PM2.5 pollution in Mumbai dipped 9% between 2019 and 2020: Report

The average daily concentration of PM2.5 in the city at stood 41.3ug/m3 for 2020, according to a report released on Tuesday by Swedish technology company IQ AirVisual.

The average daily concentration of PM2.5 in the city at stood 41.3ug/m3 for 2020, according to a report released on Tuesday by Swedish technology company IQ AirVisual. This is lower than the daily average of 45.3ug/m3 recorded in 2019. However, it is slightly higher than the safe annual threshold of 40ug/m3 as per India’s national ambient air quality standards.

Experts said the drop in pollution can be attributed largely due to the Covid-19-induced lockdown which brought a wide range of emissions to a halt. (HT FILE)

According to the latest World Air Quality Report, Mumbai noted an “observed” reduction of 9% in concentration of PM2.5 pollutants between 2019 and 2020. However, when accounting for “weather correction” — a mathematical factor which aims to eliminate the influence of weather on observed air pollution data — the reduction worked out to be about 13%, as per the report.

Experts said this can be attributed largely due to the Covid-19-induced lockdown which brought a wide range of emissions to a halt. Similar reductions were noted in several Indian cities “with 63% reporting direct improvements over 2019 averages” with regard to PM2.5 levels.

February remained the most polluted month in Mumbai with respect to PM2.5 pollution, clocking an average daily concentration of 73.3ug/m3, above the daily safe threshold of 60ug/m3 as per India’s NAAQS. June was the cleanest month, recording an average daily PM2.5 concentration of 15.9ug/m3. However, during the last quarter of 2020, PM2.5 levels returned to the same levels as the previous year, the data shows.

Requesting anonymity, a spokesperson for System of Air Quality and Weather Forecasting And Research (SAFAR) — which maintains an observational network of 10 air quality monitoring stations across Mumbai and Navi Mumbai — said, “The results are not surprising given that most of Mumbai’s prominent emissions sources, such as vehicles and construction activity, were essentially absent during the lockdown months. But I would not celebrate the findings. If you see the monthly data, the level of PM2.5 again rises sharply in October, November and December as lockdown restrictions were lifted. This report has given us some idea of how we can reduce particulate matter pollution, but finding city-specific solutions is now up to us.”

Mumbai remained the third most polluted among major Indian cities featured in the World Air Quality Report (behind Delhi and Kolkata). Bengaluru, Hyderabad and Chennai, meanwhile, all recorded cleaner air than Mumbai in 2020, with average daily PM2.5 levels ranging from 26ug/m3 to 35ug/m3.

Overall, Mumbai saw average daily concentrations of PM.25 above or equal to 25ug/m3 on 64% of days during 2020. A similar metric for comparison with the previous year’s World Air Quality Report was not provided.

The report also shows that, over the past six years, there has been a steady decline in the city’s annual average concentration of PM2.5 — from just under 50ug/m3 in 2015 to 41.3ug/m3 in 2020. The report does not, however, offer possible explanations for this trend.

The report states that this progress is “only marginally attributable” to the National Clean Air Programme (NCAP) introduced in January 2019, which targets PM2.5 reductions between 20-30% in 122 selected cities by 2024, with reference to a 2017 baseline. “Officials cite the pandemic as part of the reason for the programme’s slow implementation,” the report goes on to state.

Hindustan Times reached out to Sudhir Shrivastava, chairman of Maharashtra Pollution Control Board (MPCB), and VM Motghare, joint director of MPCB, for a comment but did not receive response till the time of going to press.