external environment,
such as
the day–night rhythm. These phenomena optimise body functions by adjusting
basic
life processes according to environmental time determinants including the
time of
the day (Figure 25.1).
For example, humans typically sleep during the night and are awake and
performing
activities during the day, because the ability to perform physical and mental
work
is maximal during the day. Many rhythmic processes occurring in the human
body
without our knowledge reach maximal intensity during the day; this is
confirmed
by scientific findings. Some rhythmic processes reach maximal intensity
during the
night.
The following processes have a 24-hour rhythmicity:
Physiological processes (heart rate, arterial blood • pressure [ABP], core
body temperature)
• Metabolic processes (hormone secretion, changes in blood chemical
composition,
synthesis of biochemical compounds in tissues and organs)
• Psychophysical processes (ability to perform mental work-related activities,
oculomotor coordination, sensitivity to acoustic and visual stimuli)
• Sensitivity to stress of different origins (disease-related stress, sensitivity
to pain)

Figure 25.1

The rhythmicity of biological processes depends on the human’s lifestyle and

internal
biological clock. These processes are in harmony in individuals who are active
during the day and rest during the night. For example, glucose metabolism
increases
upon awakening and further increases during the day, decreasing in the
evening.
The metabolism of fatty acids increases in the evening and at night during the
rest
phase and decreases near the end of sleep. There is a correlation between
biological
variables and general indicators of feelings, such as alertness and most
mental fitness
parameters. During the day, body temperature rises and increases the
adrenalin
serum concentration, which is optimal for well-being and alertness. In the
evening,
the adrenalin serum concentration and core body temperature decrease,
psychophysical
fitness deteriorates, and fatigue intensifies (Zuz˙ ewicz et al. 2001).
During night shift work, a reversed sleep–wake rhythm is forced instead of the
natural day–night rhythm, bringing about adverse health and social
consequences in
shift workers.
25.2.2 C ircadian Oscillations of Psychophysical Fitness
The ability to perform physical tasks depends on many biochemical and
physiological
parameters having circadian rhythms. Higher tolerance to physical tasks
during
the day compared to night is due to more intensive metabolism, the utilisation
of glucose,
and increased glycogen decomposition in muscles. Increased blood flow
results
in improved tissue oxygenation and excretion of metabolic products (CO2,
lactic acid, and so on). Faster breathing delivers a greater amount of oxygen
and results in faster
CO2 excretion. An increase in heart rate and ABP delivers a greater amount of
oxygen
and energy to the working muscles, brain, and other organs. Increased
perspiration
and dermal blood flow eliminate excess heat produced due to physical effort.
Mental efficiency is also dependent on circadian rhythmicity. Evaluations of
psychological
tests of mental efficiency (e.g. reaction time, oculomotor coordination,
concentration) indicate variations with a characteristic circadian profile.
Mental
efficiency increases on awakening and decreases in the evening. In many
people,
particularly the elderly, a transient decrease in mental efficiency occurs in the
early
afternoon. This is not a consequence of sleepiness after meal consumption,
but rather
an effect of intensifying fatigue after several hours of activity following the
moment
of awakening. There are some exceptions to this rule, for example tasks
requiring
substantial short-term memory input can be performed better at night, but the
durability
of the acquired knowledge is much shorter. Interestingly, the rhythm of
mental
efficiency is similar to the rhythm observed in the physiological parameters,
such as
core body temperature, heart rate, ABP, and adrenalin secretion (Figure 25.2).

25.2.3 Workability Rhythm

In individuals with typical patterns of circadian activity, overall work ability
increases from the moment of awakening until the afternoon hours, when
there is a
slight decrease between 1 and 3, or during the usual lunch time, regardless of
meal

Figure 2.5 .2

consumption. In the evening, work ability gradually decreases until the usual
time
of rest. After prolonged activity, there is minimal circadian rhythm in overall
body
efficiency between midnight and 4 am.
The circadian oscillations of work ability, especially physical work, are parallel
to
the circadian rhythm of the core body temperature, which under the normal
conditions
of the sleep–wake cycle reaches maximal values in the evening and minimal
values in the early morning.
Night shift work disturbs these relationships, and, if combined with sleep
deprivation
and fatigue, may significantly negatively affect the quality of work and
increase
the risk of committing an error.
25.3 D efinitions and Terms Related to Night Work *
The term ‘shift work’ is defined in international laws, particularly in directives
93/104/WE and 2003/88/WE. It refers to any form of shift work scheduling in
which
employees performing the same duties replace each other according to a
given work
schedule and that entails a need to work at different times during certain days
or
weeks. The term ‘shift worker’ refers to each employee whose work schedule
is part
of the shift work.
There are different systems for shift work in industry. They involve
occupational
activities lasting between 6 and 12 hours within the same shift. There may be
two, three,
or four shifts during a 24-hour period. The most frequently employed is the
three-shift
system, consisting of shifts starting at 6 am, 2 pm, and 10 pm, although there
may be
other systems as well and they may vary in rotation speed, the number of
consecutive
workdays on the same shift, or direction. Some shift workers work only night
shifts.
25.3.1 N ight Work
According to the Polish Labour Code (Section VI: Night work, Article 1517,
items 1
and 2), the term ‘night work’ refers to the 10-hour period between 9 pm and 7
am,
and a ‘night worker’ is defined as an employee whose working schedule has at
least
three night hours during a 24-hour period or at least one-fourth of the overall
working
time is at night.
This definition differs slightly from that found in international laws such as
convention
no. 171 MOP, recommendation no. 178 of June 1990 Night work, or UE
directive
2003/88/WE, referring to selected aspects of shift and night work. According
to these regulations, the term ‘nighttime’ refers to a period of time no shorter
than
7 hours including the hours between midnight and 5 am.
25.3.2 Work Constantly on the Move
The term ‘work constantly on the move’ refers to work that cannot be stopped
due to
the technology being used. This requires hiring three or four crews, working in
rotating
shifts, and providing uninterrupted 24-hour coverage every day and nigh

25.4 How Does Sh ift Work (Including Night

Work) Diff er from Daily Work?
Table 25.1 compares selected aspects of life activities in day and night shift
workers
that affect the quality of work performance and the health of the employees.

Tabel 25.1

25.5 C onsequences of Sh ift Work

Shift work may affect physiological functions, disturbing circadian rhythms
and
contributing to the development of some pathological disorders. Immediate
disturbances
of body functions caused by shift work include sleep disorders, chronic
fatigue, and digestive system ailments. These symptoms occur because of the
body’s
natural response to atypical work conditions, which are often of a short
duration and
connected with the work schedules, especially the night shift. They may be
relieved
by working day shifts or working longer intervals (Knutsson 2003). Shift
workers
often suffer from chronic ailments resulting from the lack of synchronisation of
their
internal body clock and a forced, atypical rhythm of activity and sleep.
Ailments due
to shift work are called ‘time debt syndrome’ or the syndrome of
maladjustment or
circadian disruption.
The mechanisms of exactly how shift work affects human health have not yet
been
fully explored. In healthy individuals who are active during the day, almost all
biological
functions, even at subcellular levels, have circadian rhythms that are related
to a constant sequence of the body’s maximal values. Even in isolated
parameters,
disturbance of these rhythms (such as the values of oscillation amplitude, the
time
shift of maximal value occurrence, or changes in the average circadian level)
may
bring about health-related consequences. Research indicates a relationship
between
night work and functional disorders of the digestive and cardiovascular
systems and
pregnancy abnormalities (van Mark et al. 2006). Since some diseases develop
slowly
and only manifest after many years, it is difficult to assess whether they are
caused
by disturbances of basic internal rhythmic life processes or they result from
external
reasons such as tobacco smoking, inadequate sleep, or inadequate nutrition.
Studies conducted so far have not determined the relationship between
increasing
sensitivity to various toxic substances used in production at different times of
the day
and the health-related problems in shift workers employed in different shift
systems.
The traditional approach to evaluation of occupational risk assumes that this
sensitivity
is the same at different times in a 24-hour period. Toxicological studies using
animal models indicate that there are different levels of risk depending of the
time of
the day that the worker is exposed to the adverse factors.
25.5.1 P hysiological Consequences of Shift Work—Shift Lag
Basic physiological consequences of night shift work include circadian
rhythmicity
disorders. Performing occupational activities at night, the usual time for sleep,
results in characteristic symptoms with different degrees of intensity, called
‘shift
lag’. Shift lag results when the body rhythm does not adjust to changes in
activity
time or the disturbance of the normal relationships between different rhythms
as a
consequence of shift work. The symptoms most frequently associated with
shift lag
include:
• Aggravation
• Sleep disorders
• Peristalsis disorders

Deterioration o • f oculomotor coordination

• Muscular strength impairment
• Disorders of distance and time perception
The relationship of the severity of circadian rhythmicity disorders to
occupational
activities at different times of the day depends to a large extent on work
scheduling.
Shift workers working in rotational shifts with a ‘backward rotation’ (i.e. the
sequence of shifts: morning, night, and then afternoon) and those constantly
working
night shifts experience the most substantial disturbances. Individuals working
in ‘forward rotating’ shifts with night work for two consecutive days and
morning
shift work that does not disturb the sleep period experience relatively less
substantial
disturbances (Pokorski and Costa 1998).
25.5.2 E ffect of Shift Work on Sleep
Sleep deprivation is a typical adverse effect of shift work. Overall sleep time
during a
24-hour period decreases and the quality of sleep deteriorates. Sleep
disorders in shift
workers result from the need to rest during the day, when there is an
increased noise
and light level and when most other people are active. Even experienced shift
workers
accustomed to resting during the day may experience some problems after
reaching
middle age because the quality of sleep deteriorates with age. Night workers
sleep
about 2–4 hours less than they would if they were day workers. Many night
workers
sleep after returning from work, that is, in the morning, when the majority of
people
are active after their night rest. A night worker should sleep several hours
before the
shift in order to feel less sleepy while working a consecutive night shift. This
means
splitting the usual sleep period into two parts that are shorter than a usual
night of
sleep. Even a short period of sleep may delay an accumulating feeling of
sleepiness
during the night shift. Sleeping a lot in the morning, without a nap before the
consecutive
working shift, may cause a substantial decrease in the worker’s
psychophysical
fitness at the shift end due to a long, over-16-hour period of continuous
activity.
Sleep problems are noted among shift workers more often than in other
occupational
groups, leading to more frequent use of hypnotic agents. Workers may
excessively
consume coffee or other caffeinated beverages and smoke tobacco. Such
behaviours
increase the risk of gastrointestinal or circulatory system disorders.
25.5.3 F atigue and Sleepiness
Fatigue is experienced at the end of a night shift by a large population of night
shift
workers and after many hours of daytime activity. Fatigue adversely affects
occupational
safety by impairing workers’ psychomotor fitness and causing, for example,
depression, irritation, and unjustified anger (Gaba and Howard 2002). The
effects of
sleep deprivation combined with prolonged activity are comparable to the
effects of
alcohol intoxication. Psychomotor performance decreases to a level
corresponding
to blood alcohol concentration of 0.5% after 17 hours of wakefulness (from 8
am
to 3 am), and to a level corresponding to blood alcohol concentration of 1.0%
after
24 hours of wakefulness (Dawson and Reid 1997).

25.5.4 S hift Work and Night Work–Related Stress

Night-work-related stress is defined as stress due to disturbances in the
natural
activity–sleep processes of the natural phases of circadian rhythms. The
disturbance
of circadian rhythms, sleep deprivation, sleep disorders, and fatigue are
typical
consequences of night shift work; they cause strain on workers that may
result
in a decrease in physical capacity, health disorders, worsened general
feelings, and
decreased performance. These disorders also increase the risk of errors and
accidents
(Figure 25.3). Stress is modified by many factors that are related not to the
work but
to the worker, including age, gender, educational background, and lifestyle.
The ability
to estimate risk level and to work out a problem-solving strategy, for example,
by
observing proper sleep and nutrition or by napping or other proper relaxation,
may
also play a role (Smith 1998).
Shift work is a stressor that may occur apart from other stressors associated
with
work performed at any time within a 24-hour period, such as lack of
autonomy,
monotonous activities, or environment and time constraints.
25.5.5 Health Consequences of Night Work
The summary health index by Haider et al. (1988) indicates a depleted state
of health
in shift and night workers when compared to daily workers performing
comparable
activities.

Figure 25.3

25.5.6 Digestive System Disorders

Disorders of normal digestive system functions and metabolism, such as
diarrhoea,
constipation, or heartburn, may occur more frequently in night shift workers
compared
to day workers. They result from improper nutrition, in terms of both the
food quality and the time of meal consumption. Irregular meal times interfere
with
the production of the hormones, acids, and enzymes necessary for food
digestion,
a diurnal function. Like other body rhythms, the digestive process slowly and
only
partly can become accustomed to an atypical activity–sleep pattern. Karlsson
et al.
(2001) carried out an analysis of metabolic disorders in a group of 27,000
workers.
The study indicated a higher prevalence of obesity, a low high-density
lipoprotein
cholesterol concentration, and a high triglyceride level in shift workers.
A report by Waterhouse et al. (1990) states that the risk of ulcerous stomach
and duodenum disease in night workers is two to five times higher than that of
day
workers. The development of pathological conditions can be observed 5–6
years
after beginning night shift work, which is much earlier than in day workers,
who
experience such disorders after 12–14 years. Chronic pathological conditions
of the
digestive system and ulcerous disease have been recently found to be caused
by
Helicobacter pylori. However, shift and night work are still considered risk
factors
for gastrointestinal tract disorders (Pokorski and Costa 1998).
25.5.7 C irculatory System Disorders
Many studies on estimating the risk of cardiovascular disorders among shift
workers
suggest that this population has an increased risk of coronary arterial disease,
arterial
hypertension, and myocardial infarction (Harrington 2001).
Knutsson et al. (1999) studied the relationship between shift work and
coronary
arterial disease. They compared the percentage of shift workers with coronary
arterial
disease in two groups of subjects. Each group consisted of 2000 patients with
a history of asymptomatic acute myocardial infarction. The study confirmed
the
relationship between shift work and an elevated risk of myocardial infarction
both
in women and men, but did not indicate any correlation between the level of
work-
related
fatigue, tobacco smoking, and educational background. The risk of circulatory
system disorders in shift or night workers is about 40% higher than that
observed
in day workers (Knutsson 2003). The risk increases with the duration of shift
work
and after 15–20 years of shift work. Circulatory system disorders of different
degrees
are observed in 20% of shift workers, three times more often than in day
workers
(Zuz˙ ewicz et al. 2001). The causes of cardiac disorders observed in shift
workers
include circadian rhythmicity disorders and the resultant changes in social life,
lack
of social support, stress, tobacco smoking, improper nutrition, excessive
coffee consumption,
and limited physical activity.
25.5.8 Disorders of Other Systems
Many studies confirm the effect of shift work on pregnancy. An increased risk
of
miscarriage, low body mass of the neonates, and premature labour are often
observed (Knutsson 2003) in pregnant shift workers. Menstrual cycle
irregularities more frequently
noted in female shift workers than in day workers may explain problems in
conceiving.
More attention has been paid recently to the prevalence of obstructive sleep
apnoea (OSA) syndrome, which is a pathological condition characterised by
shortlasting
periods of breathing obstruction, usually preceded by loud snoring. Although
OSA mainly affects male workers who usually drink alcohol before sleep, shift
and
night work is a risk factor for the development of this condition. Shift and night
workers affected by this condition experience excessive sleepiness during the
day.
Shift workers frequently report anxiety and depression symptoms. However, it
is
difficult to assess the range of the problem due to autoselection (the
employee’s decision
to quit the job) within this working population (Harrington 2001). Some reports
indicate that disorders defined as ‘anxiety or depression, requiring
psychotropic
agents for over 3 months or hospitalisation’ were diagnosed in 4% of daily
workers,
22% of shift workers working a three-shift system, and 64% of persons
working only
at night (Costa et al. 1981).
Shift workers with bronchial conditions may experience exacerbation of
symptoms
resulting from nighttime bronchial contraction. When night workers are
exposed to a
high concentration of dust or irritant substances, bronchial failure can
develop.
Shift work may prove especially adverse for individuals who take medications
regularly.
This is because the pharmacokinetic parameters are determined only for day
work for most medications. The same doses administered at night may have a
weaker
or stronger effect than those administered during the day (Zuz˙ ewicz et al.
2001).
25.5.9 S ocial Consequences of Shift Work
Some persons, especially young persons, decide to work shifts for family
reasons or
because they want to earn more, as night work is better paid. If both parents
are shift
workers, one may look after the children while the second one is at work. Shift
work
enables some people to look after old or ailing parents. However, workers
should consider
the accumulating effects of time debt syndrome. Sleep deficiency, a
continuous
feeling of fatigue and increased irritability, can contribute to the development
of family
conflicts. Excessive irritability makes interpersonal relations with workmates
and
closer acquaintances difficult, leading to isolation and feelings of loneliness,
especially
when the family does not understand the reason for such behaviour. Shift
workers are
divorced more frequently than their day-working counterparts. Rotating shifts
also
limit opportunities to participate in extra-occupational activities because
socialising
usually takes place during afternoon or evening hours. Social life is therefore
limited
among shift and night workers so that they can only socialise with other shift
workers
and their workmates. Shift work also limits active participation in political,
social,
and cultural events, which results in feeling more socially isolated over time.
25.5.10 S hift Work Tolerance
Studies estimate that one in five shift workers quits his or her job, generally
due to
poor tolerance to ever-changing timing of activities such as work, rest, and
sleep. Reasons for quitting shift work include age, family relations, lack of
social life,
health problems, and sleep disorders. Shift and night work intolerance
syndrome is a
series of relatively nonspecific ailments or symptoms resulting from a lack of
adaptation
to shift and night work for a long period of time (Pokorski and Costa 1998).
Only
about 10% of shift workers believe they tolerate such a working schedule
quite well,
do not experience the typical health disorders, and have a positive attitude
about the
system.
The symptoms of shift work intolerance observed in night workers include:
• Sleep disorders: Difficulty falling asleep despite fatigue and sleepiness,
poor quality of sleep, frequent awakening
• Persistent fatigue: Constant sleepiness after awakening or after rest on
nonworking
days, other than a physiological state of fatigue due to physical and
mental effort
• Changes in behaviour: Irritability for no specific reason, mood changes,
feelings of sickness or unsatisfactory performance
• Gastrointestinal tract disorders: Dyspepsia, pain in the upper abdomen,
exacerbation of ulcerous disease symptoms
• Use of medication: Need for regular use of hypnotic agents
Individual tolerance of shift work depends on gender, age, and personality
traits. One
trait that may affect night workers’ shift tolerance selection is their
chronotype, or
the time of day they are most alert and active. Although the workers with an
evening
chronotype better tolerate night work, they may experience more serious
problems
if they must work day shifts, particularly when they have to shorten their
usual sleep
period if the shift begins in the early morning hours. Better tolerance to shift
and
night work does not always result from many years of experience. In older
workers
with many years of service, tolerance to shift work actually deteriorates with
time so
that such workers can no longer tolerate their working schedule (Baker et al.
2004).
25.6 A ccident Risks during Sh ift Work
Errors committed at work during night shifts are usually due to workers’
inadequate
reactions. The main factors that cause accidents include sleep deprivation, a
momentary
loss of consciousness called ‘microsleep’, fatigue, and mood deterioration.
Most
errors committed during night work are harmful not only for the employees
themselves,
but also for the people they look after, especially in the health service and
transport fields. The main causes of errors committed by physicians during
their
duty hours are a 24-hour variability of fatigue and alertness, circadian
oscillations
of oculomotor coordination, circadian rhythms of mental performance, a
prolonged
working period, the effects of fatigue and sleep deprivation, and mental inertia
on
awakening after a short nap. When occupational activities require the
continuous
focus of attention in a monotonous environment, such as for road transport
drivers,
the occurrence of microsleep has a substantial probability of fatal errors.
From an occupational safety viewpoint, fatigue, sleepiness, and monotony
increase
the risk of overlooking warnings about the defects in technological processes
and
Shift Work 509
carry the risk of failure to respond or very slow responses to such events.
Examples
of such accidents include some widely reported catastrophes. The catastrophe
at the
atomic power plant on Three Mile Island (USA) occurred when workers did not
notice the warning that there had been a radiation release, which occurred at
about
4 am. One of the most tragic accidents was that at a pesticide factory in
Bhopal,
India, which happened around 12:40 am. One of the reported reasons of the
disaster
was insufficient workforce. A cloud of poisonous gas caused the deaths of
2500
people within 8 hours; the estimated number of victims was about 8000, and
even
10 years later, about 50,000 people suffer due to exposure to toxic gas
emissions. The
event with worst consequences for people and the environment was the
nuclear reactor
catastrophe at Chernobyl, Ukraine, which took place at 1:23 am (Smolensky
and
Lamberg 2000).
The probability of accidents and injuries increases even more during
consecutive
night shifts. The risk is higher during the second night shift by 6%, the third
night
shift by 17%, and during the fourth night shift by 36% (Folkard and Akerstedt
2004).
These data provide further evidence that only up to three consecutive night
shifts
should be included in a shift work schedule.
25.7 P revention of Adverse Eff ects of Sh ift Work
To prevent negative consequences of shift work, physical and mental
workload
should be adjusted to the workers’ psychophysical capacity, resulting from
circadian
oscillations of the body’s readiness to work. Implementing proper shift work
schedules,
observing rules that limit the effects of shift work on the physical and mental
health, and having concern for the overall wellness of shift workers will also
help
prevent negative consequences.
The following measures can be taken to limit the adverse effects of shift or
night
work:
Analysing and evaluating different shift work systems • to select the most
suitable system, ensuring the best tolerance to shift or night work, should
include the number of working hours, the number of consecutive days working
the same shift, the number of nonworking days, shift rotation (backward
or forward), multicrew systems, and the time of the shift start
• Identifying individual traits that condition the worker to tolerate the shift or
night work and working out the criteria of workforce selection
• Leading a proper lifestyle (proper sleep, naps, meals, active rest) to improve
tolerance to shift or night work, as well as propagation of such a lifestyle both
among shift or night workers and among their closest family members
• Improving the working schedule by optimising the time and length of
breaks and developing strategies to prevent sleepiness, particularly in night
workers, including preventing monotony at work
• Monitoring worker health, with particular attention to the increased risk of
certain diseases in shift and night workers
• Developing regulations concerning the timing of work and rest, health
protection
among shift and night workers, and bans on night work for particular groups at
risk, namely pregnant women and juvenile workers, with limits on
shift or night work for persons over age 45
Monitoring core body temperature during a 24-hour • period to determine
the most favourable shift system that will minimise the adverse effects of
shift and night work on health and general feelings of well-being (Knauth
et al. 1978)
The most favourable effect of limiting the negative consequences of
occupational
activity at night is preventing the ‘inversion’ of body temperature rhythm or
phase
shifts of other physiological and hormonal rhythms, as this disturbs their
reciprocal
relations and can cause time debt syndrome.
25.7.1 Work Scheduling
Night work should not be longer than 8 hours daily if the job is particularly
dangerous
or entails substantial physical or mental exertion (Labour Code, Article 151 7,
Sections 3 and 4). The employer and trade unions decide whether a given job
meets
the above criteria; when there are no trade unions, representatives of the
employees
make the decision. They are selected according to the procedure given by the
employer and following an evaluation by a physician who takes prophylactic
care of
the employees for the purpose of occupational safety and health protection.
Shift workers and workers constantly on the move have an additional
workload
apart from night work, namely working Sundays and holidays, which is allowed
based on Article 15110 of the Labour Code. Section 138, Article 1 of the Labour
Code provides information on the opportunities for extending working hours
when
the worker is constantly on the move: ‘When the work cannot be stopped due
to
production technology (work constantly on the move), a system of working
time can
be applied with acceptable working time prolongation up to 43 hours weekly
on average,
during the accounting period not exceeding four weeks or one day during
some
weeks; in these cases the daily number of working hours may be prolonged up
to 12
hours.’ However, this regulation should be applied with caution, given the
previous
reports on the adverse effects of shift work.
When the 8-hour workday is exceeded (regardless of the time of work), the
risk
of accidents rapidly increases during the ninth hour of work. The relative
accident
risk during the twelfth hour of work is more than twice as high as during the
eighth
hour (Vogel 2004).
Shift work is connected with stress and disturbance of circadian rhythms;
therefore,
the optimal shift work schedule provides a compromise between minor and
major
adverse effects resulting from stress and disturbed biorhythm phases.
Considering
the possibility of physiological and mental ‘adjustment’ to night work and the
need
to minimise health hazards and the effects of decreased physical capacity,
solutions
for work schedules should be based on the following suggestions:
• The number of consecutive night shifts should not exceed four (Knauth
1993).
• Shift rotation should always be in agreement with the normal course of a
day (morning, afternoon, night; Barton and Folkard 1993).

A system with quick shift rotation is more favourable than • a system

including
several consecutive days of working the same shift.
• A five-crew system is more favourable for shift work and work constantly
on the move, compared to a four-crew system (Lillqvist et al. 1997).
• Each shift should begin at a time that does not result in forced sleep
shortening
(e.g. morning shifts should not begin earlier than 6 am; Knauth
1993).
• Shift and night workers should work no longer than 8 hours, particularly
while working night shifts.
• While planning the workload, the employer should consider the natural
decrease in the psychophysical fitness of the worker between midnight
and 3 am.
• A physician should determine if the employees are fit or unfit for shift work
based on contraindications to shift and night work and predispositions
influencing long-term tolerance to this kind of work (Pokorski 1999).
• In the case of health-related problems or other contraindications, changes
to the working schedule should be made and a temporary withdrawal of the
employees from night work should be considered.
• Information about the adverse effects of shift work and ways to minimise
the risk connected with this kind of work should be well known among
managers, medical service, and occupational safety and health staff.
25.7.2 P redispositions and Contraindications for Shift Work
Employees considering shift work or night work should be aware of factors
that
can help them make an informed decision, for example, job satisfaction and
selfesteem.
They should ensure that they have the adaptive capabilities required for
shift or night work and should also be aware of the effects of this kind of work
on
family life.
Shift or night work is not recommended for persons with sleep disturbances or
circulatory or digestive system disorders because it may exacerbate disease
symptoms
and make treatment difficult. Contraindications for shift work also include
asthma, diabetes mellitus (especially insulin-dependent), and depression. Shift
workers should not abuse alcohol, stimulating substances (caffeinated
beverages), or
hypnotic agents, and they should limit tobacco smoking.
Night work is definitely contraindicated for pregnant women (Article 178 item
1 of the Labour Code) and juvenile employees (Article 203 of the Labour
Code).
For pregnant women, the employer must change the work schedule to enable
the
employee to perform work with no night hours, either by giving her another
job or by
exempting her from night work.
For juvenile employees, the strict ban on night work performance is due to the
disturbed
relationships between biorhythms, including disruption of the normal rhythm
of hormone production that leads to proper development of adolescent
individuals,
caused by night work. Ageing decreases the ability to adapt to atypical work
schedules,
so the World Health Organisation recommends using the three-shift system for
employees over 45.
512 Handbook of Occupational Safety and Health
Individuals who do not understand the physiological and psychosocial
consequences
of shift work may not consider the ways to minimise the adverse effects of
shift work on occupational health and safety when developing work schedules.
Close
cooperation between the persons responsible for work scheduling and the
employees
while developing work schedules, as well as making proper use of the
knowledge
on health hazards and occupational safety in shift workers (Baker et al. 2004),
will
improve the work scheduling processes.
Personal Protective
Equipment
26.1 L egal Status
Personal protective equipment (PPE) belongs to the group of protective
devices that
directly protect a worker against hazards in the work environment. Before
deciding
to use PPE, all possible technical and organisational measures to eliminate the
risk at
the source must be undertaken. When efforts to completely eliminate hazards
to life
and health or to reduce their admissible values do not succeed, that is, the
concentration
or intensity values of harmful factors present at workstations are still higher
than is permissible, the use of PPE is the final barrier for the worker.
European Union legislation has two areas of regulations. The first is included in
directive 89/656/EEC (1989) and determines the obligations of the employer
relating
to the safe use of PPE. The second area, included in directive 89/686/EEC
(1989),
covers the rules for placing these products on the internal market, that is,
assessment
of conformity to basic health and safety requirements.

26.2 R ules for Safe Use of Personal Protective Eq uipment

Ensuring the safe use of PPE is the duty of every employer, who should:
• Provide PPE free of charge.
• Select suitable PPE considering the nature and magnitude of hazards.
• Organise training on the appropriate use of PPE.
• Ensure appropriate storage, cleaning, disinfection, maintenance and
necessary
servicing for PPE.
The appropriate selection of PPE is fundamental. PPE should meet selection
criteria
that consider the hazards and work environment conditions and at the same
time conform
to the basic requirements of safety and ergonomics. Conformite Europeenne
(CE) markings as well as the manufacturer’s declaration and the instructions
for use
confirm the PPE’s conformity to regulations.
Before selecting the PPE, all hazards in the work environment should be
identified and occupational risk assessment should be carried out. The extent
of
dangerous and harmful factors should be measured, if necessary, and the
findings
compared with admissible values such as maximum admissible concentration
(MAC) for chemical factors and dusts or maximum admissible intensity for
physical factors, noise, vibration, and electromagnetic fields. The number of
times
an admissible value is exceeded will be the guideline for selecting the
protection
level. Knowledge about harmful factors activity will indicate the necessary
extent
of protection.
PPE can be categorised as follows, based on the scope of protection:
• Protective clothing
• Hand and foot protection
• Head protection
• Hearing protection
• Eye and face protection
• Respiratory protection
• Equipment protecting against falls from a height
The first stage of PPE selection is the analysis and assessment of hazards. A
technical
solution should then be based on additional information related to the
following:
• Workstation organisation
• Climatic conditions
• Additional hazards not related to the necessity to use PPE
• Characteristics of the user
• Working time and other conditions that could have adverse effects on a
worker’s health and well-being
The employer is responsible for determining the terms of use for PPE. While
determining
the terms of use, the level of hazard, and frequency of exposure to the hazard
the employer should consider workstation characteristics and the efficiency of
the
PPE. If more than one hazard occurs and the situation calls for use of more
than
one PPE, the equipment must be designed in such a way that it can be
adjusted without
reducing its protective properties. The employer is also responsible for
training,
information and consultations related to the safe use of PPE. Both the
employees
and the personnel responsible for supervising the use of PPE should be aware
of the
following:
The PPE’s p • rotective properties
• The consequences of not using the PPE
• How to use the PPE correctly
• How to keep the PPE clean and when it should be discarded
PPE is essentially intended to be used individually. If PPE is worn by more than
one
person because of special circumstances, all measures should be taken to
ensure that
such use does not cause any health or hygiene problems.
The need to use PPE in the work environment means the employer must
implement
an appropriate system for PPE selection with regard to the hazards, the
correct
use of the PPE and the level of protection it provides. The system should
include at
least the following areas:
• Risk assessment that will enable selection of the appropriate type of
equipment
and protection level (i.e. hazards identification, influence on the body,
excess of exposure limits)
• Workstation characteristics, including the occupational activity of the
worker, microclimate, space limitation, need for movement and
communication,
evacuation speed from the hazard zone, and additional hazards such
as fire or explosion
• Participation of PPE users in the process of selecting technical solutions
• Continuous training for workers, with special attention to increasing
awareness
of the effects of not using PPE, understanding the instructions for use,
practical adjustments in use, time limits, and problems that may occur
during
use
• Marking areas where PPE must be used
• Ensuring the correct method of storage, maintenance, and necessary
servicing
• Constant monitoring by audits of the PPE to ensure correct use, storage,
technical conditions, and updating training
Ensuring the correct implementation of the above-mentioned tasks requires
thorough
knowledge about the chemical and physical properties of harmful substances
and the
technical aspects of PPE, especially its protective properties dependant on the
type
of hazards as well as ergonomic requirements, including the psychophysical
load
related to the use of PPE. Chosen features of individual types of PPE are
presented
below, including information that may be useful when selecting PPE
appropriate to
the given hazard and ergonomic requirements.

26.2.1 P rotective Clothing

Protective clothing is the most commonly used type of PPE; it protects the
worker
from dangerous and harmful factors that occur in the work environment. The
type
of protective clothing depends on the type of harmful or dangerous factors
occurring
at the workstation. Therefore, clothing should be classified based on its
protective
properties. Clothing is classified as that providing protection against
mechanical,
thermal, chemical and biological agents, high visibility warning clothing, and
as
providing protection from electric shock, electromagnetic radiation, or
drowning.
The protective properties of the clothing are ensured by the use of appropriate
materials to create a barrier against dangerous factors or to sufficiently
reduce their
effects so that they are no longer a danger for the user. Depending on the
type of
harmful factors the worker is exposed to, the clothing can be made of textiles,
such
as impregnated fabrics, fabrics, nonwovens and knitwear coated on one or
both sides
with plastic, fabrics and knitwear made of high-efficiency fibres, and systems
of
materials and leather, plastic or even metal rings. When selecting clothing for
protection
against hazards, it is important to know the protective properties of the
material
and choose an appropriate class of parameters that is adequate for the level
of risk.
Clothing for protection against mechanical hazards protects the worker from
mechanical injuries caused by cuts, punctures, entanglement in the moving
parts
of devices, and the effects of impact. Clothing made of metallic materials such
as
wire mesh or appropriately jointed metal elements protects against puncture
by
hand knives, and multilayer fillers are used to protect against injuries by chain
saws.
Contact with a chain saw causes the fibres to entangle themselves with the
chain in
the driving system, block its movement and stop the saw.
High-visibility warning clothing is intended for use when the presence of the
wearer
must be visually signalled. Suits, jackets, vests, and trousers are examples of
typical
warning clothing. The clothing should be made of at least 0.5 m2 background
material
and at least 0.13 m2 retroreflective material. The chromaticity coordinates and
luminance
factors for fluorescent colours provide the protective properties of the
background
material: yellow, orange–red, and red. For retroreflective materials the
coefficient of
retroreflection, which depends on the entrance angle of light and the angle of
observation,
is the protective property.
Clothing protecting against heat and fire protect the worker—depending on its
intended use—against the effects of the following agents: flames, infrared
radiation,
sparks, liquid metals splatter, hot metal splinters, and contact with hot objects
and surfaces. The professional groups most exposed are steelworkers,
foundrymen,
welders, and firefighters. Clothing for protection against heat is obtained by
the use
of single materials; when the risk increases, multilayer materials or
combinations of
materials are used. If there is a risk of fire at a low level of infrared radiation
and an
air temperature below 50°C, materials made of aramid fibres, wool, or
chemically
modified fabrics made of flame-resistant cotton are used. In a work
environment
where the risk of a higher level of infrared radiation (up to 20 kW/m2) is
present,
clothing made of aluminised material that reflects the radiation is used. The
design of
this type of clothing is adapted to the hazard level and work conditions. At
workstations
where the intensity of infrared radiation is greater than 20 kW/m 2, the clothing
is made of multilayer material combinations, for example, the outer layer
could be
an aluminised material made of aramid yarns, glass fabrics, wool, cotton, or
nonflammable
impregnated viscose; the inner layer could be aramid fabrics, wool, or
nonflammable impregnated cotton.
Protective clothing against cold is used for those who work in open space at
temperatures
lower than standard as well as for those working in closed unheated spaces
and in cold storage areas. The thermal insulation of the clothing depends on
the
thickness of the materials used and the number of layers. Specially prepared
nonwovens
are often used for the warming layers. If the ambient temperature is very
low, the thickness of efficient insulating layers can greatly increase the mass
of the
clothing. Clothing equipped with heating systems can be used as an
alternative. At
many workstations in cold microclimates, where the amount of emitted heat
and the
need for protection against cold changes with the activity of the worker, the
desired
comfort can be achieved by the use of active clothing whose insulation
changes in
tandem with the climatic changes of the external environment and the
amount of
heat emitted by the user (Kurczewska and Les´nikowski 2008). Heating inserts
made
of steel yarn are the active elements of the clothing. Activation and
deactivation of
the voltage powering the heating inserts are achieved by a control system
that collects
and analyses data from temperature microsensors placed on the body under
and
on the clothing. Figure 26.1 shows heating inserts in active clothing.
Exposure to biological agents occurs at many workstations related to
agriculture,
sewage treatment and waste disposal and at hospitals and diagnostic and
veterinary
laboratories, where it is necessary to use appropriate protective clothing. The
barrier
material of the clothing should be resistant to penetration by infectious agents
in
fluids, liquid aerosols, and airborne particles. The design of the protective
clothing
against biological agents depends on the type of infectious agent and
resembles the
design of protective clothing against chemical agents.
The properties of clothing for protection against chemical agents should be
adapted to the aggregation of the chemical substance, its type and the
concentrations,
and the intensity of its effect on the clothing. Clothing that completely isolates
the body from the outside environment—so-called gastight clothing—belongs
to this
group, as does clothing that protects only against accidental low-volume
splashes of
chemical substances. Such clothing can be made of textiles, knitwear, or
nonwovens
coated with plastics or impregnated textiles as well as foil, depending on its
intended use. The breakthrough time, that is, the time it takes a chemical to
permeate

Figure 26.1

Figure 26.2

the protective
barrier, determines the barrier properties of the materials used. The
design of the clothing determines its intended use.
Workers at risk of long exposure to high-intensity, high-frequency
electromagnetic
fields (in the range of 300 MHz–300 GHz and with a wavelength of 0.001–0.03
m)
must use clothing that protects against microwave radiation. Such clothing is
intended
mainly for operators of equipment that emits microwave radiation and
workers who
service and maintain transmitters, radio stations, cellular network
transmitters, satellite
communication systems, radars, and so on (Andrzejewska and Kurczewska
2004). Protective shielding properties are ensured by using electroconductive
yarn
fabric. An appropriate clothing design is also important (Figure 26.2).
Clothing can also protect against drowning in case of an accidental fall into
water.
Figure 26.3 shows a safety protection suit (Bartkowiak et al. 2006) worn for
work
in harbours and industrial buildings on the waterfront or in offshore waters
(wharfs,
shipyards, docks, river dams, hydroelectric plants, and so on).
Clothing made of rubber filled with lead reduces the exposure to ionising
radiation,
that is, X-rays. It protects the front and sides of the body from the collarbone
to
the knees and is fastened at the back with buckles. The protective properties
of such
clothing are given by the attenuation equivalent, that is, the thickness of the
lead
layer that weakens X-rays of a given energy.
Protective clothing, apart from ensuring a certain level of protection against
one or
many hazards occurring simultaneously, must not have harmful effects on the
user.
Harmful substances such as carcinogens or allergens cannot be used for its
design;
the pH of the materials should be between three and nine. Protective clothing
should
also meet ergonomic requirements, that is, it must be designed in a way that
a user is
able to perform tasks without any difficulty or additional load. Anthropometric
elements
are therefore taken into account in the design of protective clothing in order
to
adjust the clothing to the body. Thermal properties (enabling the transfer of
heat and

Figure 26.3

sweat), sensorial aspects (disturbances to senses such as hearing, smell), and

biomechanical
properties (reducing musculoskeletal system load) are also considered.
The development of plastic and composites has created real possibilities for
designing clothing properties according to ergonomic principles. The materials
used
in protective clothing create a barrier against harmful agents and at the same
time
are permeable and allow the transfer of excessive heat produced by the body.
The
microclimate that is created under this type of clothing has a lower humidity
and
temperature compared to traditional barrier-coated materials. Materials that
are permeable
to water vapor are made of microfibres, laminates of flat textile products,
and permeable membranes and are used mainly to produce clothing for
protection
against biological and chemical agents. They cannot be used for some types
of protective
clothing, for example, protective clothing intended for work with aggressive
chemicals in liquid, vapour, and gaseous forms. One method used to reduce
discomfort
in this type of clothing is installing cooling systems in the clothing structure,
for
example, induced liquid circulation or induced air circulation (Muir 2001; Nag
et al.
1998). While it is generally believed that cooling systems lower the thermal
load on
the user, they have certain shortcomings, such as large mass, reduced
mobility of the
worker, and water vapour condensation.
Use of the appropriate multilayer underwear with synthetic diffusive layers
and
hygroscopic sorptive layers improves the microclimate under the clothing, and
thereby thermal comfort, when working in barrier impermeable protective
clothing
(Bartkowiak and Błaz˙ejewski 2003). Use of superabsorbent inserts under the
clothing
reduces discomfort caused by excessive sweating (Bartkowiak 2006).
Use of the new generation of clothing that support the thermoregulation
processes
of the user’s body is increasing. Such clothing is referred to as ‘active’ or
‘intelligent’.
Clothing with phase-change materials (PCM; Reinertsen et al. 2008) is an
example of such innovative products. PCM (Figure 26.4) have appeared in the
new
generation of textile fibres and are processed using traditional textile
technologies.

Figure 26.4

Research was carried out on their use in protective clothing and underwear,
and the
researchers
proved that the products developed with PCM reduce the user’s thermal
load. This new-generation protective clothing also includes garments for
rescue
services, for example, firefighters. Electronic microcircuits are implanted into
the
garment in order to monitor the user’s physiological parameters and the level
of
hazards the user is exposed to. The garments are intended to control the
firefighter’s
physiological condition based on the environmental conditions and the
workload (the
body energy expenditure and resulting load).
Body systems can be monitored with clothing elements by collecting
information
on the temporary values measured on the individual user of the garment and
transferring them by radio to the monitoring centre, based in a fire car. The
centre is
equipped with a computer system that analyses the situation unfolding in real
time
and provides information indispensable for making decisions on the necessity
and
methods of evacuating firefighters. A diagram of the firefighter’s monitoring
system
during an operation is shown in Figure 26.5.
26.2.2 H and and Arm Protection
Protective gloves provide basic hand and arm protection. Gloves ensure the
protection
of the hands, and if their cuffs are long enough they can also protect part of
the
forearm and the arm. It is particularly important that gloves have the
appropriate
protective properties but do not restrict the dexterity, accuracy, and firmness
of the
user’s grip when working and thus add to the risk of accidents at work caused
by inappropriate
or manual work that is too slow. Gloves must ensure protection of the hand
against many different harmful and dangerous substances. When seeking to
assure
protection against several hazards, combinations of different materials are
typically
used, limiting the comfort. It is essential to strike a balance between
protective
and
figure 26.5

usability properties. Because of the hazardous situations in which gloves are

used,
the time needed to put on and take off the gloves should be the shortest
possible. It
is also crucial to fit the size of the glove to the user’s hand. Gloves that are too
tight
not only cause discomfort, but also hasten the loss of protective properties,
whereas
gloves that are too large do not ensure the necessary protection and
additionally
make work difficult. Depending on the precision required, gloves with one,
three or
five fingers can be chosen.
Gloves for protection against minor and average mechanical injuries are often
made of combinations of leather and fabric, and fabrics and knitted fabrics
partly
or wholly coated with plastic or rubber or with polymer dots. Gloves can also
be
knitted using different types of yarn, for example, polyester, polyamide,
aramid,
core-spun and polyethylene. These also ensure protection against mechanical
risks
such as abrasions, cuts or punctures. Knitted gloves, because of their design,
are not
recommended for protection against punctures, unless the knitted fabric is
coated
with plastic or rubber. Double gloves are also an interesting solution—they are
made
up of an inner knitted glove with an outer material on the palm side covered
with
steel plates and an outer glove made of polymer. These gloves provide a high
level
of protection against cuts and punctures. When a worker needs protection
against

figure 26.6

serious injuries, he or she should use specialised gloves. Gloves made of chain
mail
(Figure 26.6) can serve as an example. They are used for protection against
cuts and
stabs by hand knives. These types of gloves are also recommended for hand
protection
when working with powered knives. To ensure comfort during use, inner
gloves
made of cotton yarn are often used. Gloves that protect against cuts by hand-
held
chain saws are another example of specialist gloves. They protect the hands
from the
cuts caused by the chain slipping, clogging, or braking.
Gloves protecting against thermal risks are most often made of fabrics or
knitted
yarn fabrics such as Kevlar, Nomex, Twaron, Preox, PBI, nonflammable
impregnated
cotton, and wool yarn. Aluminised fabrics and heat-resistant leathers are also
used.
Gloves ensuring protection against different forms of heat or fire (flame,
convective
heat, contact heat, radiant heat, small splashes, or large quantities of molten
metal)
are made by assembling the above-mentioned materials. To ensure thermal
insulation,
special insulating inserts are used, for example nonwovens. Cattle leather and
fabrics
are used in the design of gloves protecting against cold. These can also be
made of
plastic or rubber as well as knitwear or with polymer-coated fabrics.
Nonwovens and
knitted fabrics, for example, acrylic or woollen artificial fur or polyamide foam,
can
be used for the thermo-insulating function of the inner layer of the gloves.
Waterresistant,
permeable membranes are used in certain designs of gloves.
Tight gloves made of different types of rubber (e.g. natural rubber or synthetic
rubber—
polychloroprene, polyacrylonitrile, butyl, viton) or plastics (polyvinyl chloride,
polyvinyl alcohol, polyethylene, hypalon) protect hands from contact with
chemical substances. Gloves not wholly made of plastic, rubber, or fabrics and
knitwear
coated with polymer cannot be used for protection against chemical agents. If
all-polymer or all-rubber gloves are used, an inability to evaporate sweat may
be a
problem and cause discomfort. Moreover, allergies may result from direct or
indirect
contact of human skin with the components of the rubber mixture. Sensitivity
to the
latex in natural rubber is particularly common. Additionally, powder or other
lubricants
used to facilitate putting on and removing gloves can cause skin irritation.
To increase the comfort of all-polymer or all-rubber gloves, some of products
are
made with knitted supports or are flocked, that is, the inside is covered with a
thin
layer of cotton dust. Gloves for protection against chemical substances very
often
protect the skin against micro-organisms as well. Gloves resistant to
penetration,
that is, the movement of chemical substances through porous materials,
seams, pinholes
or other imperfections in the material of the glove on nonmolecular level, are
an efficient barrier to bacteria and fungi. However, they do not provide
protection
against viruses.

At many workstations, multifunctional gloves that ensure simultaneous

protection
against many agents are required. Gloves that offer simultaneous protection
against thermal and mechanical risks are currently available. Gloves for
protection against chemical, mechanical, and thermal risks (contact with hot
objects) that are also suitable for contact with food are also produced. One
innovative
solution is gloves that protect against mechanical risks (cuts, punctures,
abrasions), select chemical agents, micro-organisms, and radioactive
contamination.
This type of glove is made of many layers of different polymers on a knitted
support.
Laboratory tests carried out based on the standards harmonised with directive
89/686/EEC confirm the protective properties of gloves. Gloves are most often
rated
by level of performance (e.g. 1, 2), which is indicated next to the appropriate
pictograms
on the glove (Figure 26.7).

figure 26.7

figure 26.8

Apart from the appropriate selection of gloves to fit the hazards and fulfil
ergonomic
requirements, users should be able to determine the end of the service life of
the glove. Usability, storage, and maintenance conditions influence the
protective
properties of the gloves. Changes in the material of the gloves observed
during use
should signal a need for withdrawal from use. This is especially important
where
protection against chemical risks is required, because the actual level of
protection
in this category of gloves depends on ambient temperature and humidity,
contact
with other chemical substances, mechanical wear of the gloves, and the
microclimate
conditions under the glove. Among the directions for prolonging hand
protection is
the development of end-of-service-life indicators. These indicators enable the
user to
decide when the protective properties cease to be effective and discard the
gloves. An
example of such a solution is presented in Figure 26.8.
26.2.3 F oot Protection
At many workstations, for example, construction sites, metallurgical and
machinery
industries, and mining, workers are exposed to risks of injury to the lower
limbs,
especially the feet. The risks are directly related to the work performed as well
as to the harmful effects of the floor’s surface or the environment. Footwear
selected
according to the risks provides foot protection. Footwear, depending on the
design
and materials used, as well as additional protective components, offer
protection
against various mechanical damages, such as punctures of the sole of the
foot, injury
or crushing of the toes or metatarsus, thermal injuries caused by excessively
high or
low temperatures, electric shock, and so on.
According to the European standards (PN-EN ISO 20345 2007; PN-EN ISO
20346:2007; PN-EN ISO 20347:2007), the following categories of footwear are
ranked as PPE for the lower limbs:
• Safety shoes: Equipped with toecaps to protect toes against impact up to
200 joules (J) and compression up to 15 kilonewtons (kN; safety toecaps).
• Protective footwear: Equipped with toecaps to protect toes against impact
up to 100 J and compression up to10 kN (protective toecaps).
• Occupational shoes: Has protective properties but without toe protection.
As for the materials used, classification I footwear includes footwear made
from
leather and other materials (excluding all-rubber and all-polymeric footwear),
and
classification II includes all-rubber entirely vulcanised and all-polymeric
entirely
moulded footwear.
Depending on the length and design of the upper and particular models of
safety,
protective and occupational footwear are classified as one of the following
models:
A model—low upper shoes (• half boots, sandals, clogs)
• B model—ankle boots
• C model—half-knee boots
• D model—knee-high boots
• E model—thigh-high boots
An open heel is only acceptable in model A of classification I.
Additional protective elements of footwear include:
• Safety and protective toecaps protecting the toes
• Penetration-resistant inserts fixed on the bottom of the shoes protecting the
foot against punctures
• Metatarsal protection fixed on the inside or outside of safety or protective
footwear
• Ankle protection to absorb impact
• Flaps protecting the metatarsus, preventing sand, stones, sparks, and
splashes
of melted metal from entering the shoe
For specialist work in some occupations, footwear should fulfil defined
requirements—
besides general requirements for safety, protective or occupational footwear—
arising from the specific character of the work environment conditions, for
example, footwear for firefighters, for professional motorcyclists, and footwear
protecting
against hand-held chain saw cuts and chemicals. Protecting against many
different dangerous and harmful agents in the work
environment,
especially when occurring simultaneously, often requires the use
of footwear that imposes a significant load on the wearer (Makinen et al.
2000).
Fulfilling the requirements of the protective properties of footwear influences
the
deterioration of its biomechanical, physiological, and hygienic properties, for
example,
the use of steel toes for protection and steel inserts to protect the foot against
punctures makes the footwear heavier and more rigid. Therefore, the
selection of
appropriate footwear should take into consideration the requirements and
expectations
of the user and should not cause significant discomfort.
A key requirement of footwear is its proper adjustment to the shape and size
of
the foot. The shoes must stabilise the foot, without compressing the dorsum
and toes
or limiting movement. The seat region should be stiffened. Even small
imperfections
in the adjustment of the footwear can cause considerable difficulties for the
user and
increase sensitivity to other factors causing discomfort, such as overheating or
excessive
humidity. The pressure of the shoe on the foot impedes the dynamic functions
and blood flow, which can have health consequences. Uppers made of more
flexible
material, which stretch more easily, are more advantageous, but cannot
stretch
too much, as the footwear should not be loose. An important feature of the
upper
part of the footwear is its ability to maintain its shape. The durability of the
shape
determines the aesthetics and comfort of the footwear. Natural leather has
elastoplastic
properties; therefore, some of the deformations occurring from stretching are
permanent. The temperature and humidity of the material influence the
degree of
deformation. The adjustment of the shape of the upper to the shape of the
foot differs
for natural leather, synthetic leather, and other synthetic materials.
The combination of materials used to form the sole of the footwear in the seat
region and its appropriate design are important for reducing limb and spine
injuries.
Microcell materials of the insole and sole can be used to absorb energy in the
heel.
The midsole absorbs the forces generated when the foot strikes the ground
and prevents
injury to the ankles, knees, hips, and lower part of the spine.
The physiological and hygienic properties of the footwear can deteriorate if full
protection is desired, in particular against extreme hazards, for example, in
metallurgy,
during firefighting, or in chemical rescue operations. The footwear used
does not assist in the transfer of heat and sweat produced in great quantities
during
physical effort, so the high temperature and excessive heat in the footwear
cause
discomfort. If such an unfavourable microclimate is prolonged, the
decomposition
of organic substances of the sweat occurs, leading to changes in the skin’s
reaction
to alkalinity and the growth of bacteria and fungi. At the same time, the
corneum
swells because of the high humidity and becomes more susceptible to
abrasions and
other mechanical injuries as well as more vulnerable to micro-organisms.
Therefore,
the materials used in footwear design must not only fulfil protective
parameters, but
also physiology and hygiene requirements, so that they can actively support
the thermoregulatory
processes of the body. An inappropriate microclimate inside the shoes
disturbs the thermoregulatory process of the feet, which in turn disturbs
activities
in the whole body. Therefore, appropriate regulation is necessary. Modern
materials
with a significant capacity and sorption dynamism, such as superabsorbents,
may be
good for use in the inner materials of the footwear (the lining and padding).

figure 26.9

To counteract the growth of micro-organisms, materials should be disinfected

even at the production stage. The materials currently available contain
bactericides
and fungicides impregnated in the molecular structure of the fibre and even in
completely
integrated assemblies of materials, combining superior thermal insulation
with the capacity to transfer humidity. They also provide active and durable
protection
against micro-organisms (Climate control for feet, 2000). Protection against
micro-organisms is a property of the fibre itself, which means that the use of
the
product does not influence its durability (unlike with the impregnation or
surface
application of bactericides and fungicides).
Ensuring protection against slipping is a vital factor in the selection of
footwear.
The majority of the materials used for the production of soles possess good
traction
on dry and rough surfaces and do not show any tendency to slip. In practice,
however,
direct friction, the so-called dry friction between two surfaces, is rarely
encountered.
The surface is usually covered with water, dust, mud, and so on. Smooth
surfaces
covered with water, oil, grease, or ice are the most dangerous. Suitably
selected materials
and the design of sole patterns increase the friction coefficient (Figure 26.9).
The cleated pattern, open to the sides, enables the diffusion of liquids. The
surface of
the cleats should be smooth, without roughness, to which the liquid clings.
The cleat
must be high enough and resistant to wear during the life of the footwear.
26.2.4 H ead Protection
In many workstations in industry, for example, mining, power, construction,
and
forestry,
the risk of head injury for workers is constantly present. The most serious
are mechanical injuries, which can be the result of the impact of falling objects
or collision with fixed objects at the workstation. Because of the nature of
these
work activities, it is not always possible to eliminate such risks with
appropriate
organisational
solutions or collective protective equipment. Therefore, the only way to ensure
the safety of workers is by using safety helmets. The type of helmet depends
on the specific nature of mechanical risk.
If the risk is of impact by hard, fixed objects, which can cause superficial head
injuries, industrial bump caps can be used, fulfilling the requirements of the
standard
PN-EN 812 (2002; Figure 26.10).
Workers exposed to a risk of falling objects, which can cause serious injuries
to
the skull, brain or cervical vertebrae, require industrial safety helmets fulfilling
the
requirements of standard PN-EN 397 (1997). Examples of designs of this type
of helmets
are presented in Figure 26.11. Workers exposed to a risk of impact to the
head by
extremely heavy falling objects from heights and with sharp edges as well as
blows to
the top of the head by dangerous objects at the workstation (Baszczy n´ski
2002) should
be equipped with a helmet fulfilling the requirements of standard PN-EN
14052.
2006(U), Examples of designs of this type of helmets are presented in Figure
26.12.

figure 26.12

Safety helmets, depending on the type, can also protect the head of wearer
against dangerous factors such as electric shock, transverse compressive
forces,
splashes of liquid metal, and high temperatures. Such abilities are given on
the
helmet as well as in the instructions for use provided by the manufacturer.
Helmets
can also be a structure for mounting other PPE, for example, eye and face
protectors,
respiratory protective equipment, nape protection, and supporting equipment
such as cap lamps.
The helmet must be carefully selected to ensure the safety of worker’s head.
Some
aspects that must be considered are the risks that arise at the workstation
(e.g. falling
objects with sharp edges, splashes of liquid metal), the atmospheric
conditions in
which the helmet will be used (temperature, in particular), the ability to adjust
it to
fit the head of the individual wearer, and properties indispensable for a helmet
used
at a given workstation (e.g. enables mounting of hearing protectors).
Helmets lose their protective features during use for many reasons. The most
important reasons are solar radiation, especially of the ultraviolet (UV)
spectrum,
mechanical damages, relaxation of internal stress in plastics, and degradation
of
materials because of aggressive substances in the work environment. A safety
helmet
can be used only for the duration indicated by the manufacturer, unless other
disqualifying damages occur. A safety helmet that has been hit with great
force must
be discarded, even if an inspection does not reveal any damage.
26.2.5 E ye and Face Protection
Natural protective mechanisms protect the eye against external factors. For
example,
a thin layer of slightly oily lachrymal fluid produced by the conjunctiva
protects
it against less intensive pollution. Eyelids and lashes ensure the protection of
the
eye against fine foreign bodies. However, this natural protection of the eye
against
external factors is often insufficient in workplaces as well as in everyday life.
In such
situations, extra eye protection is required. It should be used in places where
the following
hazards may occur:
Impact ( • e.g. fragments of solids)
• Optical radiation (e.g. radiation related to welding, sun glare, laser
radiation)
• Dusts and gases (e.g. coal dust or aerosols of harmful chemical substances)
• Droplets and splashes of fluids (e.g. splatter occurring when pouring
fluids)
• Molten metals and hot solid bodies (e.g. sparks of molten metal during
metallurgical
processes)
• Electric arc (e.g. occurring while working on high-tension equipment)
The eye can be protected against the aforementioned hazards using eye
protection
equipment falling in the following four basic categories:
1. Spectacles
2. Protective goggles

3. Face shields
4. Welder’s face shields (includes hand screens, face screens, goggles, and
hoods)
To ensure eye protection and vision, the PPE of the aforementioned categories
is
equipped with vision systems, oculars, meshes, or filters. Filters include
welding
filters, UV filters, infrared filters, sun glare filters, and filters protecting against
laser
radiation. Eye protection equipment may be part of respiratory protective
devices
(full masks that have vision systems) or head protection equipment (face
shields
mounted in industrial protective helmets). Eye protection equipment of all
categories
is composed of a transparent part (vision systems, oculars, meshes, or filters)
and a
frame (spectacles and goggles) or housing with a harness (shields).
Spectacles are the most widely used eye protection equipment. They should
provide
forehead protection against dangerous splatters of fluids or fragments of solid
bodies.
A model of such spectacles is presented in Figure 26.13. If the worker requires
a
higher degree of eye protection, he or she can use protective goggles. Their
construction
ensures tight adhesion to the user’s face, which enables them to protect
against
biological factors. The ventilation systems of goggles often differ greatly from
one
from another and are also very important. Figure 26.14 presents goggles with
direct
and indirect ventilation systems. Goggles with indirect ventilation systems
ensure
better protection against droplets and splashes of harmful substances. The
majority
of goggle constructions allow their use with corrective glasses; however,
before
choosing and purchasing the equipment verification of the quality is
recommended.
If the hazards require protection of the entire face, face shields should be
used.

figure 26.14

Face shields protect the entire face; their large protective surface minimises
the
probability of penetration of dangerous fluid splatter. Face shields may be
used with
spectacles, corrective glasses, goggles, and some respiratory protection
devices.
The last of the basic categories of protective eye equipment are welder’s face
shields, that is, devices protecting the user against harmful optical radiation
and
other specific hazards arising during welding and/or related techniques.
Welder’s
face shields include face screens, hand screens, goggles, spectacles, and
hoods.
The intended use of eye protection equipment and its construction determine
its protective properties. If eye protection equipment is intended to protect
against
impacts of solid bodies, fluid splatters, and drops of molten metal, it must
have
mechanical resistance (in low and high temperatures) and tightness and
resistance
to ignition in contact with items of a much higher temperature (up to about
1500°C).
To determine if eye PPE protects against the consequences of electric arc
flash, the
electrical insulation properties of its materials should be verified. Examining
spectral
characteristics of optical radiation transmittance through transparent
elements
(spectacles, vision systems, filters) allows determination of the part of the
radiation
spectrum against which the equipment ensures protection. The requirements
for eye
and face protective equipment are divided into two categories: (1) nonoptical,
all the
elements of construction, and (2) optical, only the ocular area.
Examination methods for verifying the fulfilment of requirements are included
in the standards PN-EN 167 (2005) and PN-EN 168 (2005). A symbol is
assigned to
each given purpose of eye protection equipment (digits: 3, 4, 5, 8, or 9); this
symbol
should appear as part of the equipment markings. The purposes of eye
protection
systems, the relevant symbols and a short description of the fields of use are
presented
in Table 26.1.
A common element in the majority of eye protective equipment is ocular.
Because
its basic function is protection against impact, it is often called the antisplinter
ocular,
and it is mounted in protective equipment such as antisplinter spectacles,
goggles or
face shields. If the ocular has filtration properties (e.g. lowers the intensity of
UV
radiation), it can also act as a filter. Most often, the ocular is made of a
polycarbonate

tabel 26.1