Air Pollutioj

7/30/2019 Air Pollutioj

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1. What is air pollution?

Air pollution is the change in the natural

composition of the air we breathe, beyond somedefined limits. Releasing harmful substances intothe atmosphere induces this change and it causesdamage to our health and environment. Natural

sources of air pollution include sea spray, volcanicactivity, forest fire, and dust storms. Anthropogenicsources include motor vehicles, industrialproduction processes, and power generation.


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2. What are the main airpollutants ?

(a) Particulate matter

(b) Nitrogen dioxide

(c) Ozone

(d) Lead

(e) Carbon monoxide

(f) Sulfur dioxide


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3. What are their healtheffects ?


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(a) Nitrogen dioxide

Particulate matter is the general term used to describe amixture of solid and liquid particles in air including dust,soot, smoke, and dirt. PM10 is particulate matter less than10 microns in aerodynamic diameter and is often called the

coarse fraction. PM2.5 is particulate matter less than 2.5microns (about 0.0001 inch) in aerodynamic diameter andis often called the fine fraction.

PM10 and PM2.5 particles are small enough to penetrate

into and accumulate in the respiratory system. Exposurecan cause respiratory morbidity, impaired lung function andirritation. It is also carcinogenic. This pollution is sometimesreferred to as black carbon pollution.


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(b) Nitrogen dioxide

Nitrogen dioxide (NO2) is a noxious gas, highlyreactive and it is formed when fuel is burned at

high temperature. The main sources are motorvehicles, power plants and industrial boilers.Nitrogen dioxide can cause respiratoryproblems. It can also take part in the chemicalreactions in the atmosphere to form corrosivenitric acid and can also react with sunlight toform ground level ozone.


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Ozone (O3) is a naturally occurring gas in the upperatmosphere (approximately 15km to 45km above theearths surface). In the upper atmosphere, ozone protectsthe earth from harmful ultraviolet rays from the sun.

However, ozone is also produced near ground level whenpollutants from motor vehicles and industrial processessuch as NOx and hydrocarbons react with sunlight.

At ground level, ozone is an oxidant that can irritate humannose, damage lungs and aggravate asthma. Ozone canalso damage crops and other vegetation. It is a keyingredient in photochemical smog formation.

(c) Ozone


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Lead is a heavy metal that was beingtraditionally used as an anti-knock agent ingasoline. Lead can also be released into the

atmosphere during metallurgical processesand is used in paints and ceramic industries.Lead accumulates in the body and can retardgrowth, hyperactivity, impaired hearing, and

even brain damage. Children are particularlysensitive to the effects of lead exposure,because of their high breathing rates.

(d) Lead


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(e) Carbon monoxide

Carbon monoxide (CO) is a gas that isslightly lighter than air and is formed whencarbon in fuel is not burned completely. In

urban areas, almost all CO is produced bymotor vehicles. Exposure to CO can disruptthe supply of oxygen to the body tissue,

cause neurobehavioral effects andcardiovascular problems.


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(f) Sulfur dioxide

Sulfur dioxide (SO2) is a gas that is oftenproduced in the burning of fossil fuels

containing sulfur It can cause respiratoryproblems and damage vegetation. Sulfurdioxide dissolves easily in water andtherefore can contribute to acid rain, once it

released into the atmosphere.


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The Air Quality Management Project(AQMP) has the following broad basedcomponents.

A. Component 1: Enforcement,Standards, and Pilot Control Programs

This component, essential for the long-

term success of emissions reductionmeasures, will include:(i) enforcement of emissions regulationsfor in-use vehicles;

(ii) development of vehicle emissions


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The enforcement of emission standardsfor grossly polluting vehicles, a crucialpart of regulations, is developing in

Bangladesh. When enforcement iscarried out, most diesel vehicles failemissions checks. Due to lack ofmanpower and poor inter-institutional

co-ordination between DoE and BRTA,emissions testing are done onlyinfrequently. Emissions test data are notbeing complied systematically or

analyzed. The current standards are

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Air Pollutioj