Air quality in Mumbai improves to ‘satisfactory’ after days of ‘poor’ airUpdated: Jan 28, 2020 17:34 IST
Two days after the city recorded its highest pollution levels for the month, the pollutant-measuring indicator, air quality index (AQI), dropped to ‘satisfactory’ levels on Tuesday.
The AQI for PM2.5 — particulate matter of 2.5-micron size that can easily enter the lungs and cause ailments — which was 265 (poor) on Sunday, improved to 178 (moderate) on Monday, and to 88 (satisfactory) on Tuesday, according to the System of Air Quality Weather Forecasting and Research (SAFAR).
The concentration of PM2.5 and PM10 (larger coarser particles) were at safe levels. PM2.5 concentration in Mumbai’s air was 49 microgrammes per cubic metre (µg/m3) against the daily safe limit of 60 µg/m3, and concentration for PM10 (larger coarser particles) was 84 µg/m3 against the safe limit of 100 µg/m3.
On Sunday, the concentration was 123 µg/m3 for PM2.5 and 192 µg/m3 for PM10. Researchers said air quality improved due to changing weather factors.
“A considerable rise in wind speed was witnessed over Mumbai from Tuesday morning onwards that helped disperse the pollutant boundary layer close to the surface. Marginally high day temperature is further assisting reduction in air pollution. This air quality will continue for at least four to five days until any other significant weather changes take place,” said Gufran Beig, project director, SAFAR, which categorises AQI for pollutants 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.
Of the 10 locations in Mumbai where SAFAR monitors air quality, seven areas recorded ‘satisfactory’ air with best air quality at Colaba and Bhandup at 53. Navi Mumbai was the most polluted location with an AQI of 156, followed by Malad (144) and BKC (119).
Meanwhile, the city witnessed cloud cover during the early hours of the day followed by a clear sky in the afternoon.
A marginal drop in minimum temperatures was witnessed as the suburbs recorded 19.2 degrees Celsius while 20 degrees Celsius was recorded in south Mumbai, both still above the normal mark. The weather bureau has predicted a drop in both minimum and maximum temperatures for Wednesday till Friday owing to cool northerly winds over Mumbai.
Independent experts said the AQI has been dependent on the maximum temperature.
“A reduction in maximum temperatures [compared to the last week] is leading to a decline in the AQI. In addition, the wind speed went up on Tuesday and the region is now witnessing winds from the west to the northwest. Significant deterioration of the AQI is unlikely in the remaining days of this month due to increased wind speed along with reduced maximum temperatures and moisture. The AQI might start deteriorating in early February since temperatures and moisture are expected to go up,” said Akshay Deoras, meteorologist and PhD researcher department of meteorology, University of Reading, UK.
Mumbai Metropolitan Region (MMR) witnessed cloudy weather conditions on Tuesday. “A western disturbance [winter weather system] is active in north India and its presence has resulted in the formation of a trough [elongated low-pressure] near the surface across northwest India, Gujarat and the Arabian Sea. This led to the formation of low clouds over the MMR. Mumbai’s Doppler radar indicated light drizzle in some parts during the early morning hours of Tuesday,” said Deoras.