Module 3

• Safety in Construction industry- control measures to reduce the risk

• Scaffolding and Working platform
• Welding and Cutting
• Excavation Work
• Concreting
• Electrical Hazards, Protection against voltage fluctuations, Effects of shock
on human body.
• Radiation Hazards, Types and effects of radiation on human
body, disposal of radioactive waste.
Scaffolding
 Scaffolding
• A scaffold is an elevated, temporary work platform.
There are two basic types of scaffolds:
• Supported scaffolds
• Suspended scaffolds
And then there are
• Other types of equipment.
• Supported scaffolds, which consist of one or more
platforms supported by rigid, load- bearing
members, such as poles, legs, frames, outriggers,
etc.
• Suspended scaffolds, which are one or more
platforms suspended by ropes or other non-rigid,
overhead support.
• Other types of equipment, principally scissor lifts
and aerial lifts, can be regarded as other types of
supported scaffolds.
Supported scaffolds
Suspended scaffolds
Scissor lifts and Aerial lifts
• Workers who use scaffolds can be divided into
three groups:
1. Designers
2. Erectors/Dismantlers
3. Users

1. Designers
• Scaffold designers are workers who are qualified to
design scaffolds.
 2. Erectors/Dismantlers
• Erectors and dismantlers are workers whose principal
activity involves assembling and disassembling
scaffolding before other work can begin, and after that
work, or a portion of it, has been completed.
• A qualified person must do adequate preplanning to
assure the safe erection and use of the scaffold.
Preplanning includes:
• Determining the type of scaffold necessary for the job.
• Determining the maximum load for the scaffold.
• Assuring a good foundation.
• Avoiding electrical hazards.
 3. Users
• Scaffold users are workers whose work requires
them to be supported by scaffolding to access the
area of a structure where that work is performed.
• Employers are required to have a qualified person
provide training to each employee who performs
work while on a scaffold.
• The training must enable employees to recognize
the hazards associated with the type of scaffold
being used and to understand the procedures to
control or minimize those hazards.
 General requirements of Scaffolds
1. Capacity requirements
2. Scaffold Platform requirements
3. Guardrails requirements
4. Footing and foundation requirements
5. Access Requirements
6. Fall Protection Requirements
7. Falling object protection
 1. Capacity requirements
• Each scaffold and scaffold component must
support, without failure, its own weight and at least
4 times the maximum intended load applied or
transmitted to it.
• A qualified person must design the scaffolds, which
are loaded in accordance with that design.
 2. Scaffold Platform requirements
• Each platform must be planked and decked as fully as possible
with the space between the platform and uprights not more
than 1 inch (2.5 cm) wide.
• The space between the platform and the uprights must not
exceed 9½ inches (24.1 cm)
• Each scaffold platform and walkway must be at least 18
inches (46 cm) wide, guardrails and/or personal fall arrest
systems must be used.
• It is prohibited to work on platforms, cluttered with debris.
 3. Guardrails requirements
• To ensure adequate protection, install guardrails
along all open sides and ends before releasing the
scaffold for use by employees.
• Guard rails include a top rail mid rail and toe board,
which are supported at interval not more than 8
feet.
• Steel or plastic banding must not be used as a top
rail or a mid rail.
Top rail

Mid rail

Guardrails
4. Footing and foundation requirements
• Supported scaffolds' poles, legs, posts, frames, and
uprights must bear on base plates and mud sills, or
other adequate firm foundation.
 5. Access Requirements
• Employers must provide access when the scaffold
platforms are more than 2 feet (0.6 m) above or below a
point of access.
• Direct access is acceptable when the scaffold is not more
than 14 inches (36 cm) horizontally and not more than 24
inches (61 cm) vertically from the other surfaces.
• Employees erecting and dismantling supported
scaffolding must have a safe means of access provided
when a competent person has determined the feasibility
and analyzed the site conditions.
• Several types of access are permitted:
• Ladders, such as portable, hook-on, attachable, and
stairway
• Stair towers
• Ramps and walkways
• Integral prefabricated frames
 6. Fall Protection Requirements
• Employers must provide fall protection for each
employee on a scaffold more than 10 feet (3.1 m)
above a lower level.
• A competent person must determine the feasibility
and safety of providing fall protection for
employees erecting or dismantling supported
scaffolds.
• Fall protection includes Guardrail Systems and
Personal Fall Arrest Systems.
 Personal Fall Arrest System (PFAS)
• A personal fall-arrest system is a system used to
arrest an employee, in a fall from a working level.
• Personal fall-arrest systems include a Body wear,
Connecting device, Anchorage connector and
Anchorage.
 Falling Object Protection
• To protect employees from falling hand tools,
debris, and other small objects,
• Install
• Toe boards
• Screens
• Guardrail systems
• Debris nets
• Catch platforms
• Canopy structures, or barricades
• In addition, employees must wear hard hats.
 Requirements for all types of
suspension scaffolds
• Employers must ensure that all employees are trained to
recognize the hazards associated with the type of scaffold being
used.
• All support devices must rest on surfaces capable of supporting at
least four times the load imposed on them by the scaffold.
• A competent person must evaluate all direct connections prior to
use to confirm that the supporting surfaces are able to support the
imposed load.
• All suspension scaffolds must be tied or otherwise secured to
prevent them from swaying, as determined by a competent
person.
• Guardrails, a personal fall-arrest system, or both must protect each
employee, more than 10 feet (3.1 m) above a lower level, from falling.
• A competent person must inspect ropes for defects prior to each
workshift and after every occurrence that could affect a rope's
integrity.
• When scaffold platforms are more than 24 inches (61 cm) above or
below a point of access, ladders, ramps, walkways, or similar surfaces
must be used.
• When using direct access, the surface must not be more than 24
inches (61 cm) above or 14 inches (36 cm) horizontally from the
surface.
• Emergency escape and rescue devices must not be used as working
platforms, unless designed to function as suspension scaffolds and
emergency systems.
 Hazards In Scaffolding
Employees working on scaffolds are exposed to
these hazards:
• Fall from elevation
• Struck by falling tools /debris
• Electrocution
• Scaffold collapse
• Planking failure
 Solutions
1. Scaffold must be sound, rigid and sufficient to carry its own
weight plus four times the maximum intended load without
settling or displacement. It must be erected on solid footing.
2. Unstable objects, such as barrels, boxes, loose bricks or
concrete blocks must not be used to support scaffolds or
planks.
3. Scaffold must not be erected, moved, dismantled or altered
except under the supervision of a competent person.
4. Scaffold must be equipped with guardrails and toeboards.
 Solutions
5. Scaffold accessories such as braces, trusses, ladders etc., that are
damaged or weakened from any cause must be immediately
repaired or replaced.
6. Scaffold platforms must be tightly planked with scaffold plank
grade material or equivalent.
7. A “competent person” must inspect the scaffolding and, at
designated intervals, reinspect it.
8. Rigging on suspension scaffolds must be inspected by a
competent person before each shift and after any occurrence
that could affect structural integrity to ensure that all
connections are tight and that no damage to the rigging has
occurred since its last use.
 Solutions
9. Synthetic and natural rope used in suspension
scaffolding must be protected from heat-producing
sources.
10.Employees must be instructed about the hazards of
using diagonal braces as fall protection.
11.Scaffold can be accessed by using ladders and stairwells.
12.Scaffolds must be at least 10 feet from electric power
lines at all times.
Welding and Cutting
 Welding and Cutting
• Welding, cutting and allied operations take place in
a wide variety of locations under many different
conditions.
• These operations are carried out in factories,
building construction sites, pits, mines, tanks, ship
compartments and literally everywhere that metals
are joined or cut.
 Welding
• Welding is a joining process in which metals are heated,
melted and mixed to produce a joint with properties
similar to those of the materials being joined.
• Generally an electric arc, a flame, pressure, or friction is
used as a heat source.
• The most common heat source is an electric arc.
 Hazards in welding and cutting
operations
1. Fire and Explosion Hazards
2. Electric Shock
3. Noise hazards
4. Exposure to UV and IR Radiation
5. Burns
6. Exposure to fumes and gases
 1. Fires and Explosion Hazards
• Fires and explosions are two of the main hazards associated
with welding and other hot work activities, where these are
not effectively managed, severe consequences can occur,
including serious or fatal injuries and destruction of property.
• Welding, cutting and allied processes produce molten metal,
sparks, slag and hot work surfaces.
• These can cause fire or explosions if precautionary measures
are not followed.
• During the operations, sparks and spatter fly-off. Flying
sparks are the main cause of fires and explosions in welding
and cutting.
 Precautions
• All combustible materials should be removed or
adequately protected.
• If a fire risk is present, a responsible person should keep
the welding site under observation for at least an hour
after the completion of the work.
• Suitable fire extinguishing apparatus should be always
kept at hand.
 2. Electric Shock
• During the arc welding process, live electrical
circuits are used to create a pool of molten metal.
• Therefore, when welding, the workers are at risk of
experiencing an electric shock.
• Electric shock is the most serious hazard posed by
welding and can result in serious injuries and
fatalities, either through a direct shock or from a
fall from height after a shock.
 Precautions
• Wear protective clothing including insulating safety boots
• Stand or kneel on a mat of insulating material which should be
kept dry
• Only use an all-insulated electrode holder
• Place the welding power source outside the working environment
• Ensure qualified support staff are in close proximity outside the
working space to give first aid and switch off the electrical supply
• When welding outside, check the power source protection rating is
adequate for the environment
• Do not weld in the rain without a suitable cover
 3. Noise Hazards
• When carrying out welding activities, you are likely to be exposed
to loud, prolonged noises. A loud noise is considered to be above
85 dB, and welding activities such as flame cutting and air arc
gouging can produce noise levels of over 100 dB. This can be very
damaging to the ears and can result in hearing impairment.
• Regular or immediate exposure to loud noises can cause
permanent noise-induced hearing loss.
• Noise-induced hearing loss can have the following side effects:
• Ringing in the ears, known as tinnitus.
• Occasional dizziness, known as vertigo.
• Increased heart rate.
• Increased blood pressure.
 Precautions
• Hearing protection protects the worker from noise hazards.
• It’s important to wear ear protection that is appropriate for the
noise created in the workplace, and it should be fire resistant, if
there is a risk of sparks or splatter entering the ear.
 4. Exposure to UV and IR Radiation
• Looking at the intense bloom of UV light produced when welding,
without appropriate PPE or welding curtains, can result in a
painful and sometimes long-lasting condition called Arc-eye.
• Many factors can affect the severity of this condition, such as
distance, duration and the angle of penetration.
• Long-term exposure to arc flashes could also potentially result in
cataracts and lead to a loss of vision.
• Other forms of eye damage include:
• Foreign bodies entering the eye, including grit, sparks and dust.
• Particulate fumes and gases, which could lead to conjunctivitis.
 Precautions
Welding helmets with side-shields:
• Welding helmets protect the worker not
only from UV radiation, but from particles,
debris, hot slag and chemical burns.
• It’s important that the worker should wear
the right lens shade for the work and
follow the manufacturer’s guidelines.
• Always wear the helmet when welding or
in the vicinity of another welder.
• The intensity of the radiation produced, decreases away from the
welding arc, but those who are within 10 metres away from the arc are
still susceptible to arc-eye. Therefore, it’s important that a workers
should remain behind welding curtains or wear the correct PPE, even if
they are not carrying out the welding operation.
 5. Burns
• The combination of high-temperature welding arcs, UV
rays and molten metal means workers are susceptible to
severe burns when welding.
• These burns can affect the skin or eyes and can be very
serious.
• Burns usually occur when welders think they can skip
taking precautions for a few quick welds.
 Precautions
• Fire resistant clothing
• Fire resistant clothing protects the worker from heat, fire and
radiation created in the welding process and shields from burns.
• It should have no cuffs, and pockets must be covered by flaps or
taped closed.
• Boots and gloves
• Insulated, flame resistant gloves and rubber-soled, steel toe-
capped safety shoes shield the worker from electric shocks, heat,
fire, burns and falling objects.
 Exposure to fumes and gases
• All welding and cutting operations result in the production of
a certain amount of smoke and atmosphere contamination.
• All welding processes produce fumes, but the composition
and concentration of the fumes can vary widely.
• The largest component of all welding fumes is iron oxide.
• Depending on the welding process and the material being
welded, the fumes may also contain various combinations of
the metals such as aluminium; cadmium; chromium; copper;
fluorides; lead; manganese; molybdenum; nickel; tin;
titanium; vanadium; and zinc and other chemical compounds.
 Exposure to fumes and gases
• Copper, aluminium, and other metals are occasionally alloyed
with beryllium, which is a highly toxic metal. When a metal like
this is welded or cut, high concentration of toxic beryllium may
result in, shortness of breath, chronic cough, weight loss, fatigue
and general weakness.
• The gases generated during welding include ozone, nitrogen
oxides, carbon monoxide, and carbon dioxide.
• Carbon dioxide and carbon monoxide generated may be a
health hazard, only if welding is carried out in enclosed or
confined spaces with inadequate ventilation.
 Precautions
• Adequate ventilation should be provided.
• Respiratory protective equipment (RPE): Where engineering
controls alone are not sufficient to suitably control exposure to
welding fumes, RPE must be provided. Anyone welding outdoors
must wear RPE when welding. The respirator must be suitable
for the work being undertaken, and must be thoroughly examined
by a trained individual at suitable intervals.
Excavation works
 Excavation and Trench
• An excavation is any man-made cut, cavity, trench, or
depression in the Earth’s surface formed by earth
removal.
• A trench is defined as a narrow excavation (in relation to
its length) made below the surface of the ground.
 Excavation hazards
Working in trenches and excavations is hazardous to both
the workers who work inside them, and to workers on the
surface. The hazards include:
1. Cave-ins or collapses that can trap or crush workers.
2. Equipment or excavated soil falling on workers (e.g.,
equipment is operated or soil and debris is stored too
close to the excavation).
3. Falling into the trench or excavation.
4. Flooding or water accumulation.
5. Exposure to a hazardous atmosphere (e.g., gas, vapour,
dust, biological contaminants, or lack of oxygen).
6. Contact with buried service lines such as electrical,
natural gas, sewage etc.
7. Contact with overhead electrical lines.
8. Slips, trips and falls as workers climb on and off
equipment, or from inappropriate access and egress
methods.
9. Being struck by moving machinery, or by falling or flying
objects.
10.Hazards related to materials handling (e.g., lifting,
struck by, crushed between, etc.).
 Factors determining the selection of
appropriate protective system to use
• Soil type
• Depth of cut
• Water content of soil
• Changes due to weather or climate
• Surcharge loads (e.g., spoil, other materials to be used in
the trench) and
• Other operations in the area
 Different types of protective systems
used to protect against cave-ins
There are two basic methods of protecting workers against
cave-ins:
1. Sloping
2. Temporary protective structures (e.g., shoring, trench
boxes, pre-fabricated systems, hydraulic systems,
engineering systems, etc.)
 Sloping
• Sloping involves cutting
back the trench wall at an
angle that is inclined away
from the work area of the
excavation.
• The angle of slope required
depends on the soil
conditions.
• Benching is a similar
method to sloping.
 Temporary protective structures
• A temporary protective structure is “a structure or device
in an excavation, trench, tunnel or excavated shaft that is
designed to provide protection from cave-ins, collapse,
sliding or rolling materials.”
• Shoring is a system that supports the sides or walls.
Shoring requires installing aluminum, steel, or wood
panels that are supported by screws or hydraulic jacks.
Wherever possible, install the shoring equipment as the
excavation proceeds. If there is any delay between digging
and shoring, no one should enter the unprotected trench.
Shoring
• Trench Boxes/ Trench shields
are commonly used in open areas
that are away from utilities,
roadways, and foundations.
Trench boxes can be used to
protect workers in cases of cave-
ins, but not to shore up or support
trench walls. They can support
trench walls if the space between
the box and the trench wall is
backfilled with soil and
compacted properly.
 Precautions to follow during an
excavation
• Do not enter an unprotected trench deeper than 1.2 metres (4 feet).
• Do not start digging before locating and de-energizing the buried
services.
• Do not enter a trench before testing the air for hazardous gasses and
vapours, or the lack of oxygen.
• Do not place the sections of pipes, piles of spoil, unused tools, and
timber, and other materials within 1 metre from the trench's edge.
• Have a means of exit provided from the inside of the trench, usually
no more than 8m (25 ft) away from any worker in the trench.
• Do not rely on natural freezing to act as a method of soil
stabilization.
• Do not work under suspended or raised loads and
materials.
• Do not stand behind a backing vehicle.
• Plan for adverse weather conditions (e.g. hot or cold
environments, storms, etc.).
• Prepare an emergency plan and rescue procedures.
• Keep first aid equipment at the site.
• Educate and train workers about all existing and potential
hazards and risks and appropriate safety measures.
Concreting
 Concreting
Potential hazards for workers in concrete manufacturing:
1. Eye, skin and respiratory tract irritation from exposure to cement dust.
2. Inadequate safety guards on equipment
3. Inadequate lockout/tagout systems on machinery
4. Overexertion and awkward postures
5. Slips, trips and falls; and
6. Chemical burns from wet concrete
 Cement Dust
Hazard: Solutions:
• Exposure to cement dust can irritate •Rinse eyes with water if they come
eyes, nose, throat and the upper into contact with cement dust and
respiratory system. consult a physician.
•Use soap and water to wash off
• Skin contact may result in moderate
dust to avoid skin damage.
irritation to thickening/cracking of
skin to severe skin damage from •Wear a P-, N- or R-95 respirator to
chemical burns. minimize inhalation of cement dust.
•Eat and drink only in dust-free
• Silica exposure can lead to lung areas to avoid ingesting cement
injuries including silicosis and lung dust.
cancer.
 Wet Concrete
Hazard: Solutions:
• Exposure to wet concrete can • Wear gloves, coveralls with long sleeves
and full-length pants, waterproof boots
result in skin irritation or
and eye protection.
even first-, second- or third-
• Wash contaminated skin areas with cold,
degree chemical burns.
running water as soon as possible.
• Rinse eyes splashed with wet concrete
with water for at least 15 minutes and then
go to the hospital for further treatment.
 Machine Guarding
Hazard: Solutions:
• Ensure that guards are in place to protect
• Unguarded machinery workers using mixers, block makers and
used in the metalworking machinery such as rebar benders,
cutters etc.
manufacturing • Establish and follow effective lockout/tagout
process can lead to procedures when servicing equipment.
• Be sure appropriate guards are in place on
worker injuries. power tools before using them.
 Falling Objects
Hazard: Solutions:
• Workers may be hit • Avoid working beneath
by falling objects conveyor belts,
from conveyor belt stacker/destacker machinery
systems, elevators etc.
or concrete block • Stack and store materials
stacking equipment. properly to limit the risk of
falling objects.
 Poor Ergonomics
Hazard: Solutions:
• Improper lifting, • Use handtrucks or forklifts when possible.
•Lift properly and get a coworker to help if a
awkward postures and
product is too heavy.
repetitive motions can •Avoid twisting while carrying a load. Shift
lead to sprains, strains your feet and take small steps in the
direction you want to turn.
and other •Keep floors clear to avoid slipping and
musculoskeletal tripping hazards.
• Avoid working in awkward postures.
disorders.
Hand truck Forklift
 Confined Spaces
Hazard: Solutions:
•Mixers and • Follow established procedures for
ready-mix trucks confined space entry and work to assure
have confined safety.
spaces that pose • Guard against heat stress when cleaning
safety risks for truck mixer drums.
workers. • Wear appropriate protective equipment
to avoid silica exposure when removing
concrete residues from inside truck
mixer drums
 Vehicles
Hazard: Solutions:
• Poorlymaintained • Make sure back-up alarms on all vehicles are
functioning.
or improperly
• Avoid overloading cranes and hoists.
handled vehicles • Use care with the load out chute on concrete mixers
can lead to to avoid injuries to hands and fingers. Beware of hot
crushing injuries surfaces on equipment and truck components.
• Guard eyes against splashes of aggregate materials
at the plant site or during loading and unloading.
other injuries for • Use hearing protection if needed to guard against
truck drivers. excessive noise exposure.
 Other Hazards
• Welding operations can lead to flash burns.
• Makeshift ladders, platforms and stairs with improper or no
guardrails make falls more likely.
• Workers can also be injured by falling concrete forms if the forms
are improperly anchored.
Electrical hazards
 How Shock Occurs
• We know that electricity travels in closed circuits through a
conductor. Electric shock occurs when the body becomes
part of the electrical circuit. This can happen when any of
the following occurs.
1. The body comes into contact with wires in an energized
circuit.
2. The body comes into contact with one wire of an
energized circuit and a path to the ground.
3. The body comes into contact with a metallic part that has
become “hot”(means a voltage is present that can cause
a Current) by contact with an energized conductor.
 Severity of Shock
The severity of the shock depends on three factors.
1. The path of the current through the body.
2. The amount of current flowing through the body.
3. The length of time the body is in the circuit.
 Types of Electrical Injury
There are four types of injury relating to electrical incidents.
• Electric Shock: Electric shock is a reflex response possibly involving trauma
which occurs when electrical current passes over or through a worker’s
body. It usually involves burns and abnormal heart rhythm and
unconsciousness.
• Electrocution: Electrocution occurs when electrical current passes over or
through a worker’s body resulting in a fatality.
• Falls: Electric shock may cause muscles to contract causing a worker to lose
his or her balance and fall. An explosion from an electrical incident can also
cause a fall.
• Burns: Electrical burns are the most common shock-related, nonfatal injury.
They occur when a worker contacts energized electrical wiring or
equipment. Although electrical burns can occur anywhere on the body, they
most often occur on the hands and feet.
 Electrical hazards
• Many workers are unaware of the potential electrical hazards
present in their work environment, which makes them more
vulnerable to the danger of electrocution. The following hazards
are the most frequent causes of electrical injuries
1. Contact with power lines,
2. Lack of ground-fault protection,
3. Path to ground missing or discontinuous,
4. Equipment not used in manner prescribed, and
5. Improper use of extension and flexible cords.
 1. Contact with power lines
• Overhead and buried power lines at your site are especially
hazardous because they carry extremely high voltage. Fatal
electrocution is the main risk, but burns and falls from elevations
are also hazards. Using tools and equipment that can contact
power lines increases the risk.
 Solution
• Look for overhead power lines and buried power line indicators. Post
warning signs.
• Contact utilities for buried power line locations.
• Stay at least 10 feet away from overhead power lines.
• Unless you know otherwise, assume that overhead lines are energized.
• De-energize and ground lines when working near them. Other
protective measures include guarding or insulating the lines.
• Use non-conductive wood or fiberglass ladders when working near
power lines.
 2. Lack of ground-fault protection
• Due to the dynamic, rugged nature of construction work, normal
use of electrical equipment at your site causes wear and tear that
results in insulation breaks, short-circuits, and exposed wires. If
there is no ground-fault protection, these can cause a ground-fault
that sends current through the worker's body, resulting in
electrical burns, explosions, fire, or death.
 Solution
• Use ground-fault circuit interrupters (GFCI)s or have an assured
equipment grounding conductor program (AEGCP).
• Follow manufacturers' recommended testing procedure to insure GFCI
is working correctly.
• Use double-insulated tools and equipment, distinctively marked.
• Use tools and equipment according to the instructions included in their
listing, labeling or certification.
• Visually inspect all electrical equipment before use. Remove from
service any equipment with frayed cords, missing ground prongs,
cracked tool casings, etc. Apply a warning tag to any defective tool and
do not use it until the problem has been corrected.
 3. Path to ground missing or
discontinuous
• If the power supply to the electrical equipment at your site is not
grounded or the path has been broken, fault current may travel
through a worker's body, causing electrical burns or death. Even
when the power system is properly grounded, electrical
equipment can instantly change from safe to hazardous because of
extreme conditions and rough treatment.
 Solution
• Ground all power supply systems, electrical circuits, and electrical equipment.
• Frequently inspect electrical systems to insure that the path to ground is
continuous.
• Visually inspect all electrical equipment before use. Take any defective
equipment out of service.
• Do not remove ground prongs from cord- and plug-connected equipment or
extension cords.
• Use double-insulated tools and equipment, distinctively marked.
• Ground all exposed metal parts of equipment.
• Ground metal parts of the following non-electrical equipment, as specified by
the OSHA standard
• Frames and tracks of electrically operated cranes.
• Frames of non-electrically driven elevator cars to which electric conductors are attached.
• Hand-operated metal shifting ropes or cables of electric elevators.
• Metal partitions, grill work, and similar metal enclosures around equipment of over 1kV
between conductors.
 4. Equipment not used in manner
prescribed
• If electrical equipment is used in ways for which it is not designed,
you can no longer depend on safety features built in by the
manufacturer. This may damage your equipment and cause
employee injuries.
 Solution
• Use only equipment that is approved to meet standards set by the
government authority.
• Use all equipment according to the manufacturer's instructions.
• Do not modify cords or use them incorrectly.
• Be sure equipment that has been shop fabricated or altered is in
compliance.
 Improper use of extension and flexible
cords
• The normal wear and tear on extension and flexible cords at your
site can loosen or expose wires, creating hazardous conditions.
Cords that are not 3-wire type, not designed for hard-usage, or
that have been modified, increase your risk of contacting electrical
current.
 Solution
• Use factory-assembled cord sets.
• Use only extension cords that are 3-wire type.
• Use only extension cords that are marked with a designation code
for hard or extra-hard usage.
• Remove cords from receptacles by pulling on the plugs, not the
cords.
• Continually audit cords on-site. Any cords found not to be marked
for hard or extra-hard use, or which have been modified, must be
taken out of service immediately.
Radiation hazards
 Radiation hazards
• Radiation may be defined as energy traveling through space.
• Non-ionizing radiation is essential to life, but excessive exposures
will cause tissue damage.
• All forms of ionizing radiation have sufficient energy to ionize
atoms that may destabilize molecules within cells and lead to
tissue damage.
• Radiation sources are found in a wide range of occupational
settings.
• If radiation is not properly controlled it can be potentially
hazardous to the health of workers.
 Types of radiation
• Radiation can be classified into
1. Ionizing radiation and
2. Non-ionizing radiation
• Non-ionizing radiation is a form of radiation with less energy than
ionizing radiation. Unlike ionizing radiation, non-ionizing radiation does
not remove electrons from atoms or molecules of materials that include
air, water, and living tissue.
• Electromagnetic radiation ranging from extremely low frequency (ELF)
to ultraviolet (UV), in the electromagnetic spectrum comprise non-
ionizing radiation.
• The two types of ionizing radiation are particulate (alpha, beta,
neutrons) and electromagnetic (x-rays, gamma rays) radiation.
 Sources of non-ionising radiation
• Radiofrequency (RF) radiation used in many broadcast
and communications applications
• Microwaves used in the home kitchen
• Infrared radiation used in heat lamps
• Ultraviolet (UV) radiation from the sun and tanning beds
 Sources of ionising radiation
• It is present in the environment because naturally
occurring radioactive materials such as uranium, thorium,
actinium and potassium-40 exist in the material that
makes up planet Earth.
• There are three main sources of artificial ionising
radiation. They are:
1. Medical uses including diagnosis of many diseases and treatment of
cancer
2. Industrial uses, mainly in measurement and scientific research
3. Fallout from nuclear weapons testing and accidents around the world.
 Effect of non-ionizing radiation on
human body
• Exposure to intense, direct amounts of non-ionizing
radiation may result in damage to tissue due to heat. This
is not common and mainly of concern in the workplace for
those who work on large sources of non-ionizing radiation
devices and instruments.
• Risk can be due to the following Non-ionizing radiation
• Risk from ultraviolet (UV) radiation exposure
• Risk from exposure to radiofrequency (RF) and microwave
radiation
 Risk from ultraviolet (UV) radiation
exposure
• Ultraviolet (UV) radiation is a natural part of solar radiation,
and is released by black lights, tanning beds, and electric arc
lighting.
• Normal everyday levels of UV radiation can be helpful, and
produce vitamin D. The World Health Organization (WHO)
recommends 5 to 15 minutes of sun exposure 2 to 3 times a
week to get enough vitamin D.
• Too much UV radiation can cause skin burns, premature
aging of the skin, eye damage, and skin cancer. The
majority of skin cancers are caused by exposure to ultraviolet
radiation.
 Risk from exposure to radiofrequency
(RF) and microwave radiation
• Intense, direct exposure to radiofrequency (RF) or
microwave radiation may result in damage to tissue due to
heat. These more significant exposures could occur from
industrial devices in the workplace.
 Effect of ionizing radiation on human
body
• Workers may be exposed to ionizing radiation in several
ways, depending on their job tasks.
• The health effects of radiation dose depend on the type of
radiation emitted, the radiation dose received by a worker,
and the parts of the body that are exposed, among other
factors.
• Radiation dose depends on the duration of exposure, the
amount of radiation generated from the radiation source,
the distance from the radiation source, and the amount
and type of shielding in place.
 Situations in which a workers are
exposed to ionizing radiation
In general, radiation dose is received when a worker is:
• In close proximity to an unshielded or partially shielded
radiation source.
• Unprotected when near unshielded radiation-generating
machines (e.g., X-ray machine, accelerator, etc.) in operation.
• Unprotected when handling radioactive materials (e.g.,
radionuclides).
• In close proximity to surfaces or areas contaminated with
radioactive materials (e.g., from small spills or leaks).
• Contaminated with radioactive materials.
 Units of dose of radiation
• Radiation damage to tissue and/or organs depends on the dose
of radiation received, or the absorbed dose which is
expressed in a unit called the gray (Gy).
• The effective dose is used to measure ionizing radiation in
terms of the potential for causing harm. The sievert (Sv) is the
unit of effective dose that takes into account the type of radiation
and sensitivity of tissues and organs.
 Health effects of ionizing radiation
1. Beyond certain thresholds, radiation can impair the functioning of
tissues and/or organs and can produce acute effects such as skin
redness, hair loss, radiation burns, or acute radiation syndrome.
2. These effects are more severe at higher doses and higher dose rates.
For instance, the dose threshold for acute radiation syndrome is about
1 Sv (1000 mSv).

Acute radiation syndrome:

• Initial symptoms: Nausea, vomiting, and malaise.
• After latent period: Infections, fever, hemorrhage, loss of hair, diarrhea, loss of
body fluid, CNS effects
• High exposure dose leads to death
3. If the radiation dose is low and/or it is delivered over a
long period of time (low dose rate), the risk is
substantially lower because there is a greater likelihood
of repairing the damage. There is still a risk of long-term
effects such as cancer, however, that may appear years
or even decades later.
4. Epidemiological studies on populations exposed to
radiation, such as atomic bomb survivors or
radiotherapy patients, showed a significant increase of
cancer risk at doses above 100 mSv.
5. Prenatal exposure to ionizing radiation may induce
brain damage in foetuses following an acute dose
exceeding 100 mSv between weeks 8-15 of pregnancy
and 200 mSv between weeks 16-25 of pregnancy.
 Prevention of radiation hazards
1. Minimize time spent in areas with elevated radiation levels. Minimizing the
exposure time reduces a worker's dose from the radiation source.
2. Maximize distance from source(s) of radiation. A worker's radiation dose
decreases as the worker's distance from the source increases. For gamma
rays and X-rays, the radiation intensity is inversely proportional to the
square of the distance from the source (i.e., the inverse square law). This
means increasing the distance by a factor of 2 decreases the dose rate by a
factor of 4.
3. Use shielding for radiation sources (i.e., placing an appropriate shield
between source(s) of radiation and workers). Inserting the proper shielding
(e.g., lead, concrete, or special plastic shields depending on the type of
radiation) between a worker and a radiation source will greatly reduce or
eliminate the dose received by the worker.
4. Interlock Systems: A radiation safety interlock system is a device that automatically
shuts off or reduces the radiation emission rate from radiation-producing equipment
(gamma or X-ray equipment or accelerator). The purpose of a radiation safety
interlock system is to prevent worker exposure and injury from high radiation levels.
5. Administrative Controls: Administrative controls generally supplement
engineering controls. Examples of administrative controls include signage, warning
systems, and written operating procedures to prevent, reduce, or eliminate radiation
exposure. Operating procedures typically include both normal operating procedures
and emergency procedures (i.e., those for spills, leaks, and emergency evacuation).

6. Personal Protective Equipment: Personal Protective Equipment (PPE) is used to

prevent workers from becoming contaminated with radioactive material. It can be
used to prevent skin contamination with particulate radiation (alpha and beta
particles) and prevent inhalation of radioactive materials.
 Disposal of radioactive wastes
• The activities like mining and processing of uranium ore, fabrication of
nuclear fuel, generation of power in nuclear reactor, processing of spent
nuclear fuel, production and use of radionuclide for various industrial and
medical applications, research associating with radioactive material etc.
generates the different types of radioactive waste.
• Radioactive waste can be in gas, liquid or solid form, and its level of
radioactivity can vary.
• The waste can remain radioactive for a few hours or several months or even
hundreds of thousands of years.
• Depending on the level and nature of radioactivity, radioactive wastes can be
classified as exempt waste, Low & Intermediate level waste and High Level
Waste.
• The most important and advantageous property of radioactive waste is 'Its
radioactive hazard potential reduces with time depending on the half lives of
radionuclide present in the waste'. Such feature differentiates them
significantly from conventional chemical or industrial waste
• Effective management of radioactive waste involves segregation, characterization, handling,
treatment, conditioning and monitoring prior to final disposal.
Classification of radio active waste:
• Low Level Waste (LLW):
• LLW has very low radio activity such that it does not require shielding during handling and
transport, and is suitable for disposal in near surface facilities. LLW is generated from
hospitals and industry, as well as the nuclear fuel cycle. It comprises paper, rags, tools,
clothing, filters, etc., which contain small amounts of mostly short-lived radioactivity.
• Intermediate Level Waste (ILW):
• Intermediate-level waste (ILW) is more radioactive than LLW, but the heat it generates is
not sufficient to be taken into account in the design or selection of storage and disposal
facilities. Due to its higher levels of radioactivity, ILW requires some shielding.
• ILW typically comprises resins, chemical sludges, and metal fuel cladding, as well as
contaminated materials from reactor decommissioning.
• High-level waste (HLW:
• High-level waste (HLW) is sufficiently radioactive for its decay heat to increase its
temperature, and the temperature of its surroundings, significantly. As a result, HLW
requires cooling and shielding.
• The main source is used fuel that has been designated as waste.
 Disposal methods of Radio Active Waste
• Low Level Waste: Low-level waste is typically stored
on-site by licensees (near surface disposal), either until
it has decayed away and can be disposed of as ordinary
trash, or until amounts are large enough for shipment to
a low-level waste disposal site.
• Intermediate-level waste (ILW): Disposal could be by
emplacement in a facility constructed in caves, vaults, or
silos at least a few tens of meters below ground level.
• High Level Waste: First step is storage to allow decay of radioactivity and
heat, making handling much safer. After suitable processing the high level
waste is disposed in deep geological layers.
• Mined repositories: The most widely proposed deep geological
disposal concept is for a mined repository comprising tunnels or
caverns into which packaged waste would be placed. In some cases (e.g.
wet rock) the waste containers are then surrounded by a material such
as cement or clay (usually bentonite) to provide another barrier (called
buffer and/or backfill). The choice of waste container materials and
design, as well as the buffer/backfill material varies depending on the
type of waste to be contained and the nature of the host rock-type
available.
• Deep boreholes: The concept consists of drilling a borehole into
basement rock to a depth of up to about 5000 metres, emplacing waste
canisters containing radioactive waste in the lower 2000 metres of the
borehole, and sealing the upper 3000 metres of the borehole with
materials such as bentonite, asphalt or concrete.
 References
• https://www.osha.gov/
• https://www.ccohs.ca/
• https://www.arpansa.gov.au/
• https://www.epa.gov/
• https://www.hse.gov.uk/