On Tuesday, the System of Air Quality Weather Forecasting and Research (SAFAR) recorded an air quality index (AQI) of 307 on Tuesday. An AQI between 301 and 400 is considered 'very poor', which, according to SAFAR, means people with heart or lung diseases such as asthma, chronic obstructive pulmonary disease, congestive heart disease or ischemic heart disease should avoid prolonged or heavy exertion. On Monday, the AQI recorded was 250.

Researchers from SAFAR said the increase in pollution levels could be attributed to winter conditions and high moisture levels. "Mumbai's humidity levels have remained high for the past few days and maximum temperatures are below normal, hence, the pollutants get trapped, making the air heavy. Low wind speeds have also not allowed the pollutants to disperse quickly," said GufranBeig, project director, SAFAR.

Among the 10 locations monitored by SAFAR, six recorded an AQI in the 'very poor' category and four remained in 'poor' category on Tuesday. Mazgaon was the most polluted at 395 and Worli was least polluted at 220.

On Tuesday, the minimum temperatures at Santacruz and Colaba were 16.6 and 20 degrees Celsius respectively, lower compared to Monday. The maximum temperatures were below normal with Santacruz and Colaba recording 29.7 and 28 degrees Celsius respectively—1.5 and 0.7 degrees below normal. The AQI is expected to improve to 302 on Wednesday, but it will still be in 'very poor' category.