Mumbai’s air quality dips after monsoon withdrawal

The moisture in the air during monsoon helps suppress dust particles, allowing for cleaner air. After the rains recede, it usually takes some time for the atmosphere to dry before pollution levels start to rise. But this year, the deterioration was immediate, an expert said

Mumbai: Days after the Indian Meteorological Department (IMD) announced monsoon withdrawal, Mumbai’s air quality has begun to deteriorate steadily, which is expected to worsen as the city moves closer to Diwali.

Mumbai, India - September 27, 2025: People going through the rain at Bandra in Mumbai, India, on Saturday, September 27, 2025. (Photo by Satish Bate/ Hindustan Times) (Hindustan Times)

According to data from the Central Pollution Control Board (CPCB), the city’s Air Quality Index (AQI) has shown a consistent decline over the past week. The month began with ‘good’ air quality levels, which slipped to the ‘satisfactory’ category between October 5 and 9. By Friday, the overall AQI had deteriorated to 134, and further rose to 152 on Saturday, placing it in the ‘moderate’ category.

The IMD declared the monsoon withdrawal on October 10. “The moisture in the air during monsoon helps suppress dust particles, allowing for cleaner air. After the rains recede, it usually takes some time for the atmosphere to dry before pollution levels start to rise. But this year, the deterioration was immediate,” said Dr Gufran Beig, chair professor at the National Institute of Advanced Sciences (NIAS). “This happened because wind movement along the western coast was sluggish, preventing dust particles from dispersing and causing them to remain trapped in the lower atmosphere,” he added.

On Sunday, the city’s overall AQI averaged 153, based on readings from 25 of the 30 continuous air quality monitoring stations in the city.

Except for Borivali East, with an AQI of 91, and Sion, with an AQI of 90, which remained in the ‘satisfactory’ range, 22 stations recorded AQI levels above 100. Deonar reported the poorest air quality, logging an AQI of 253. Areas such as Bandra Kurla Complex (AQI 194), Kandivali West (AQI 193), Vasai West (AQI 186) and Kandivali East (AQI 186) were nearing the ‘poor’ category threshold of 200.

As per CPCB standards, an AQI between 0–50 is considered good, 51–100 satisfactory, 101–200 moderate, 201–300 poor, 301–400 very poor, and above 400 severe.