Mumbai had an annual average PM 2.5 concentration of 41.3 micrograms/cubic metre, which is nearly four times above the WHO limit, according to IQAir, a Swiss group that measures air quality levels based on concentration of Particulate Matter (PM) 2.5. In the last one year, there was improvement in the annual average of PM 2.5 for the city, which was 45.3 µg/m3 in 2019.
India was home to 35 of the world’s 50 most polluted cities, according to IQAir’s 2020 World Air Quality Report, which gathered data for 106 countries. The findings were based on the country’s annual average of PM 2.5 — airborne particles less than 2.5 microns in diameter.