Topics Covered: Pollution related issues.
Why does air pollution rise in October every year?
Context:
Air pollution in Delhi and the whole of the Indo-Gangetic Plains is a complex phenomenon that is dependent on a variety of factors. But, every year in October, Delhi’s air quality starts to dip.
Factors responsible for this:
1. Withdrawal of monsoons:
During monsoons, the prevalent direction of wind is easterly. Once monsoon withdraws, the predominant direction of winds changes to north westerly.
- During summers, too, the direction of wind is north westerly and storms carry dust from Rajasthan and sometimes Pakistan and Afghanistan.
2. Dip in Temperatures:
As temperature dips, the inversion height — which is the layer beyond which pollutants cannot disperse into the upper layer of the atmosphere – is lowered. The concentration of pollutants in the air increases when this happens.
3. High-speed winds:
They are very effective at dispersing pollutants, but winters bring a dip in wind speed over all as compared to in summers.
4. Farm fires:
A 2015 source-apportionment study on Delhi’s air pollution conducted by IIT-Kanpur also states that 17-26% of all particulate matter in Delhi in winters is because of biomass burning.
5. Dust pollution:
Dry cold weather means dust is prevalent in the entire region, which does not see many rainy days between October and June. Dust pollution contributes to 56% of PM 10 and and the PM2.5 load at 59 t/d, the top contributors being road 38 % of PM 2.5 concentration.
6. Vehicular pollution:
It is the second biggest cause of pollution in winters. According to the IIT Kanpur study, 20 % of PM 2.5 in winters comes from vehicular pollution.
Measures to improve air quality:
- Improving public transport
- Limiting the number of polluting vehicles on the road
- Introducing less polluting fuel
- Strict emission regulations
- Improved efficiency for thermal power plants and industries
- Moving from diesel generators to rooftop solar
- Increased use of clean renewable energy
- Electric vehicles
- Removing dust from roads
- Regulating construction activities
- Stopping biomass burning, etc.
Sources: Indian Express.
