Q.List out the major air pollutants and describe their effects on human beings.

Air pollution arises mainly from vehicular and industrial emissions and includes particulate and gaseous pollutants, which together cause a wide range of respiratory, cardiovascular, and other health effects in humans.

Major air pollutants:

1. Particulate matter (PM): Suspended particulate matter (SPM), and finer fractions PM10 and PM2.5 — solid/liquid particles like dust, soot, and smoke suspended in air, mainly from vehicle exhaust, industrial emissions, and construction.
2. Sulphur dioxide (SO2): Released by burning sulphur-containing fossil fuels (coal, diesel) in power plants and industries.
3. Nitrogen oxides (NOx, mainly NO and NO2): Produced by high-temperature combustion in vehicle engines and power plants.
4. Carbon monoxide (CO): An incomplete-combustion product of fossil fuels, chiefly from vehicular exhaust.
5. Carbon dioxide (CO2): From combustion of fossil fuels; a major greenhouse gas.
6. Ground-level (tropospheric) ozone (O3): A secondary pollutant formed by photochemical reactions between NOx and hydrocarbons in sunlight (main component of photochemical smog).
7. Hydrocarbons and volatile organic compounds: From unburnt fuel and industrial solvents.
8. Lead compounds and CFCs (chlorofluorocarbons): From leaded fuel/certain industries and from refrigerants/aerosols respectively.

Effects on human beings:

• Respiratory system: Particulate matter, SO2, and NOx irritate the respiratory tract, causing chronic bronchitis, asthma attacks, reduced lung function, and increased risk of lung cancer with long-term exposure.
• Cardiovascular system: Fine particulates and CO are linked to increased risk of heart disease and stroke.
• Carbon monoxide poisoning: CO binds to haemoglobin more strongly than oxygen (forming carboxyhaemoglobin), reducing the oxygen-carrying capacity of blood, causing headache, dizziness, and, at high concentrations, death. …