Lockdown 4.0: Max dip in PM2.5 in Mumbai

The city’s air had the least amount of tiny and deadly pollutant particles during lockdown 4.0 as compared to Delhi, Ahmedabad, and Pune.

The city’s air had the least amount of tiny and deadly pollutant particles during lockdown 4.0 as compared to Delhi, Ahmedabad, and Pune.

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The concentration of PM2.5 — breathable particulate matter of 2.5 micron size that can easily enter the lungs and cause health ailments — was the lowest among four cities being monitored by air quality researchers during lockdown 4.0 as compared to the same period in 2019. Mumbai also showed the highest percentage decline in PM2.5 among major cities of the country.

Lockdown 4.0 from May 17 to May 31 was the fourth phase of nationwide clampdown to curb the spread of Covid-19 pandemic. The System of Air Quality Weather Forecasting and Research (SAFAR), which has been publishing regular reports of each lockdown period, released the latest one on Saturday.

According to the analysis, Mumbai recorded a 56% reduction in PM2.5 during the 15-day period as compared to the corresponding time last year. The reduction in Ahmedabad was 30%, Delhi 13%, and Pune 7%. Similarly the concentration for PM2.5 was 20 micrograms per cubic metre (μg/m3) in Mumbai during lockdown 4.0 as opposed to 48μg/m3 last year. It was 35μg/m3 and 31μg/m3 in Pune in 2020 and 2019 respectively. The concentration was the highest in Delhi with 53μg/m3 during lockdown 4.0 followed by Ahmedabad at 45μg/m3. In 2019, both cities recorded 65μg/m3 and 64μg/m3.

“Mumbai had much more cleaner air during lockdown 4.0 due to a combination of factors. Air quality improved as an effect of natural weather factors such as windy conditions and sporadic rain but most importantly the lockdown compliance was strictly followed as relaxations in Mumbai were minimal as compared to other cities,” said Gufran Beig, director, SAFAR.

Meanwhile, a similar trend was witnessed for PM10 (larger coarser particles) pollutants. Mumbai witnessed maximum reduction at 54% followed by Pune (32%), Ahmedabad (31%), and Delhi (16%). However, nitrogen dioxide (NO2) level — which results from vehicular emissions and fossil fuel burning — decline was the highest in Delhi and Pune at 49% each followed by Mumbai at 48% and Ahmedabad 22%. “This is because movement of vehicles began across all major cities in the fourth phase of lockdown,” said Beig adding, “Mumbai can expect clean air through the week but air quality may witness a spike if rainfall is not there.”

Meanwhile, a study by air quality research group UrbanEmissions.info found that over all four periods of lockdown, most Maharashtra cities, including Mumbai, had achieved 20%-30% reduction in PM2.5 levels as hoped to be achieved by the Centre’s National Clean Air Action Plan (NCAP). Maharashtra has 18 non-attainment cities, highest in India.