After Cyclone Ockhi, Mumbai breathes cleanest December air | mumbai news | Hindustan Times
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After Cyclone Ockhi, Mumbai breathes cleanest December air

The AQI level on Wednesday fell under the ‘good’ category, making it the cleanest air day in December since air quality monitoring began in Mumbai in 2015

mumbai Updated: Dec 07, 2017 10:37 IST
Badri Chatterjee
Researchers attributed the drop in pollution levels to high wind speed over the city because of cyclone Ockhi that passed west of Mumbai on Tuesday.
Researchers attributed the drop in pollution levels to high wind speed over the city because of cyclone Ockhi that passed west of Mumbai on Tuesday.(Pratik Chorge/HT)

Cyclone Ockhi led to a significant drop in pollution levels in the city on Wednesday.

After a week of ‘moderate’ air quality, the pollutant measuring indicator — air quality index (AQI) — fell to 43. AQI for particulate matter (PM2.5) pollutant — small-sized pollutants that can easily enter the lungs and cause health hazards — was 41, while PM10 (coarse particles that of 10 micron size) was 43.

An AQI level between 0-50 is good, 51-100 is satisfactory, 101-200 is moderate, 201-300 is poor.

The AQI level on Wednesday fell under the ‘good’ category, making it the cleanest air day in December since air quality monitoring began in Mumbai in 2015. A similar AQI of 49 (good) has been predicted for the city for Thursday.

The cleanest air day this year and since air monitoring began in Mumbai was recorded on October 12, when the AQI was 32 (good).

Researchers attributed the drop in pollution levels to high wind speed over the city because of cyclone Ockhi that passed west of Mumbai on Tuesday. “The cyclone has come as a blessing for Mumbai as it has paved way for clean air. While Mumbai has the advantage of sea breeze, air quality improving to this level during December is an unusual event,” said Gufran Beig, project director, SAFAR. “Pollution levels were in the ‘poor’ category almost a week back. High speed winds over the past few days did not allow the pollutants to settle close to the surface, and rain on Tuesday completely washed them away.”

He said Mumbai can expect clean air until Saturday and pollution levels are expected to rise thereafter as temperatures increase and wind speed reduces.

HT had reported, on September 8, that Mumbai’s air was more toxic than Delhi in November and December last year because it had a higher concentration of hazardous particulate matter (PM) than the Capital. The concentration of PM1 (smaller than one micrometre and the most dangerous pollutant) was 45 microgram per cubic metre (µg/m3) in Mumbai in December 2016, against 42µg/m3 in Delhi, found the System of Air Quality Weather Forecasting and Research (SAFAR).

On Wednesday, Chembur had the cleanest air in the city with AQI levels for PM2.5 at 22, while Navi Mumbai had the most polluted air with an AQI of 71. All 10 locations in Mumbai either recorded ‘good’ or ‘satisfactory’ air quality.

The concentration of particulate matter was well below the safe limit prescribed by the Central Pollution Control Board. As against a safe limit of 60 microgrammes per cubic metre (µg/m3) for PM2.5 for 24 hours, Mumbai recorded 25µg/m3 and 41µg/m3 for PM10 as against safe limit of 100µg/m3 for 24 hours.

Read more:
Cyclone Ockhi passes, Mumbai wakes up to dry weather