The revised WHO standard for particulate matter (PM) 2.5 is now eight times more stringent than the national guideline, indicating a daunting task ahead for policy makers and pollution monitors. A recent study found the PM 2.5 level may have acted as a catalyst in intensifying Covid infections in some wards.
Mumbai’s average concentration of PM 2.5 in the air during the restricted movement months of March to May this year was 40.3 micrograms per cubic metre (µg/m3), slightly higher than the national standard of 40 µg/m3. The earlier WHO standard recommended 10 µg/m3, which was revised to 5 µg/m3 on Wednesday.