MANPREET KAUR

B TECH BIOTECHNOLOGY – 5TH SEM

 AIR QUALITY
STANDARD AND
MONITORING
 AIR POLLUTION
• Definition – Air pollution is define as
‘Excessive concentration of foreign matter in
air ,which adversely affects the well being of
individuals or cause damage to the property “
 CHEMICAL COMPOSITION OF AIR
NAME SYMBOL %BY VOLUME
Nitrogen N2 78.084%
Oxygen O2 20.9476%
Argon Ar 0.934%
Carbon Dioxide CO2 0.0314%
Neon Ne 0.001818%
Methane CH4 0.0002%
Helium He 0.000524%
Krypton Kr 0.000114%
Hydrogen H2 0.00005%
Xenon Xe 0.0000087%
What is air quality ?
• Air quality refers to the condition of the air within our surrounding.
Good air quality pertains to the degree which the air is clean ,clear
and free from pollutants such as smoke ,dust and smog among other
gaseous impurities in the air . Air quality is determined by assessing a
variety of pollution indicators. Clean air is essential to maintaining the
delicate balance of life on this planet – not just for humans ,but
wildlife , vegetation, water and soil . Poor air quality is a result of a
number of factors ,including emissions from various sources , both
natural and “ human-caused.”
How is Air Quality Degraded ?
• Air quality is degraded by the day to day emissions from different air
pollution sources. These include: stationary sources such as power
plants, manufacturing facilities, smelters, motor machines, and
burning wood and coal ;mobile sources such as trucks, buses and
cars; and natural sources such as volcanic eruptions , and windstorm
dust. The pollutants from these sources are released into air which
can affect the health of humans, animals and our environment.
• The quality of air depends on 3 factors: the amount of air pollutants,
the rate at which they are released in atmosphere, and how long they
are trapped in an area.
• The air pollution sources emit a wide range of pollutants classified
under different categories that include SO2, particulate matter,
Hydrocarbons, VOC( volatile organic compounds),Lead, CO2,
CO(carbon monoxide),Nitrogen Oxides, and smog. Many of these air
pollutants occur as gases, but some are very tiny solid particles , such
as dust , smoke or soot .Air pollution from various sources can affect
indoor air as well. Removing the pollutants from indoor air can
improve the quality of your indoor air pollutants include cigarette
smoke, mould, dust mites, pet dander, formaldehyde, volatile organic
compound (VOC), and radon gases.
• If air pollutants are in an area with good airflow, they will mix with air
and quickly disperse. Air pollutants tend to remain in the air when
there are certain conditions like light winds or mountains that restrict
the transport of these pollutants away from an area. When this
happens , pollution concentrations can increase rapidly.
Measurements of air quality generally fall into three
classes:
• -Measurements of Emissions –also called source sampling-when a
particular emission source is measured, generally by on the spot tests.

• Meteorological Measurement – Measures meteorological factors

that show how pollutants are transferred from source to recipient.

• Ambient Air Quality- Measures the quality of all the air in a

particular place. Almost all the evidence of health effects is based on
these measurements.
Also now have:
• Industrial Hygiene sampling – for testing the air quality inside
of factories and places of work.

• Residential Indoor sampling –to evaluate the quality of air in

living spaces.
Air Sampling Techniques
• Most air pollution monitoring equipment performs the act of
sampling and analysis in one action = real time measurement.

• Older equipment = intermittent sampling (time lag between when the

sample was obtained and when data was available).

• Almost all gaseous pollutants are monitored by real time analysis –

Particulate pollutants are still mostly monitored by intermittent
sampling ,even though real time methods available.
• When obtaining a sample for air pollution analysis
- Should be sufficient sample for analysis. Most pollutants, very low
levels and require a large volume of gas for accurate measurement.
- Pollutants in very small quantities are easy to contaminate. Take care
to purge sampling containers if grab samples are used.
- Collection and analysis limitations may require collection over
extended periods means data may only be a 24 hr avg.
- Real time produces so much data – are often set to give hourly avg. to
make data more understandable.
Air Sampling Systems
require gases or particles to be drawn to the surface of a collecting
medium or a sensor
sampling trains, which may include a vacuum trap, a flow regulator
and a collecting device or sensing unit
Sampling trains for gases may also utilize filters to present particles
from entering the collection unit
Air Sampling Systems
Air Sampling Procedures
conducted by static, grab, intermittent or continuous procedures
first air monitoring used static sampling –simple and cheap –requires
days for data e.g. deposit gauge
Grab sampling not commonly used to monitor ambient air quality -
use bladders of syringes
Air Quality Standards And Monitoring
• NAAQM( National Ambient Air Quality Monitoring) network is
operated through NEERI ( National environmental Engineering
Research Institute) and CPCB(Central pollution Control Board).
• Ambient Air Quality Status is described as Low(L), Moderate(M),
High(H), Critical(C).
• Two types of NAAQS : Primary and Secondary
Ambient Air Quality Standards
Monitoring of air pollution
• Monitoring is done to keep a track on quality of air with a view to
collect information and improve it.
• The best indicators are – SO2, smoke and suspended particles.
• These are monitored on a daily basis and the results are collected by a
central agency.
1. Sulphur Dioxide – Major contaminant in urban and industrial areas
which is measured by colorimetry, conductivity, coulometry and
amperometry.
2. Grit and dust measurement – Deposit gauge collect grit, dust and
other solids which are analysed monthly.s
3. Smoke index – A known volume of air is filtered through a white
filter paper under specified conditions and the stain is measured by
photoelectric meter and expressed as μg/m3 of air.
4. Haze – It is traditionally an atmospheric phenomenon where dust,
smoke and other dry particles obscure the clarity of the sky.
5. Air quality index – It is an index (that is, a numerical value or ratio
derived from a series of observations) for reporting daily air quality.
.It tells us how clean or polluted our air is, and what associated health
effects might be a concern for us.
• AQI calculated for five major air pollutants regulated by the clean Air
Act: ground –level ozone, particle pollution (also known as particulate
matter),carbon monoxide, sulphur dioxide, and nitrogen dioxide.
• The WHO(1987) in its publication air quality for guidelines for Europe
has described approved methods of determining the concentration of
common air pollutants and their health hazards.
• The emphasis in the guideline is placed on exposure since this
element that can be controlled to lessen the dose and hence lessen
the response.
Limitations of Air Quality Index(AQI)
• Most air contaminants do not have an associated AQI.
• The AQI can worsen (go up )due to lack of dilution of air emission by
fresh air.
• Stagnant air, due to anticyclone or temperature inversion, or lack of
winds prevents dilution.
Air pollution monitoring in India
• The national air quality monitoring programme sponsored by the
central pollution control board since 1990 has generated database
over last 14 years in 10 major Indian cities.
• The trend analysis showed that suspended particulate matter (SPM)
exceeds the CPCB standards in all the cities of the time throughout
the year.
• The concentration ratio of p<10 fraction (human respirable
particles )to the ratio SPM varies between 30% to 60%, with coastal
cities showing highest percentages.
Control of Air Pollution
• Air pollution cannot be fully abated but can be controlled if
certain measures are taken.
• Controlling measures for air pollution can be mainly divided into
• Preventive measures
• Control measures
• i.e. Control of gaseous/particulate pollutants
• From industry/automobiles using equipments.
Preventive Measures
• These measures are mainly aimed at correction right at the source so
there will be lesser amount of pollutant emitted from the
industry/automobiles.
• Some of the important preventive measures are
• Using low sulphur coal in power plants
• Using natural gas in place of coal for power generation.
• Using LPG/ CNG instead of diesel or petrol in automobiles.
• “Modifications” in industrial processes and/ or equipments to reduce
the emissions
• Section of suitable site and zoning for industrial unit:
Zoning means setting aside separate areas for industries so that they
are far from residential areas. This will help in proper dispersion of
pollutants resulting in lower concentration of pollutants in the air of
residential areas.
• By using proper environment impact studies before setting
the industry.
Control Measures
• The most common method of eliminating or reducing pollutants to an
acceptable level includes:
• Collecting the pollutants by using equipments to prevent its escape into
atmosphere.
• Destroying the pollutants by thermal or catalytic combustion.
• Changing the pollution to less toxic form.
• By releasing the pollutants through tall chimneys for greater dispersion. Tall
chimneys will liberate the pollutants beyond the inversion layer there by
reducing the concentration of pollutants near the source.But the liberated
pollutants will settle somewhere and cause of the air pollutants even far away
from the source.
Control of Air Pollution
Prevention is always better than cure.
• one can prevent the air pollution. For this purpose some of the examples
are as follows:-
• (i) Controlling the spread of coal dust by sprinkling water on it before
handling in a thermal power plant.
• (ii) Preventive maintenance by repairing leaky valves in advance so as to
prevent the leakages of the harmful gases in air.
• (iii) Applying zoning to distribute the impact of air pollution in a community.
• (iv) Selection of proper material. For example using low sulfur coal reduces
the problem.
Control Of Air Pollution
• In addition to the preventive measures one have to have control technologies as
follows.
• Depending upon the situation different control technologies are adopted. For dealing
with the particulate matter the following control technologies are used.
• Settling chambers
• Cyclone separators
• Fabric filters
• Electrostatic precipitators
• Wet collector (scrubbers)
• The first two of the above are used for coarse particulates where as the other three
are used for fine particulates.
Air pollution Control
• The atmosphere like a river, do possesses self-cleansing properties,
which continuously clean and remove the pollutants from the
atmosphere under natural processes. So long as the pollutants
discharged by man into the environment, is lower than the natural
cleansing capacity of the environment, we live happily without any air
pollution. But as when the discharged pollutants exceed the natural
cleansing capacity, our environment becomes polluted, Attempts are
then made to reduce the emission of pollutants from the automobiles
of factories by adopting mechanical means, or by using high rise
chimneys for better dispersion and dilution of pollutants over a longer
range of environment.
The Natural Self-Cleansing Properties of the
Environment
• The Various natural properties, which continuously clean the environment,
automatically, are:
• Dispersion
• Gravitational Settling with or without flocculation of particles
• Absorption including washout and scavenging;
• Rainout and
• Adsorption
• All these processes, naturally occur periodically in the ambient air, thereby
removing or reducing the various pollutants entering the air. These
processes are briefly discussed below:
• Dispersion: Dispersion of pollutants by winds reduces the
concentration of air pollutants at one place, although in
the strict sense, it does not remove them from the
environment as a whole. This mechanism is therefore a
diluting mechanism only.
• Gravitational Settling: Gravitational settling is the most
important natural mechanism, under which large heavy
particles from ambient air settles down on buildings, trees
and other objects. This generally happens for the particles
which are larger than 50μ in size. It also helps in removing
flocculated particles formed by uniting of smaller particles
over larger particles.
REFERENCES -
• Https://www.slideshare.net/gauravhtandon1/air-pollution-33417151
• www.conserve-energy-future.com
• Air quality sampling and monitoring by Civil Engineer BiBhabasu
Mohanty
• Sewage Disposal and Air Pollution Engineering by Prof. S.K. Garg