As winter sets in, city’s AQI set to worsen

Speaking to The Indian Express, Gufran Beig, founder of System of Air Quality and Weather Forecasting and Research (SAFAR), said, “In the coming days, as the temperature will start lowering, the AQI will remain between moderate to poor as the air quality will deteriorate.

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(Left) Fog blanket covers Mumbai early Saturday morning, as experts say the city’s AQI levels are slated to rise as temperatures dip further; (Right) civic workers clean the road at Kannamwar Nagar in Vikhroli, amid poor air quality. (Express File Photo)

As temperatures dip marking the onset of winter, the city’s air quality is starting to worsen with meteorologists warning of a further increase in the Air Quality Index (AQI) levels. On Saturday, the overall AQI touched 138, indicating a stark decline from Thursday when the city’s air quality monitoring stations registered an AQI in double digits.

On Friday, citizens woke up to a thick cover of smog as the IMD’s Santacruz observatory recorded a minimum temperature of 21.3 degrees Celsius. With the arrival of northerly winds, meteorologists told The Indian Express that Mumbai has started exhibiting conditions typically associated with winter season.

The minimum temperature dipped below 20 degrees Celsius for the first time this season on Thursday.

Even as the lower temperatures have brought respite from the heat and humidity that citizens have been reeling under since October, experts said the AQI levels are slated to escalate as the mercury levels dip further.

After recording good AQI days until Thursday owing to moderate showers which swept the city between November 24 and 26, the AQI in Mumbai declined to 138, with only two of the city’s 26 recording stations registering an AQI in double digits. In the city’s Navy Nagar pocket in Colaba, where the worst air quality was recorded, the AQI touched 235 followed by Shivaji Nagar in the eastern suburbs, wherein AQI of 214 was registered.

Speaking to The Indian Express, Gufran Beig, founder of System of Air Quality and Weather Forecasting and Research (SAFAR), said, “In the coming days, as the temperature will start lowering, the AQI will remain between moderate to poor as the air quality will deteriorate. However, it also depends on the behaviour of the surface winds which refers to the local winds.”

On the question of rising AQI during winters, Beig added, “When the temperature lowers, the inverse air, which is above ground and is like the upper lid of the atmosphere, comes down to approximately one kilometre and the pollution gets trapped within this small column. This results in the rise of the AQI. Secondly, when the temperature cools, it tries to slow down the dispersion of pollutants as the winds are slower.”

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Addressing the rise in the AQI levels over the past couple of days, Ronak Sutaria, founder of Respirer Living Sciences said, “In the last week of November, Mumbai experienced some unseasonal showers. Since the rain has cleared now, the AQI is rising. However, this isn’t the only cause of rise. Worsening air quality is a common winter phenomenon. During winters, the pollutants get trapped in the lower atmosphere which invariably leads to a rise in the AQI.”

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