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Source: This post has been created based on the article “Climate change has made it harder to breathe in Mumbai” published in The Indian Express on 25th October 2023.
UPSC Syllabus Topic: GS Paper 3 Environment — Environmental pollution and degradation.
News: This article discusses the causes behind the recent degradation of air quality in Mumbai. It also suggests steps to tackle the rising challenge aggravated by climate change.
The Air Quality Index (AQI) in Mumbai has registered “moderate” or “poor” during the post-monsoon period for the second consecutive year.
What is Air Quality Index?
Notified by Central Pollution Control Board (CPCB), AQI considers 8 pollutants (PM10, PM2.5, NO2, SO2, CO, O3, NH3, and Pb). There are six AQI categories, namely Good, Satisfactory, Moderately polluted, Poor, Very Poor, and Severe.
Read more on AQI here: https://forumias.com/blog/air-quality-index-aqi-2/
How does Mumbai’s geography affect its air quality?
The coastal city has a natural cleaning mechanism.
Strong surface winds lead to faster dispersal of pollutants, and the strong sea-breeze sweeps away these particles from the land.
What are the reasons behind rising air pollution in Mumbai recently?
It is a result of a combination of factors. These include:
1) “Triple dip” La Niña:
Last winter, Mumbai experienced record-breaking particulate pollution, which was related to the unusual “triple dip” La Niña conditions— linked to climate change.
This had led to hardly any wind reversal from across the Arabian Sea, which would otherwise occur every 2 to 3 days and disperse pollutants in the air.
What is La Niña?
The weather pattern known as La Niña brings warmer-than-normal sea-surface temperatures (in red) to the southern Pacific Ocean around northern Australia, New Guinea, and the islands of Indonesia. The cooler sea-surface temperatures of La Niña (in blue) occur in the southern Pacific off the coast of South America.
A “triple-dip” La Niña is a multi-year cooling of the surface temperature of the equatorial Pacific Ocean. It’s called a “triple-dip” because it lasts for three consecutive northern hemisphere winters.
2) Delay in the withdrawal of monsoon:
The withdrawal of the monsoon was delayed till October. It plays a critical role in Mumbai’s air quality.
The withdrawal is always followed by an anti-cyclonic circulation above Mumbai leading to weak ventilation in the city.
3) Role of transport winds:
At the same time, the transport level winds (a measure of the average rate of the horizontal transport of air) transported pollutants towards Mumbai.
These winds encountered warmer winds which were laden with local dust. This dust-filled cloud pushed towards Mumbai and was halted because of the calm winds, deteriorating the city’s air quality.
4) PM10 pollution due to anthropogenic emissions:
PM10 stands for particulate matter with a diameter of 10 micrometers or less. It continues to be the major pollutant in the city. These coarser particles are largely a result of dust emissions.
Many development and construction activities are being undertaken across the city — these include the coastal corridor, the Metro and other digging activities.
What should be done to tackle this?
1) Prioritizing long-term mitigation planning: This should be based on mapping airsheds — areas where pollutants get trapped.
2) Tackling climate change: It is leading to extreme and unusual weather events leading to changes in the ecosystem.
3) Addressing anthropogenic emissions (root cause of air pollution)
4) Data- and science-driven approach: Data from reliable scientific sources should be taken into account.
5) Using green curtains: in construction sites to reduce dust.
6) Regular spraying of water: Dampens dust particles and prevents them from becoming airborne.
7) Fossil fuel-less transportation: Ensuring transitioning to electric vehicles.
8) Waste Management: Addressing solid waste management, cleaning up dumping grounds and industrial toxin management can improve air quality in the medium term.
Question for practice:
Climate change has worsened air pollution in India. Discuss with reference to the deteriorating air quality of Mumbai in recent years. What steps should be taken in order to tackle this challenge?
