What is Air Pollution.Causes and effects.

Air Pollution, Types, Sources and Effects

According to U. S. Environmental Protection Agency (USEPA) pollution is defined as presence of matter or energy whose nature, location, or quantity produce undesired environmental effects.

According to Keller (1988) pollution is a substance that is in the wrong place in the environment, in the wrong concentrations or at the wrong time such that it is damaging to living organisms or disrupts the normal functioning of the environment.

Some of the other definitions of the environmental pollution are:

The change in the physical, chemical and biological characteristics of the air, water and soil.

Pollution is the impairment of the quality of some portion of the environment by the accumulation of harmful substances.

As far as the word pollution is considered it comes from the Latin word polluere which stands for contamination. The contaminations are very harmful and are referred to as pollutants.

Fig.Air Pollution.

                                Pollutant

A pollutant is a substance present in greater than natural concentrations in the environment whereas a pollutant originates from a source, the source can be point or non-point. A point source originates from a known source and can be detected easily whereas non-point source pollutant does not originate from a known source it can be scattered over a large area and is difficult to locate it.

Pollutants inherent the potential of damaging the quality of air, water and land and make them unsuitable to use. The science of pollution may be divided among the study of air pollution, (atmosphere), water pollution (hydrosphere), soil pollution (geosphere), and life (biosphere).

Types of Air Pollutants

Environmental Protection Agency (EPA) and National Ambient Air Quality Standards (NAAQS) identified six pollutants these include:

Carbon monoxide:

Carbon monoxide is a colourless odorless and tasteless air pollutant produced through combustion. About 62% of this pollutant comes from vehicular exhaust rest of the percentage is contributed by forest fires, CO is a toxic gas causing headache, nausea or death depending on the concentration.

Sulfur dioxide:

The combustion of coal and other fossil fuels such as kerosene, petrol, and diesel emit sulfur dioxide. Exposure to this pollutant cause irritation of eyes nose and throat and cause acute respiratory disorders.

Nitrogen oxides:

The combustion of fossil fuels especially coal contribute nitrogen oxide.NO itself is not a pollutant when present in concentration already found in the atmosphere.in the presence of sunlight NO oxidized to form NO₂, it reacts with hydrocarbons to form photochemical smog. NO₂ also react with hydroxyl radical to form nitric acid (HNO3). NO is usually a colour less gas but when it is converted to NO₂ it becomes reddish brown colour.

Particulate matter:

Small sized solid particles and liquid droplets are collectively termed as particulates their size varies from 0.1 to 100 micro meter., their residence time in the atmosphere also varies from few seconds to several months this depends on size of particles and air turbulence. [articulate matter is injected into the atmosphere from a variety of sources such as volcanic eruption, sea salt spray, desert dust, pollen grains etc. they pose a serious threat to human life such as bronchitis, asthma, emphysema and particulate matter with size less than 10 micro meter may enter into blood stream after invading the lungs. They also reduce the visibility to a great extent.

Ozone:

The gaseous air pollutants especially nitrogen oxide react with sun rays to form ozone near the surface of earth. Ozone result in the development of respiratory complications.

Air pollution:

Simply an undesirable change in the physical, chemical and biological characteristics of the air is termed as air pollution. Or we can say that air pollution is the contamination of the atmosphere with the harmful byproducts of human activities. It can also result from the natural sources. These byproducts are not normal constituent of the atmosphere therefore they alter the composition of natural air furthermore these have a negative effect on the living and on living world as well, in this way we confer this air as polluted air and the whole phenomenon is known as air pollution.

 

Sources of air pollution

The sources of air pollution are broadly categorized into two types

Anthropogenic air pollution and natural air pollution

Anthropogenic air pollution:

Anthropogenic source contributes 95-98% of the carbon monoxide and thus making its concentration almost 100 times more than its normal value. Following categories are included under anthropogenic air pollution

(I) Mobile Sources

Also referred to as transportation source is considered as the chief source of air pollution. As we know that almost all the means of transportation such as airplanes, trains cars buses trucks etc., run on fossil fuels like petrol, diesel and kerosene. These fuels on combustion emits a spectrum of polluting gases like carbon monoxide, carbon dioxide, nitrogen oxides, oxides of Sulphur, hydrocarbons lead and particulate matter. These harmful and poisonous gases alter the composition of natural air and pollute it. with the increasing number of such mobile sources the concentration of these toxic gases also increasing at an alarming rate.

(II) Stationary sources

Stationary sources are divided into two major subcategories: point and area source; point sources consist of a single or multiple emission source and identified location point, while area sources are small emission sources that are widely distributed. These include

 1. Thermal power plants:

The cause of air pollution in these power plants is the combustion of coal as a source of energy the combustion of this fuel led to emission of air pollutants such as oxides of carbon, Sulphur, nitrogen, fly ash.

2. Industrial processes:

There are a number of industries such as textile, paper, leather, cement, steel manufacturing industries, oil refineries, food factories, Chemical and dye manufacturing and more which are using fossil fuels to carry out large scale activities to meet the growing demands of the growing population and hence becoming an alarming cause of air pollution by emitting various toxic gases into the atmosphere. the industrial emissions include smoke, soot, particulate matter and various gaseous and chemical pollutant.

3. Construction and demolition activities:

Dust, dirt and fine particulate matter is added into the atmosphere from construction and demolition activities on daily basis throughout the world.

4. Agricultural activities

These come under area sources where a number of lethal byproducts are emitted and become the part of ambient air these include ammonia gas, a number of chemical aerosols from the application of pesticides and fertilizers and much more.

5. Houses and offices:

In both the rural and urban settings the chief domestic air pollutants are, smoke dust, soot and various other chemicals and gases, the cause behind these pollutants include smoking, burning of coal, firewood, cow dung, kerosene etc., these pollutants contribute carbon monoxide, carbon dioxide, oxides of Sulphur etc., other domestic air pollutants include various chemicals which are sprayed in houses and offices as insecticides. Radon gas escaping from the cracks of house base or from mud walls contribute to indoor air pollution. Besides these fumes from paints, varnishes are also considered as lethal indoor air pollutants.

Natural Air Pollution

The natural sources of air pollution also add a number of pollutants into the air and hence contribute in air pollution, these include volcanic eruptions, forest fires, desert win blown dust, sea salt spray, pollen grains, fungal spores natural radioactive emissions. But majority of such pollutants if left undisturbed accommodate within the global ecological sinks in the form of oceans forests and soil. There are many types of effects that air pollutants cause. These effects are not only restricted to humans but also to flora, fauna and to the planet earth as well.

 

Effects of Air Pollution

The effects of air pollution are not confined to humans but also to animals, plants and to environment as well.

1. Mortality:

According to WHO 7 million people die every year as a result of air pollution.

2. Human ailments

Air pollution cause a number of human ailments these include

·        irritation in the eyes, lungs, nose and throat.

·        respiratory problems such as acute and chronic bronchitis, asthma and emphysema.

·        Skin damage

·        cardiovascular diseases

·        fatigue, headache and anxiety

·        Damage to reproductive organs

·        damage to nervous system.

3. Greenhouse effect:

Due to air pollution the pollutants such as carbon dioxide, methane oxides of nitrogen chlorofluro-carbons forms a blanket over the earth surface, by radiating back the long wave radiations coming back from the earth’s surface and results in the increasing of temperature this process is referred as greenhouse effect.

4. Accelerated global warming:

Global warming is a direct effect of greenhouse effect due to the accumulation of gases such as carbon dioxide and methane in the atmosphere. 

5. Climate change:

Air pollution also contributes to climate change.

6. Ozone Layer depletion:

Pollutants such as chlorofluro carbon depleted the ozone layer to a great extent.

7. Smog effect:

Also known as beret effect air pollution results in the formation of two types of smog photochemical and sulphurous smog which reduce the visibility and cause respiratory and sensory ailments and also become cause of fetal accidents.

8. Wildlife endangerment:

Air pollution causes many of the same complications in wildlife also and also result in the extinction of sensitive species.

9. Effect on marine life:

Polluted air loaded with toxic pollutants when deposited over the surface of water bodies effects the marine life.

10. Acid rain:

Air pollutants such as Sulphur dioxide and nitrogen oxide react with Water vapors present in the atmosphere to form nitric acid and sulphuric acid and fall down as acid precipitation in the form of rain, snow, or hails and affect the balance of chemical in soils and fresh water.

11. Effect on Flora:

The deposition of dust and dirt particles on leaf lamina results in the temporary or permanent closure of stomata and thus the process of photosynthesis is effected to great extent.

12. Economic effect:

According to World Bank air pollution costs 5 trillion U.S. Dollars per year.