Why is the air quality in Mumbai getting so bad?

Mumbai's air quality recently took a surprising turn for the worse, surpassing even Delhi's notorious pollution levels.

While winter usually brings smog to northern India after the monsoon season, Mumbai's air quality unexpectedly deteriorated.

The air quality index (AQI) reached an alarming 166, causing health concerns.

Last year, India made significant strides in environmental protection by pledging to achieve net-zero emissions by 2070.

What

• Air quality in Mumbai has suffered during the winter months, with more poor air quality days compared to previous years.
• Out of the past 92 winter days, 66 had poor air quality in 2022-23, a stark increase from the previous three years.
  Smog in Mumbai delayed trains and prompted a health advisory near Chhatrapati Shivaji Terminus, warning that it could cause respiratory problems.
• On many days, Mumbai's air quality even fell below Delhi's.

Why

• Slowdown of natural sea breeze: Mumbai's coastal location benefits from sea breezes, historically helping to control pollution. However, changing weather patterns due to global warming have disrupted this natural cleansing.

• Decrease in surface winds: Coastal cities like Mumbai typically experience wind reversals every 3-4 days with winds of 12-13 kmph, aiding in dispersing air pollutants and particulate matter. Recent years have seen wind speeds drop to around 4-5 kmph, leading to pollutants being trapped in the air.

• Vehicular emissions and solid waste: Vehicular emissions contribute to 20% of Mumbai's total emissions. Solid waste adds another 8% to the pollution levels.

Areas like Mankhurd, Govandi, and Deonar suffer from high air pollution levels, hosting many industrial units and experiencing heavy traffic congestion.

• Impact of construction activities: Extensive construction work, including buildings, metro projects, and road development, affects air quality. Emissions from construction activities and dust particles become trapped in the air due to slow wind speeds.

The National Clean Air Programme (NCAP) aims to reduce particulate matter concentration by 40% in covered cities by 2026. To achieve this goal, concerted efforts from the government, businesses, and the public are required, as Mumbai's air quality has been deteriorating.

As burning crop residue or 'stubble burning' continues in parts of Punjab and Haryana, Delhi's air quality has deteriorated. Over 2,500 cases of crop residue burning have been reported this year, though it's an improvement compared to the past two years.

On Wednesday morning, Delhi's air quality slightly improved, moving into the 'moderate' category with an Air Quality Index (AQI) of 190, according to SAFAR. The previous day, the AQI was in the 'poor' category at 231.