It's getting harder to breathe in Mumbai. Over the last few days, the Air Quality Index (AQI) has risen exponentially, with the System of Air Quality Forecasting and Research (SAFAR), a national initiative of the Ministry of Earth Sciences (MoES), recording AQI worse than Delhi. Several areas, including Mazgaon, Chembur and Malad, were reported to be in the “poor” category, recording an AQI of 200 and above.

Dr Anjal Prakash, research director, Bharti Institute of Public Policy, ISB, and Intergovernmental Panel on Climate Change lead author, breaks it down in layman’s terms. “Air pollution is caused by solid and liquid particles and certain gases that are suspended in the air. For Mumbai, two major primary pollutants are particulate matter [PM2.5 and PM10] and nitrogen dioxide [NO2],” he says in an email interview. On December 14, when this writer reached out to Dr Prakash, the PM2.5 concentration in Mumbai, he shared, was 2.1 times above the limit of the value recommended by the WHO’s 24-hour air quality guidelines (15 μg/m3).