World’s one of biggest killer : Air pollution



NATURE is a Blessing for all living organisms

It was the starting of earth when nature blessed us with many Ecosystem services  Everything organism have needed to survive and thrive, was delivered by the natural world around us: food to eat, oxygen to breath, water to drink, shelter to live and even natural cycles like climate. These all are the real needs of a life but a human never valued the nature deeds. Human use nature only for their selfishness but never give anything in revert to nature and today the condition of nature is merciful as human using all resources of earth without thinking. The rise of technology and industry may have distanced us superficially from nature, but it has not changed our reliance on the natural world. Everyone know how to use nature services but nobody know that how to give back. Our nature never demand anything but at least it’s a duty of human to maintain and respect nature resources as they are to live long and healthy life on this earth. Today it’s a big issue of life due to human activity to save our earth and pollution is the major cause for destroying flora and fauna of this beautiful earth.

Clean Air is life of living organism

We know, all living organisms need oxygen to survive on this earth and without oxygen nobody can survive but its not about only presence of oxygen but a need of clean air for breathing to be healthy.


I think its really tough to breathair with mixture of chemicals, toxic gases and other dangerous pollutants. Nowadays pollution of air is big issue in the entire world and only main reason of this disaster is due to anthropogenic.


All of us know about ‘pollution’ defined as entry of any harmful contaminant in the elements of earth which directly or indirectly destroying the resources of nature and also affecting the life of organisms. Here I am going to discuss one type of pollution called as air pollution.

Air pollution


Addition of any contaminant, particulate and toxic gases in the air of environment that can endanger human health and welfare of plants and animals. Substances which are able to cause pollution are called pollutants. Pollutants can be found in air anywhere – outdoors and indoors. According to the 2014 WHO report, air pollution in 2012 caused the death of 7 million individual in worldwide estimated by International Energy Agency.

 Main Reasons to worry about air pollution

  • It directly affects the environment parameters such as global warming
  • Also major reason of causing different diseases of human and animals
  • Air pollution also affects plants growth and their production

Pollutant are divided in two class

  • Primary pollutants (which are directly emitted in the atmosphere eg.SO2 CO NO etc.)
  • Secondary pollutants (which are first react with other component to become pollutant eg. Oxides of nitrogen )

Pollutants of air pollution divided in three groups:

  1. Criteria pollutant: air pollutants that have been regulated and used as indicators of air quality. Australia has set national standards for  criteria air pollutants in outdoor(ambient) air are:
pollutant description Source of spreading Effects
Carbon monoxide Gaseous
  •  Vehicle burning gasoline
  •  Indoor sources include wood burning stoves
  •  Dry cleaners
  •   Heart damage
  •   Headache reduce mental alertness and death
  •   smog
Sulfur dioxide   (SO2) Gaseous
  •   Coal burning power plants and industries
  •   Refineries


  •   eye irritation
  •   lung damage
  •   dead aquatic life
  •   reacts in atmosphere results in acid precipitation
  •   damage forests
Ozone ( O3) Gaseous
  •   vehicle exhaust
  •   respirator problem
  •   eye irritation
  •   skin problem
Particulate matters Very small particles of soot, dust, tiny droplets of liquid etc.
  •   power plants
  •   diesel engine
  •   steel industry
  •   windblown dust
  •  damage crops
  •   reduce visibility
  •   discolor building and statue
  •  eye irritation
Nitrogen oxide gaseous
  •   vehicles
  •   industrial boilers
  •   power plants
  •   natural gas pipelines
  •   form acid rain
  •   smog
  •   lung damage


  1. Air toxics: They are also called hazardous air pollutants. The living cities program defines air toxic as gaseous, particulate pollutant having toxicity and dangerous to human, plants and animal life.
  2. Biological pollutants: They are microbiological contaminants, such as moulds, spores any infected parts of human or other animals.

 Major effective pollutants in Air pollution

  • Carbon Monoxide (CO): It is a colorless, toxic and odorless gas produced due to incomplete combustion of carbonaceous fuel like natural gas, coal, wood, petrol, kerosene. It also spews out in car exhausts. Anthropogenic activities are responsible for about two third of carbon monoxide in air.

Mechanism of action in human: Carbon monoxide form hypoxic condition to show its adverse affect. It enters the body via inhalation and diffuses across the alveolar membrane same like oxygen. It first dissolve in blood then bind to hemoglobin (Hb) to form COHb, the binding of CO with Hb is more fast than oxygen molecule. Where it take more time to dissociate from Hb and leaving progressively less Hb available for carrying oxygen. The result is arterial hypoxemia.


  • Sulfur dioxide (SO2): It is a water soluble, colorless gas with odor that reacts with airborne solid particles. It is produced by burning of fossils and fuel, smelting, manufacturing of sulphuric acid, volcanic eruption. coal fired power plant are the world’s biggest source of sulfur dioxide. Major role in acid rain which is harmful for plants and animals. 
  • Nitrogen oxide: mainly nitrogen dioxide involve in pollution. It has brown color pungent suffocating odor. it is produced by vehicle engines and power plants. It play role in acid rain formation, smog and ozone.

Mechanism of action of SO2 and NO2 in acid rain formation: acid rain is form of precipitation that is acidic in nature due to high level of hydrogen ion (acidic pH). It affects human, plants aquatic animals and infrastructure. SO2 and NO2 after emissions react with water in the atmosphere to produce acids.


  • Particulate matter
    they are tiny particles of solid or liquid suspended in gas of size greater than 0.002 microns and smaller than 500 microns. Persistent free radicals react with airborne particulate and linked to cardiopulmonary diseases.

  • Ozone (O3): It is made up of three molecules of oxygen. Because of its chemical formulation, a single atom of oxygen is unstable. Ozone is not emitted directly into the air but it is form by reaction between oxides of nitrogen and volatile organic compounds in presence of sunlight. It is produced by emission from industry, gasoline vapor. Breathing ozone enhance the respiratory problem like asthma.


Sources of air pollution

 Air pollution by two sources: artificial and natural sources

Anthropogenic sources (artificial sources):

  • Mobile source include motor vehicle, aircraft and marine vessel.
  • Waste deposition in landfills, which generate methane harmful gas.
  • Military resources like nuclear weapons, toxic gases, germ welfare.
  • Industrial plants and factories produce large amount of pollutants. Industrial plants that produce metals such as aluminum and steel, refine petroleum, produce cement, synthesize plastics, or make other chemicals are among those that can produce harmful air pollution. One of example, case happened in Bhopal, India in December 1984, when a large chemical plant run by the Union Carbide company released a poisonous gas (methyl isocyanate) that hung over the local area, killing around 3000 people and injuring thousands more people.

 Natural sources:

  • Methane emitted naturally during digestion of food in animals
  • Volcanic eruption
  • Dust from natural resources
  • Radon gas from radioactive decay within the earth crust is a health hazard gas causing lung cancer.

Pollutants released from above sources are given below:

Transportation sources carbon monoxide ( CO ), lead ( Pb ), nitrogen oxides ( NOx ), ozone ( O3 )
Stationary sources carbon monoxide ( CO ), lead ( Pb ), nitrogen oxides ( NOx), particulate matter, sulfur dioxide (SO2)
Industrial processes carbon monoxide ( CO ), lead ( Pb ), nitrogen oxides ( NOx), particulate matter, sulfur dioxide (SO2)
Solid Waste Disposal carbon monoxide ( CO )
Miscellaneous ( forest fires, asphalt road paving, coal mining etc. ) carbon monoxide ( CO ), nitrogen oxides ( NOx), particulate matter, sulfur dioxide (SO2)

The following table indicates a table serves to illustrate the nationwide primary PM10 emission estimates from mobile and stationary sources, 1985 to 1993.

Effects of air pollution

It affects all living life and today the Major issue is control of air Pollution in the world. Air pollution not only affect human but also animals and plants life.

The magnitude of the London fog of 1952, which affected a large number of people, was the first incident that made people aware of the damage done to the atmosphere due to industrialization. The SPM levels increased manifold and resulted in over 4000 deaths. Indoor air pollution can be harmful to health as produce in close proximity of people. It is stated that a pollutant released indoors is many times has more exposure for lung than that released outdoors. According to WHO due to air pollution around two million people die prematurely each year and affect is more in developing country.

Health effects of air pollution on human

  • Cause disorder of lungs like chronic bronchitis, emphysema, asthma etc.
  • Cause different types of cancer, eg. Lung cancer, throat cancer, mouth cancer etc.
  • Cause irritation of eyes, nose, mouth and throat.
  • Reason of brain disorder such as, early exposure to air pollutant cause autism, schizophrenia.
  • Cause cardiovascular diseases by vasoconstriction like atherosclerosis.


Effects on animals and plants

  • Acid rain is major problem which affects life of aquatic organism as fish life in lakes and streams and also damage growth of plants
  • Destruction of air pollution causes vulnerability for animals to cause skin diseases.



Other effects of air pollution

Air pollution also effects infrastructure of building one of main example is Taj mahal. Area of taj mahal contain large amount of sulfur and nitrogen oxide due to presence of a large number of industry surrounding it and also polluted Yamuna river. Acid rain reacted with marble (calcium carbonate) of taj mahal.


Control measure for Air pollution

  • Using fuel with low sulfur and ash content
  • There should be air quality monitoring index
  • Maintaining a healthy distance between industrial and residential area.
  • The mining area should be planted with trees.
  • The coal fuel should be replaced with gas fuel.

 Equipment Used To Control Air Pollution

Air pollution can be reduced by the following approaches:

  • Ensuring sufficient supply of oxygen to the combustion chamber and adequate temperature so that the combustion is complete thereby eliminating much of the smoke consisting of partly burnt ashes and dust.
  • To use mechanical devices such as scrubbers, cyclones, bag houses and electro-static precipitators in manufacturing processes. The equipment used to remove particulates from the exhaust gases of electric power and industrial plants are shown below. All methods retain hazardous materials that must be disposed safely. Wet scrubber can additionally reduce sulphur dioxide emissions.






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A post graduate Master in Microbiology (Hons) from Guru Nanak Dev University - Amritsar with ARS NET, she is responsible for writing and reviewing microbiology article.