Mumbai’s air quality dips to ‘moderate’ as dust pollution increases

After four-and-a-half months of ‘good’ or ‘satisfactory’ air quality, the city recorded ‘moderate’ pollution levels on Wednesday.

After four-and-a-half months of ‘good’ or ‘satisfactory’ air quality, the city recorded ‘moderate’ pollution levels on Wednesday.

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Researchers from the System of Air Quality Weather Forecasting and Research (SAFAR) said there was a spike in dust pollution as the air quality index (AQI) was recorded at 111.

SAFAR 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.

Bhandup was the most polluted location in the city with an AQI of 307 (very poor) owing to an increase in location specific emissions, said SAFAR officials. Only Worli, Mazgaon and Colaba recorded ‘good’ air quality on Wednesday while remaining areas recorded ‘moderate’ AQI levels.

The AQI for PM10 (larger coarser particulate matter that suspends in the air for longer and predominantly forms due to windblown dust) was 111 (moderate) while the AQI for PM2.5 (smaller particles of 2.5 micron size that can easily enter the lungs and cause ailments) was 106 (also moderate). Against the safe limit of 100 micrograms per cubic metre (µg/m3), the concentration of PM10 was 130µg/m3 on Wednesday, which is likely to rise to 131µg/m3 on Thursday, and 141µg/m3 on Friday. The concentration of PM2.5 was within the safe limit on Wednesday.

“After monsoon withdrawal over Mumbai, a drop in rain activity has kept larger pollutant particles, daily generated by the city, floating in the air. With high moisture, humidity and temperatures, these particles suspend closer to the surface, creating a layer of dust. This increases overall air pollution,” said Gufran Beig, project director, SAFAR.

According to a source apportionment study for PM10 in Mumbai by researchers from UrbanEmissions.info, dust emissions account for 50% of all emissions. This is followed by 28% industrial emissions; 11% from the transport sector, and 3% each from waste burning, diesel generator sets, and brick kilns. Residential emissions account for 2%.

The percentage share of fine particulate toxic particles (annual average) that make up particulate matter was highest in Mumbai in 2018 as compared to Ahmedabad, Pune, and Delhi, according to SAFAR.

Pollution levels are likely to remain in the ‘moderate’ category on Thursday as an AQI 109 has been predicted.