Mains Paper 3: Environment | Conservation, environmental pollution and degradation, environmental impact assessment
From UPSC perspective, the following things are important:
Prelims level: Particulars of the WHO report
Mains level: Delhi’s air pollution crisis
Mains 2015- Mumbai, Delhi and Kolkata are the three mega cities of the country but the air pollution is much more serious problem in Delhi as compared to the other two. Why is this so?
14 of the 15 highly polluted cities are in India
- A new global report on air pollution by the World Health Organisation (WHO) shows that 14 of the 15 cities with the highest levels of PM 2.5 pollutants in 2016 were in India
- These 14 towns and cities of northern India are stretching west to east from Jodhpur (No. 14) in Rajasthan to Gaya (No. 4), Patna (No. 5), and Muzaffarpur (No. 9) in Bihar
- Effectively then, the new WHO report identifies the Indo-Gangetic plain, along with Rajasthan and the Kashmir Valley, as having the worst air in the world
Why more pollution over Gangetic Plains?
- The Gangetic plains are like an enormous valley, trapped between the Himalayas in the north and the Vindhyas in the south, from where pollutants are unable to disperse very far.
- This region is land-locked — pollution cannot dissipate quickly — and does not have the advantage of the coast like Mumbai or Chennai.
- This region is one of the most densely populated in the world and the demand for energy sources, and the consequent burning of fuels is extremely high. This would release a large number of pollutants and particulate matter in the air.
- Also, a lot of the smaller cities in this region have poor waste management, there is a lot of burning, solid fuel use, they are moving from non-motorised to motorized transport.
- In this region, wind predominantly blows from north-west to east for most of the year carrying along with it pollutants generated elsewhere.
- The high levels of humidity in this region are very conducive to the formation of secondary aerosols. Water facilitates the reaction between the emitted gases whose molecules form clusters and slowly nucleate into particulate matters (PM)
- Stubble burning in NW India is also a major cause.