Pollution is the introduction of contaminants into an environment that causes instability, disorder, harm or discomfort to the ecosystem that is physical systems or living organisms. It is created mostly by human actions, but can also be a result of natural disasters. Pollution has a detrimental effect on any living organism in an environment, making it virtually impossible to sustain life. Pollution can take the form of chemical substances or energy, such as noise, heat, or light. Pollutants, the elements of pollution, can be foreign substances or energies, or naturally occurring; when naturally occurring, they are considered contaminants when they exceed natural levels. Bangladesh is apparently now in the grip of allsorts of pollution, like air pollution, soil pollution, water pollution and others.

Air PollutionAir pollution occurs when the air contains gases, dust, fumes or odour in harmful amounts. That is, amounts which could be harmful to the health or comfort of humans and animals or which could cause damage to plants and materials. Air pollution is actually the addition of any harmful substances to the atmosphere, which causes the damaging of the environment, human health and the quality of life.

According to WHO,  Air pollution is contamination of the indoor or outdoor environment by any chemical, physical or biological agent that modifies the natural characteristics of the atmosphere.

Air pollution is not only a local but also a global issue. So,now we see that what the main sources of air pollution are in globally and locally.

Types of Major Air Pollutants

Carbon oxides (CO, CO2)

Major sources: motor vehicle exhaust, burning of forests and grasslands, tobacco smoke, open fires/inefficient stoves for cooking

Nitrogen oxides and nitric acid (NO, NO2, HNO3)

colorless gas forms when N and O react at high combustion temps in auto engines and coal- burning power/industrial plants

Sulfur dioxide and sulfuric acid (SO2, H2SO4)

Colorless gas with irritating odor 1/3 from natural sources, 2/3 from human sources such as combustion of sulfur containing coal and oil refining and smelting

Particulates (SPM)

38% from human sources such as coal burning plants, motor vehicles, road construction, and tobacco smoke

Air PollutionGlobalIndustrialGaseous emissionThermal NaturalMarshlandsForestsLocalIndustrialGaseousThermalNaturalLandfillsGaseous

Ozone (O3)

Colorless, highly reactive gas, major ingredient of photochemical smog

Volatile organic compounds (VOCs)

VOC’s are organic compounds that exist as gases in the atmosphere or that evaporate into the atmosphere

There are two forms of air pollutants:-

Primary pollutants-harmful chemicals emitted directly into theair

Secondary pollutants- formed when primary pollutants react with one another and with other components of air to form new harmful chemicals

Factors that affect the Air Pollution :-

Natural Factors That Increase Air Pollution Urban buildings Hills and mountains High temperatures VOC emissions from certain trees and plants Grasshopper effect

Temperature inversions

Indoor Air Pollution

According to WHO indoor air pollution is world’s most serious air pollution problem especially for poor people in Developingcountries

Indoor cooking and heating Often higher concentration in buildings and cars Most time is spent indoors or in cars EPA – top cancer risk Tobacco smoke Formaldehyde Radioactive radon-222 gas Very small particles

Air pollution and the world

Exposure to air pollution is getting worse in parts of the world, especially industrializing countries, according to the WHO

Air pollution is not a problem that is limited to only one country. In fact, it is a worldwide epidemic that is much worse in some countries than in others.

In 2009, the 27 members of the European Union reported a cumulative drop in sulfur oxides by roughly 80% since 1990.

Despite major gains in lowering pollution throughout the European Union, some major metropolitan cities like London arecurrently suffering from some of the worst air quality they'veever seen.

A study by the World Health Organization reported in National Geographic News states that air pollution in China is related to around 656,000 deaths every year throughout the country.

The same report by the World Health Organization states that an average of 2 million people are killed worldwide every yeardue to air pollution.

In India, almost half of all monitored cities have above-average or critical levels of particulate matter pollution below 10 micrometers.

Now we will see that what is the present condition of air pollution of the world :-

Air Pollution and Bangladesh

Bangladesh is a developing and most densely populated country and also known as a third world country in the world. As its population limit cross the proportion of its area. So there exists a huge amount of air pollution.

A statistics show that The “air pollution” kills nearly 15,000 Bangladeshis each year according to Mr. Paul Martin, a bank environmental specialist in Dhaka 2001. This is released in the World Bank report saying Bangladesh could save between $200 million and $800 million per year. These amounts translate to about 0.7% to 3.0% of the gross national product if air pollution is reduced in just four major cities of Bangladesh.

An on-line forum called South Asia in 2001 mentioned that 6.5million people in four large cities of

Bangladesh suffer each year. Another at least 8.5 million cases have been observed with minor illnesses that did not require severe treatment. The major disease in Bangladesh is not diarrhea as often perceived

According to the Daily Star of Bangladesh, Swedish researchersgave details of the deadly heart attacks which may be more plausible problem among the people who spent decades living inheavily polluted areas.

Air Pollution Percentage of most Five Industrial Sectors of Bangladesh in the Year 2001

[Source: Research Work by Islam Faisal on “Industrial Pollution in Bangladesh” in the year 2002.]

An statistics show that the major air polluted areas of Bangladesh are

[air polluted area of Bangladesh]

Major Air Pollutants areas and sources of Bangladesh

Divisions Air

Pollution

PerchantegeDhaka 64%

Chittagong 15%Khulna 10%Sylhet 5%Rajshahi 4%Barishal 2%

Dhaka

Dhaka, one of the mega cities of the world, witnessed a very fast growth of urban population in recent times. Air pollutionin Dhaka city is reported to be serious and damaging to publichealth. In the winter of 1996-97, air pollution of Dhaka city became the severest when lead in the air was reported higher than in the atmosphere of any other place of the world . Concern over air pollution rate of Dhaka city ultimately led to the promulgation of National Ambient Air Quality Standards in Bangladesh 1997.

Highly polluting brickfields are still operating unabated across the country including on the outskirts of Dhaka posing serious health risks in this dry season, harming the nature and damaging arable land. Most of these conventional chimneys are baking bricks round the clock burning wood, tyres and low-quality coal. Replacing the chimneys with improved modern onescan relieve the situation to a considerable extent. But this issue has never been taken seriously by any government in the past two decades of rapid urbanisation.

Contribution of Vehicle Types to Emissions in Dhaka

Cars/Vans Auto-Rick Bus/Truck Others0

20

40

60

80

100

COHCNOx

%

Petrol-driven light duty vehicles and auto-rickshaws contributes 85% CO

Diesel buses and trucks contribute about 84% of total NOx TTW auto rickshaws contribute about half of total

unburned HC from all vehicles Diesel buses and trucks contribute about 45% and auto-

rickshaws 40% of total PM emissions SO2 emissions from vehicles are not very significant

compared to other pollutants.

Chittagong

Chittagong Port City is not only the 2nd largest city but alsothe commercial capital ofBangladesh and is expanding rapidly as well as experiencing environmental pressures likeother cities in Bangladesh. Air pollution problem is severe in the urban areas caused by both mobile as well as stationary sources. Mainly the two-stroke and diesel-run vehicles cause the severity of the problem by emitting highly contaminated exhausts. Considering severity of the problem, current study was undertaken to measure the air pollutants level in air of Chittagong city, Bangladesh. The heavy metals Zn, Pb, Mn, Cd, Cu and Co in suspended particulate matter (SPM) were determined at different locations of Chittagong city. The sampling locations were selected to reflect different influences from industrial and mobile sources in the highly populated center part of Chittagong city. Samplings were done during October and November 2008 from different areas of the metropolitan city of Chittagong city (Newmarket, Bahaddarhat, Nasirabad, General Electric Company (G.E.C.) Circle and Director's Office of Department of Environment, Bangladesh). High volume sampler was used for the determination of SPM and the different metal concentrations were measured by atomic absorption spectrophotometer (AAS). The average results of particulate matters and trace metals have been compared to national and international standards. The value of SPM in air of Chittagong city is higher than that of Threshold Limit Value (TLV) recommended by World Health Organization (WHO), Environmental Protection Agency (EPA), USA and Department of

Environment (DoE), Bangladesh. The metal concentrations of ambient air collected at different locations in Chittagong city is exceeded the threshold limit values and as a result the air of Chittagong city is considered polluted. Therefore, it is suggested that Government of Bangladesh should take proper steps to control the air pollution of Chittagong city.

Khulna

Khulna is the third biggest metropolitron city of Bangladesh and already called a medium industrial zone of Bangladesh. Because of available of river, raw products and transport there are many industry are existed in this division. Khalishpur, Noapara are the main industrial area where the factory emitted a huge amount of smoke called CO2 . The air environment of Khulna has been deteriorating rapidly during the last couple of years especially due to migration of highlypolluting 2-stroke engine banned vehicles from Dhaka.. In thiscity there is lack of solid waste management system. Almost every time we have seen that the waste have been dumped in the road side.

Air pollution can result from both human and natural actions. Natural events that pollute the air include forest fires, volcanic eruptions, wind erosion, pollen dispersal, evaporation of organic compounds and natural radioactivity. Pollution from natural occurrences are not very often.

Human activities that result in air pollution include:

1. Emissions from industries and manufacturing activitiesthere are long tubes (called chimneys) erected high into the air, with lots of smoke and fumes coming out of it. Waste incinerators, manufacturing industries and power plants emit high levels of carbon monoxide, organic compounds, and chemicals into the air. This happens almost everywhere that people live. Petroleum refineries also release lots of hydrocarbons into the air.

2. Burning Fossil FuelsAfter the industrial age, transportation has become a key partof our lives. Cars and heavy duty trucks, trains, shipping

vessels and airplanes all burn lots of fossil fuels to work. Emissions from automobile engines contain both primary and secondary pollutants. This is a major cause of pollution, and one that is very difficult to manage. This is because humans rely heavily on vehicles and engines for transporting people, good and services.

3. Household and Farming ChemicalsCrop dusting, fumigating homes, household cleaning products orpainting supplies, over the counter insect/pest killers, fertilizer dust emit harmful chemicals into the air and cause pollution. In many case, when we use these chemicals at home or offices with no or little ventilation, we may fall ill if we breathe them.

4. Petroleum

Petroleum is the driving force behind vehicles, however, this helpful substance is a major contributor to global air pollution. Petroleum releases carbon dioxide and nitrous oxideinto the air, which, when inhaled, can lead to illnesses.

5. Mining Operations

Operations, like mining and truck traffic, are some of the topcauses of air pollution. These activities release carbon monoxide, sulfur dioxide and nitrous oxide into the air, all of which contribute to development of smog and various health problems. Apart from these emissions, gold mines also release mercury particulates to the atmosphere. In excess amounts, mercury inhalation can lead to sensation disturbances, muscle weakness, respiratory problems, certain cancers, even death.

6.  Radioactive Fallout

Radioactive sources yield high amounts of energy, as well as harmful quantities of sulfur dioxide and several heavy metals into the air. In highly-industrialized cities, air pollution from radioactive fallout have been proven to create numerous environmental concerns, such as defoliation, deformation and undergrowth damage in trees, to name a few.

7. Chemical Pesticides

Pesticides are very helpful for farmers as they keep vermin, bacteria, and fungi that destroy their crops at bay. However, use of pesticides, especially those made from chemicals, also wreaks air pollution. Air pollution caused by pesticides can be fatal for animal, birds, even marine life, especially if the emissions already infiltrate their food sources.

8. Fertilizer Dust

Fertilizers are useful for farmers as they accelerate the growth of crops and plants. Nonetheless, the accumulation of fertilizer dust (even those made from organic ingredients) cangive way to the production of ammonia and nitrogen oxide, bothof which contribute to global warming and harmful acid rain. Such pollution also yields methane, a greenhouse gas. With thepresence of high amounts of methane in the atmosphere, the heat that should have been radiated back to the atmosphere arebounced back to earth, keeping the earth insulated.

Effects of Air pollution1. Respiratory and heart problems: The effects of Air pollution are alarming. They are known to create several respiratory and heart conditions along with Cancer, among other threats to the body. Several millions are known to have died due to direct or indirect effects of Air pollution. Children in areas exposed to air pollutants are said to commonly suffer from pneumonia and asthma.

2. Global warming: Another direct effect is the immediate alterations that the world is witnessing due to Global warming. With increased temperatures world wide, increase in sea levels and melting of ice from colder regions and icebergs, displacement and loss of habitat have already signaled an impending disaster if actions for preservation andnormalization aren’t undertaken soon.

3. Acid Rain: Harmful gases like nitrogen oxides and sulfur oxides are released into the atmosphere during the burning of fossil fuels. When it rains, the water droplets combines with

these air pollutants, becomes acidic and then falls on the ground in the form of acid rain. Acid rain can cause great damage to human, animals and crops.

4. Eutrophication: Eutrophication is a condition where high amount of nitrogen present in some pollutants gets developed on sea’s surface and turns itself into algae and and adverselyaffect fish, plants and animal species. The green colored algae that is present on lakes and ponds is due to presence ofthis chemical only.

5. Effect on Wildlife: Just like humans, animals also face some devastating affects of air pollution. Toxic chemicals present in the air can force wildlife species to move to new place and change their habitat. The toxic pollutants deposit over the surface of the water and can also affect sea animals.

6. Depletion of Ozone layer: Ozone exists in earth’s stratosphere and is responsible for protecting humans from harmful ultraviolet (UV) rays. Earth’s ozone layer is depleting due to the presence of chlorofluorocarbons, hydro chlorofluorocarbons in the atmosphere. As ozone layer will go thin, it will emit harmful rays back on earth and can cause skin and eye related problems. UV rays also have the capability to affect crops.

Solutions for Air Pollution1. Use public mode of transportation: Encourage people to use more and more public modes of transportation to reduce pollution. Also, try to make use of car pooling. If you and your colleagues come from the same locality and have same timings you can explore this option to save energy and money.

2. Conserve energy: Switch off fans and lights when you are going out. Large amount of fossil fuels are burnt to produce electricity. You can save the environment from degradation by reducing the amount of fossil fuels to be burned.

3. Understand the concept of Reduce, Reuse and Recycle: Do notthrow away items that are of no use to you. In-fact reuse themfor some other purpose. For e.g. you can use old jars to storecereals or pulses.

4. Emphasis on clean energy resources: Clean energy technologies like solar, wind and geothermal are on high thesedays. Governments of various countries have been providing grants to consumers who are interested in installing solar panels for their home. This will go a long way to curb air pollution.

5. Use energy efficient devices: CFL lights consume less electricity as against their counterparts. They live longer, consume less electricity, lower electricity bills and also help you to reduce pollution by consuming less energy.

Recommendation and Suggestions that reduce air pollutionCivilized people always feel the necessity of clean environment. But proper actions must be in place to assure clean environment. The atmosphere is under constant pressure from the green house gases that threaten to change the climateseverely. The following measures can be reviewed effectively and then adopted or implemented by the respective authorities beside private sector to provide clean atmosphere for the future generation:

i. Promote national energy efficiency and emission standards, and develop efficient, cost effective, and less polluting masstransit systems;

ii. Impose bar on importing leaded gasoline;

iii. Abolish 2-stroke engines and take steps to replace old and small vehicles by the large capacity vehicles having 4-stroke engines;

iv. Restrict usage of the vehicles older than 20 years having severe exhaust fumes;

v. Use proper lubricants that reduce emission levels and pollutants;

vi. Identify unfit vehicles via emission tests and introduce annual emission testing;

vii. Encourage people to use Compressed Natural Gas (CNG) or Liquid Petroleum Gas (LPG),Rechargeable Battery (recently being used by US) driven vehicles, etc.;

viii. Immediate relocate/shift the Industries (such as Tanneries, Battery, Pharmaceutical, Tobacco) away from Dhaka city suitable to initiate industrial belt or parkway;

ix. Extend training to the physicians and relevant personnel for potential patients;

x. Drivers of the vehicles require education on the reduction of emission;

xi. Introduce annual Seminar/Conference addressing detrimentaleffect of the pollution;

xii. Introduce proper disposition of the Industrial waste to avert degrading gases;

xiii. Create Public Awareness on Air Pollution through media such as videos, pamphlets, booklets, etc. beside radio and television programs;

xiv. Modernize power systems or power generating sub-stations;

xv. Reduce fossil-fuel combustion;

xvi. Save the forest and promote plantation within the city limits for ecological balance; and

xvii. Introduce ‘Strong Political Forum’ having agenda of saving the environment.

On our planet, the air we breathe is one of the most importantthings around us. It is a vital natural resource on which all life depends. An effective environmental planning and management process will help decision makers to formulate and implement realistic and effective strategies and action plans to improve air quality. These strategies and action plans haveto systematically address the short and long-term causes of air pollution and help a country to achieve a sustainable growth pattern.

References:-

1. Md Mahbubur Rahman, “Environmental Pollutionin Dhaka Cityand It’s Effects on Public Health”,2003

2. KM Nurul Huda, “Air Quantity Management Policy and Vehicle Emission Control”, 1998

3. 3. A survey report by British Geological Team on “Sustainable Development Networking Project”,Bangladesh, 1999

4. M. A. Zaman and Md. M. Rahman, “Impact of Indoor Air Pollutionon Health,” B.Sc. Engg. Thesis, Bangladesh Universityof Engineering and Technology, Mar. 2009, pp. 32-34.

5. 5.M. K. Paul, , “A Study of Continuous Profile of Specific Urban Pollutants,” M.Sc.Thesis, Bangladesh University of Engineering and Technology, Feb. 2002, p. 95.

6. Daniel A. Vallero. "Fundamentals of Air Pollution". Elsevier Academic Press.

7. ^ "Indoor air pollution and household energy". WHO and UNEP. 2011.

8. www.WHO.com

9. www.wikipedia.com

10. www.scriptbd.com