India, Oct. 13 -- 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.

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,...