Air quality in Mumbai improves after a week

Seabird sailboats off Gateway of India on Sunday when the city’s overall AQI stood at 197. Pic/Shadab Khan

After ‘poor' and ‘very poor' air all of last week, Mumbai's pollution levels seemed to have dropped with an increase in wind speed. The air quality index on Monday stood at 139 (moderate).

The System of Air Quality Weather Forecasting And Research (SAFAR) recorded an AQI of 139 (satisfactory) for the city - a drop from 309, 286 and 197, recorded on Thursday, Friday and Saturday, respectively. As per the forecast issued by SAFAR, the AQI for the overall city will improve further from Tuesday.

Mazgaon and Chembur, the only stations which recorded an AQI value of 201 and 249, were the most polluted in the city on Monday.

Meanwhile, the city is witnessing a sudden increase in the maximum temperature, which touched 35.6 degrees celsius on Friday and 35.9 and 35.2 degrees celsius on Saturday and Sunday, respectively, as per data from the India Meteorological Department.

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The maximum temperature recorded at IMD's Santacruz observatory on Monday was 33.5 degrees celsius, whereas the Colaba observatory recorded a maximum temperature of 33.2 degrees celsius.

An AQI between 100 and 199 is considered ‘moderate', 50 and 99 ‘satisfactory' and below 50 ‘good'. An AQI over 200 is considered ‘poor', above 300 ‘very poor', above 400 ‘severe' and above 500 ‘severe+'. In 2020-21, the share of good air quality days was 32 per cent while no ‘very poor' or ‘severe' air quality days were recorded across the state.

Mumbai had on last Monday (December 12) recorded an overall AQI of 225 which falls in the ‘poor' category, compared to Delhi which recorded a ‘moderate' AQI of 152. On Tuesday, (December 13) overall AQI of the city was 204.

Gufran Beig, founder and project director of SAFAR, said, "Increased wind speed has led to improved AQI in Mumbai in the past few days. This is a reversible effect. When the wind was stagnant in Mumbai during the first two weeks of December, the AQI was poor or very poor. While in Delhi it was better than in Mumbai. Now the wind is stagnant there in the northern parts of the country, while here the wind circulation is faster and the temperature is warmer, leading to better AQI. This effect is very unusual for this time of the year and it will continue for a few days."

"Mumbai is surrounded by sea on three sides, so surface wind speed is normally higher. There is also wind reversal now and then. When winds originate from the oceanic side, it is clean and it sweeps away all the city's pollution leading to cleaner AQI but when it gets reversed, AQI deteriorates," Beig added.

AQI on Monday

Bhandup: 121 (moderate)
Colaba: 102 (moderate)
Malad: 162 (moderate)
Mazgaon: 201 (poor)
Worli: 98 (satisfactory)
Borivli: 96 (satisfactory)
BKC: 135 (moderate)
Chembur: 249 (poor)
Andheri: 166 (moderate)
Mumbai (overall): 139 (moderate)