Why in news?
Research led by IIT Madras (published in Science Advances) found that aerosols from vehicles, industries, and biomass burning are thickening winter fog across the Indo-Gangetic Plain.
Fog layers became 15–20% thicker, often reaching 400–600 meters in height, making them harder to disperse and worsening visibility.
Comparison: Aerosols vs Water Vapour in Climate Impact
| Factor |
Aerosols (Human + Natural) |
Water Vapour |
| Source |
Vehicles, industries, biomass burning, volcanoes, sea spray, desert dust |
Evaporation from oceans, lakes, soil, vegetation |
| Atmospheric Lifetime |
Days to weeks |
Hours to days (but constantly replenished) |
| Effect on Climate |
Scatter/absorb solar radiation, cool or warm depending on type |
Strong greenhouse gas, traps heat efficiently |
| Recent Findings |
Intensify fog, alter cloud reflectivity |
Contributes more to atmospheric heating than aerosols |
About Aerosols
- A suspension of fine solid particles or liquid droplets in air or another gas.
- Size Range: From a few nanometers (smaller than viruses) to tens of micrometers (about the width of a human hair).
- Examples: Mist, fog, dust, smoke, volcanic ash, sea spray.
- Bioaerosols: Tiny droplets carrying microorganisms, often linked to disease transmission.
Climate & Environmental Impact
- Radiation Balance: Aerosols scatter and absorb sunlight, cooling or warming the atmosphere depending on type.
- Cloud Formation: They act as cloud condensation nuclei, influencing rainfall and storm intensity.
- Visibility: High aerosol concentrations reduce visibility (e.g., smog, haze).
- Global Transport: Small particles can travel thousands of kilometers, impacting regions far from their source.
Health Effects
- Respiratory Issues: Fine aerosols (PM2.5) penetrate deep into lungs, linked to asthma, bronchitis, and cardiovascular disease.
- Infectious Spread: Bioaerosols (like droplets carrying viruses) are key in airborne disease transmission.
- Urban Smog: A mix of anthropogenic aerosols contributes to poor air quality in cities.
Key Considerations
- While some aerosols cool the Earth by reflecting sunlight, others (like black carbon) warm it by absorbing heat.
- Policy Challenge: Reducing harmful aerosols improves health but may alter climate balance.
- Research Importance: NASA and other agencies track aerosols via satellites to understand their global effects.
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