Air pollution: causes, effects and mitigation

Air pollution is the presence in the atmosphere of harmful substances (gases, particles, biological matter) in amounts that damage human health, living things, materials or climate. Main pollutants: particulate matter (PM10, PM2.5), carbon monoxide (CO), sulphur dioxide (SO₂), nitrogen oxides (NOₓ), ground-level ozone (O₃), hydrocarbons/VOCs and lead.

Causes (sources)

Natural sources: volcanic eruption, forest fires, dust storms, pollen, sea salt.

Man-made sources:

1. Vehicles – burning of petrol and diesel gives CO, NOₓ, hydrocarbons and PM; old, poorly maintained vehicles are the worst.
2. Industries and power plants – cement, brick kilns, thermal plants release SO₂, NOₓ and dust.
3. Burning of fossil fuels and biomass – coal, firewood, dung and agricultural residue.
4. Construction and road dust – unpaved and dug-up roads, building works.
5. Open burning of waste – plastics release dioxins and toxic smoke.
6. Agriculture – ammonia from fertilisers, methane from livestock and rice fields, pesticide spraying.
7. Indoor sources – cooking with firewood and kerosene, smoking.

Effects

On human health

• Respiratory diseases: asthma, bronchitis, COPD, pneumonia, lung cancer.
• Heart disease and stroke (PM2.5 enters blood).
• CO reduces oxygen carrying capacity of blood; lead harms the brain of children.
• Eye irritation, headache, reduced life expectancy.

On environment

• Acid rain from SO₂ and NOₓ damages crops, forests, lakes and buildings.
• Global warming and climate change from CO₂, CH₄, black carbon.
• Ozone layer depletion by CFCs.
• Smog and reduced visibility, affecting flights and tourism.
• Damage to plants (reduced photosynthesis) and to monuments and metal structures.

Economic – medical costs, lost working days, lower tourism.

Mitigation measures

1. Vehicle control – emission testing and green stickers, phasing out old vehicles, better fuel quality (Euro standards), promoting electric vehicles and public transport.
2. Industrial control – filters, electrostatic precipitators, scrubbers, tall stacks, cleaner brick kiln technology (zig-zag kilns).
3. Clean energy – hydropower, solar, wind, biogas, LPG/electric cooking instead of firewood.
4. Dust control – paving roads, covering construction sites, water sprinkling, timely completion of road works.
5. Waste management – ban open burning, recycling, composting, sanitary landfill.
6. Greenery – tree plantation along roads and green belts.
7. Monitoring and law – air quality monitoring stations, National Ambient Air Quality Standards, strict enforcement.
8. Awareness – masks during high pollution, public information on AQI, behaviour change.