UPSC Civil Services Model Paper 8

Air pollutants cause injury to all living organisms.
They reduce the growth and yield of crops and cause the premature death of plants.
Air pollutants also deleteriously affect the respiratory system of humans and of animals.
Harmful effects depend on the concentration of pollutants, duration of exposure, and the organism .
Smokestacks of thermal power plants, smelters, and other industries release particulate and gaseous air pollutants together with harmless gases, such as nitrogen, oxygen, etc.
These pollutants must be separated / filtered out before releasing the harmless gases into the atmosphere.