Explain the effects of any two air pollutant on human health and properties.
Carbon monoxide (CO)
It is colourless, odourless, tasteless gas.It has no effect at normal concentration (0.1ppm) but at higher conc. It seriously affects the human metabolism.
Sources
- Natural sources such as Volcanic eruption, natural gas emissions, electrical discharge during cloud forming, marsh gas production etc. contribute a small amount of CO in the atmosphere.
- Transportation sources contribute about 64% of CO in air.
- Forest fire and agricultural burning contribute about 17 % of in air.
- Industrial processes such as electric furnace and blast furnaces in iron and steel industries, Petroleum refining, Paper industry, Gas manufacture, Coal mining etc.
Effect
- It reduces the oxygen carrying capacity of the blood by selectively combining with haemoglobin forming carboxyhemoglobin. This causes giddiness, laziness, and exhaustion.
- It reduces vision and causes cardiovascular disorders.
- CO is a very dangerous asphyxiate and its high levels are fatal to human life.
- It may cause coma, respiratory failure and even death.
Oxides of nitrogen
NOx group include six different oxides of nitrogen (NO, NO2, N2O, N2O3, N2O4, N2O5). Nitric oxide and nitrogen oxide are very important pollutant. NO is colourless, odourless gas but is NO2 reddish brown and have suffocating odour.
Sources
- Fuel combustion in automobiles and industries.
- Lightening
- Forest fire
- Bacterial decomposition of organic matter
Effects
- Nitric oxide combines with haemoglobin and reduces the oxygen carrying capacity of blood.
- NO2 is more toxic then NO and may affect lungs and cause bronchitis.
- NO2 is reacting with atmospheric moisture to form nitric acid causes acid rain and affects vegetables and metals.
Effects on property and material
- SO2 in the presence of oxygen and moisture is converted into H2SO4 acid. Deposition of this acid on metal parts of building roofs, railway tracks, metal on bridges cause corrosion.
- H2SO4 acid deposition reacts with limestone, marble and other building materials to cause deterioration and disfigure the building materials.
- Pollutants like SO2, O3, H2S and aerosols damage protective coating and paints of the surface.
- Damage of textile dyes and textile fibers is caused by SOX, NO, and O3 and PAN cause cracking of rubber tyres and various forms of electrical insulation. Deterioration of leather and paper due to H2SO4 deposition.
- Soiling increases cost of cleaning shirts and other wears, windows, curtains, building surfaces.
- SPM of large size carried by wind wave at high speed when they strike any surface deterioration takes place. Dust storm has this tendency of causing deterioration.
