Air Quality Index witnesses sharp spike in Mumbai, is highest since before lockdown began in March

The city recorded its worst air quality on Friday since before the Covid-19 lockdown was enforced in March. Reduction in rain activity and increase in emission sources

The city recorded its worst air quality on Friday since before the Covid-19 lockdown was enforced in March. Reduction in rain activity and increase in emission sources owing to lifting of restrictions pushed up the pollutant-measuring indicator — air quality index (AQI) — to 118 (moderate) for PM2.5 (small pollutant particles that can easily enter the lungs and cause health ailments), as a thin layer of smog engulfed Mumbai’s skyline.

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According to the System of Air Quality Weather Forecasting and Research (SAFAR), it is the first time since March 19 that Mumbai’s AQI entered the ‘moderate’ category (101-200). It was 130 on March 19, after which till Friday, it had stayed below 101.

SAFAR categorises 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’.

The AQI on Monday was 50, which rose to 68 on Tuesday, 78 on Wednesday and 97 on Thursday before entering the moderate category on Friday.

“This was expected as when conditions become favourable for monsoon withdrawal, there is a sharp drop in wind speed and rise in temperature, especially for a coastal city like Mumbai. This allows pollutant particles to get suspended close to the surface and form a layer of haze,” said Gufran Beig, project director, SAFAR. “Pollution levels are likely to be in the moderate category for at least two to three days. But with a low pressure weather system over Bay of Bengal, the possibility of rain even around the Mumbai region could allow a marginal rise in wind speed.”

An AQI of 104 (moderate) has been predicted for Saturday.

Friday’s AQI, however, was an average from nine locations and not 10 as the AQ monitoring station at Bandra-Kurla Complex (BKC) is under maintenance, said Beig. The highest pollution level was recorded at Navi Mumbai –186 (moderate), followed by Andheri 156 (moderate); Malad 152 (moderate); Chembur 149 (moderate); Worli 128 (moderate), while remaining areas recorded ‘satisfactory’ AQI levels.

Meanwhile, the maximum temperature on Friday in Mumbai was 35 degrees Celsius at the Santacruz weather observatory and 34.6 degrees Celsius at Colaba, both 2.3 degrees Celsius above normal. The India Meteorological Department (IMD) has predicted a yellow alert for the next five days for Thane and other districts in south Konkan. However, only light rain has been predicted for the city and suburbs over the next five days.