Air Pollution: Sources, Impacts, and the Sustainability Challenge
1. The Lockdown Lesson: Clean Air is Possible
- During COVID-19 lockdown (2020), air pollution dropped dramatically across India.
- Delhi: PM2.5 levels fell by 70%
- Visible changes: blue skies, clearer horizons, stars reappeared
- Key Takeaway: Clean air is achievable without shutting down cities permanently—but requires systemic change.
2. What is Air Pollution?
Air pollution consists of tiny particles and gases—some natural, many human-made—that harm health and the environment.
Common Air Pollutants & Their Sources:
| Pollutant | Source | Health Impact |
|---|---|---|
| PM2.5 | Diesel exhaust, crop burning, cooking fires | Lung disease, heart issues, cancer |
| PM10 | Dust, construction, roads | Respiratory irritation |
| NOâ‚‚ | Vehicles, power plants | Asthma, ozone formation |
| SOâ‚‚ | Coal combustion, industrial boilers | Throat/lung irritation |
| O₃ (Ground-level) | Sunlight + NO₂ | Chest pain, coughing |
| Black Carbon | Incomplete combustion (diesel, wood) | Lung inflammation, climate warming |
3. Short-Lived Climate Pollutants (SLCPs)
What are SLCPs?
- Pollutants that don’t stay long in the atmosphere but cause immediate harm.
- Examples: Black carbon, methane, ozone, HFCs (from ACs/refrigerators)
Why They Matter:
- Methane: 80x more heat-trapping than COâ‚‚ (short-term)
- HFCs: Thousands of times more potent than COâ‚‚
- Black Carbon: Accelerates glacier melt, causes lung inflammation
SLCP Sources in India:
- 57% black carbon from residential cooking (biomass, dung)
- Diesel transport, crop burning, brick kilns, landfills
4. Particulate Matter (PM2.5) and Airsheds
What is PM2.5?
- Particles <2.5 microns (30x smaller than human hair)
- Penetrates lungs, enters bloodstream
Concept of Airshed:
- A geographic zone where air pollutants mix and accumulate
- Pollution travels across cities, states, and borders
- Example: Stubble burning in Punjab/Haryana affects Delhi’s air
Regional Impact:
- Indo-Gangetic Plain has highest PM2.5 concentrations
- Requires regional collaboration for effective management
5. Health and Social Impacts
Statistics:
- 1.6 million premature deaths in India (2019) due to air pollution (Lancet)
- More deaths than from tobacco or malnutrition
Affected Groups:
- Children: weaker lungs, missed school days
- Elderly: higher risk of strokes, heart attacks
- Poor communities: most exposed, least protected
Social Justice Dimension:
- Slum residents, informal workers, rural households using firewood suffer most
- Industrial polluters often live far from worst effects
6. Link to Climate Change
- Reducing air pollution = cooling the planet
- Black carbon is both a health hazard and a climate warmer
- Clean air actions contribute to climate mitigation
7. Key Takeaways
- Air pollution is a regional, transboundary issue
- SLCPs offer quick wins: reducing them brings fast health and climate benefits
- Social equity must be central to pollution control policies
- Clean air is achievable with systemic, collaborative action
Exam Tip
Focus on the types and sources of air pollutants (especially PM2.5 and SLCPs), the concept of airsheds, and the social and health impacts of air pollution. Use data from the lockdown to illustrate the possibility of cleaner air. Emphasize the link between air pollution and climate change, and the need for regional and equity-focused solutions.