(1) Gaseous pollutants are gases which cause air pollution.
(2) Some common gaseous pollutants are CO2 , CO, SO2 , NO, NO2 , etc.
(3) Carbon dioxide (CO2 ) : It is a greenhouse gas which is continuously produced due to human activities such as burning of fossil fuels and rampant deforestation. Photosynthesis carried out by plants can balance CO2 : O2 ratio in the air, provided there is good green cover. CO2 is also removed from the air by weathering of silicate rocks forming limestone. Aeroplane traffic especially release lot of CO2 . CO2 is the main cause for global warming and climate change.
(4) Carbon monoxide (CO) : CO is a toxic gas produced by incomplete combustion of different fuels. Therefore, vehicular exhausts are the largest source of CO.
(5) Nitrogen dioxide (NO2 ) and nitrogen monoxide (NO) : Nitrogen oxides are released through automobiles and chemical industries as waste gases. NOa can form nitric acid after reacting with water vapour, this causes irritation to eyes and lungs. Injury to lungs, liver and kidneys is caused due to these gases.
