WHAT IS AIR POLLUTION?

Air pollution is the contamination of the atmosphere with the different harmful pollutant gases & chemical or biological agents which arise the problem for the breathing of species living on earth. It can be defined as the contamination of air present in the atmosphere with the different poisonous gases & pollutants which pose breathing problems to human beings, animals & different vegetation of earth. The different poisonous gases are carbon dioxide, carbon monoxide, nitrous oxide, methane, sulphur dioxide, CFCs i.e. chlorofluorocarbons etc. The air pollution is also the stage which occurs when the atmosphere is filled up with smog, smoke, dust, gases or fumes in more than acceptable levels or ratios causing breathing diseases & discomfort in sustaining of life over the earth. In simple words, the air pollution is defined as the stage of atmosphere when the natural composition of air is disturbed or changed by the accumulation of harmful chemicals or gases in the atmosphere. It can also be called as the disturbance in the balance of gases in the atmosphere from their original ratios is called air pollution. Air pollution is also a state of atmosphere when the natural cycles of carbon or nitrogen get reverse functioning & pollute environment. Some of the examples of air pollution are; emission of greenhouse & poisonous gases from the vehicles, from refrigerators or air conditioners used at homes or by burning of fossil fuels like coal, petroleum etc. & release of carbon dioxide in air from forest fires or deforestation; also air pollution results from release of poisonous & harmful radioactive gases from nuclear reactors. Air pollution also leads to the change in the atmosphere & many disorders, discomforts & health problems to humans & other living or non-living species which is caused due to the introduction of different chemical, biological or harmful particulates. Air pollution also results from natural sources such as due to dust blew from high wind speeds & fires originating in forests in drier periods.

Air pollution has increased levels since the beginning of an industrial revolution in the 19^th century in Europe as it led to increasing use of machines in industrial & agricultural works which emit harmful gases & poisonous chemicals in the air which pollutes the air & decreases its quality. The industries like leather industry, cement or brick industry, brick kilns, rice milling centres, petrochemical industries, steel making industries, coal mining industries, tar coal making factories etc. plays an important role in increasing the air pollution. Also, the increased rates of air pollution are due to the growing of more & more modern cities & way of living, a fast & rapid increase in the economic development of humans, increasing load of traffic on environment & mechanisation of industries due to use of new technologies which emit greenhouse gases in the atmosphere. Air pollution is the state of atmosphere observed when the gases & solid particles get mixed with air or present in the air. Air pollution is caused both of indoor as well as outdoor activities. This creates many health & skin problems for humans & wildlife species of animals, birds or plants. So, air pollution takes the atmosphere to a state where its natural or dynamic position is destroyed completely by the loss of its natural gaseous proportions or ratios & become polluted with more ratios of greenhouse & poisonous gases. Air pollution curses the earth in the manner as it destroys the protective layer of ozone in the stratosphere protecting from harmful UV rays from directly reaching the earth. Air pollution leads to some problems of kidneys & lungs which later result in cancer as well leading one towards death.

TYPE OF AIR POLLUTANTS

Pollutants or air pollutants are the solid or gaseous substances which when present in the atmosphere creates problems for environment health are known as pollutants or air pollutants. Pollutants can be defined as the naturals or artificial i.e. developed due to human work of development. Pollutants or air pollutants can be present in the state of gas, liquid, solid or mixture of these three states i.e. aerosol, smog, volatile organic or inorganic compounds etc. Mainly the air pollutants are classified on the basis of their development & pollution effects & types of organic or inorganic volatile compounds of harmful gases or chemicals etc. These chemicals are listed in detail below:

1. Primary pollutants: These can be defined as the pollutants which pollute the atmosphere and the environment directly after the emission from the source. These pollutants have the ultimate & deadly effect on the environment as these are harmful in their natural form or state. Primary pollutants do not need any special process or combining agent for action in the atmosphere to reverse the ratios of gases present in the atmosphere. These pollutants delete the natural properties of the atmospheric layer by affecting it on a large & long time scale. Primary pollutants result from the activities like emission from household products like CFCs, carbon dioxide & carbon monoxide from vehicles, sulphur dioxide, nitrous oxide & methane from the industrial sector & different poisonous chemical products from the volcanic eruptions & nuclear explosions & blasts. Some of these are listed below:

1. Nitrous oxides: These are the greenhouse gas which is released from different combustion processes & electric discharge processes. These gases are of reddish brown colour & lead to high temperature & also pollute the air with decreasing the ratio of normal gases in the atmosphere.
2. Sulphur oxides:  This group includes the harmful gases like sulphur dioxide (SO2) & sulphur monoxide (SO) which pollutes the air & atmosphere. These compounds of air pollution are released from the processes like industrial & volcanic eruptions. Also, the sulphur compounds are released from the combustion of different non-renewable sources of energy like coal etc. Sulphur compounds after reacting with other compounds also lead to acid rain over earth’s atmosphere which depletes the freshness & quality of air.
3. Carbon monoxide: It is the air polluting gas which is released from the sources of vehicle combustion & burning of fossil fuels. It represented by the formula CO. It is most dangerous gas. 
4. Carbon dioxide: It is the greenhouse gas which pollutes the air by decreasing the ratio of oxygen in the atmosphere.
5. Toxic heavy metals: The different toxic heavy metals which are primary pollutants resulting in air pollution are such as lead, mercury etc. & their different compounds.
6. Particulates & matter: These are the results of formation of a combination of small, tiny or fine particles leading to air pollution. For example the combination of different states of matter like gaseous particles with liquid particles such as aerosol which arises from the dust particles of volcanic eruptions, forest fires etc.
7. Chlorofluorocarbons or CFCs: These are air pollutants released from the different types of equipment like refrigerators, air conditioners or traffic smoke etc. It leads towards the depletion of the ozone layer by making holes in it due to the formation of hydrogen peroxide after the reaction.
8. Ammonia: It is also the air pollutant released from the different agricultural processes of crop production. It pollutes the air by decreasing the natural proportion of nitrogen in the air. It is represented by NH3.
9. Volatile compounds: the different volatile compounds like toluene, benzene, benzene hex chloride, xylene etc. also serves as primary air polluting devices as these combines with different greenhouse gases & pollutes the air.
10. Different radioactive materials i.e. wastes & gases: The radioactive gases like gamma rays, X-rays etc. & wastes like uranium, thorium etc. will pollute the air by their trapping action.
11. Different bad smelling gases from sources like sewage wastes, cattle dung, dumping grounds, fungal food products etc.

1. Secondary pollutants: These are the pollutants which are formed after the combination with primary pollutants & then pollute the air. Some of the examples of secondary pollutants are discussed below:

1. Smog: It is the secondary air pollutant which is formed after the combination of smoke with the fog. It creates the hazardous problems by polluting the air & forming the opaque layer leading to decrease in visibility in the atmosphere.
2. Different ozone & nitrogen compounds present on earth’s surface: These are also secondary air pollutants as these reacts with different gases & pollutes the air.
3. Secondary volatile compounds: These includes the pollutants formed after the reacting of primary volatile compounds like benzene, acetyl etc. with other organic compounds leading to air pollution. For example proxy acetyl nitrate or PAN.
4. Secondary particulates of matter: These are the air polluting materials formed with the combination of two different particulates leading to air pollution.
5. Propellants & asbestos are also included in secondary air pollutants.