E-Paper
Mumbai witnesses its cleanest air day since monitoring began in city
Tuesday’s AQI equalled the all-time improved air quality over the past five years, which was recorded on September 4, 2019, at 12.
Overnight rain and high speed winds helped Mumbai record its lowest air pollution levels on Tuesday since air quality monitoring began in 2015, It has equalled the all-time low air quality recorded on September 4, 2019.
The pollutant-measuring indicator -- air quality index (AQI) for PM2.5 pollutant, the breathable particulate matter that is 2.5 microns in size or smaller, which can cause health hazards, as they can be easily inhaled -- was 12, or in the “good” category, according to the System of Air Quality Weather Forecasting and Research.
The AQI forecast for Wednesday is at 10 and is likely to be the best since the monitoring started in 2015.
Tuesday’s AQI equalled the all-time improved air quality over the past five years, which was recorded on September 4, 2019, at 12.
On Tuesday, Mumbai’s air was cleaner than major international cities such as London (21), Tokyo (52), Sydney (25), and Singapore (25).
However, New York’s AQI topped Mumbai’s at 10.
Researchers from the System of Air Quality and Weather Forecasting And Research (SAFAR), under the Union Ministry of Earth Sciences, said a combination of factors had led to improved air quality in Mumbai.
“The coronavirus disease (Covid-19)-induced lockdown restrictions had brought down the PM concentration to its background levels because of lack of human-induced emissions of greenhouse gases. It takes time for PM levels to rise again even after emissions resurface. Intense rainfall over Mumbai between Monday night and early Tuesday morning, the high moisture content in the city’s air, combined with wind speed ranging at a maximum of 30 kilometres per hour (kmph) allowed swift dispersion of pollutants close to the surface,” said Gufran Beig, director, SAFAR.
“This is a characteristic of the monsoon season but it is getting further enhanced due to lockdown restrictions that are in place since mid-March. AQI and PM concentration is likely to remain in the ‘good’ category, as more rains are predicted over the city in the coming days,” he added.
The concentration of PM2.5 was as low as 7 micrograms per cubic metre (µg/m3) against the prescribed limit of 60µg/m3 for 24 hours is considered a national safety standard and 25 µg/m3 as the World Health Organization (WHO) safety standard. PM2.5 levels are likely to fall further to 6 µg/m3 on Wednesday and 10 µg/m3 on Thursday, said SAFAR authorities.
PM10 (large coarse particulate matter of 10-micron size or smaller) was 14 µg/m3 against the safety limit of 60 µg/m3. It is expected to be 11 µg/m3 on Wednesday and 16 µg/m3 on Thursday.
SAFAR authorities categorise AQI levels for PM2.5 in the 0-50 range as good; 51-100 as satisfactory; 101-200 as moderate; 201-300 as poor; 301-400 as very poor and above 400 as severe.
All 10 locations, where AQI was monitored in the city, recorded “good” air quality and it didn’t cross 30.
Colaba had the cleanest air with an AQI of 2, followed by Mazgaon (5), Bhandup and Chembur (8), Borivli (10), BKC (15), Andheri (16), Malad (17), Worli (18), and Navi Mumbai (26), the highest.
