Pollution levels in Delhi remain ‘very poor’

Updated on Dec 02, 2022 09:19 AM IST

Delhi’s air quality on Friday was the worst compared to nine other cities monitored on the Central Pollution Control Board’s website

The average 24-hour AQI was 368 on Thursday. (Hindustan Times)
The average 24-hour AQI was 368 on Thursday. (Hindustan Times)

Pollution levels in Delhi remained in the “very poor” category on Friday morning with an hourly Air Quality Index (AQI) of 367 at 7am. The average 24-hour AQI was 368 on Thursday.

Delhi’s air quality on Friday was the worst compared to nine other cities monitored on the Central Pollution Control Board’s website.

On Thursday, the Union earth sciences ministry’s monitoring agency System of Air Quality and Weather Forecasting and Research said minimum temperatures have dropped gradually and caused fog during early morning hours, and were likely to lead to a deterioration in AQI.

“During afternoons AQI is mainly determined by local winds, maximum temperature/humidity and mixing layer height. Fine particles (size < 2.5 micrometer) contribute ~ 64% to PM10. Local surface winds being low (calm to 8 km/h) cause weak dispersion while [a] drop in minimum temperature (Max Temperature 27-26 deg C; Min 7 - 8 deg C) helps accumulation of pollutants.”

It said AQI is likely to be “very poor” for the next three days due to a low wind speed and inversion/stable conditions reducing the efficiency of dispersion and ventilation.

An AQI between zero and 50 is considered “good”, 51 and 100 “satisfactory”, 101 and 200 “moderate”, 201 and 300 “poor”, 301 and 400 “very poor”, and 401 and 500 “severe”. AQI in the “very poor” category can lead to respiratory illness on prolonged exposure.

The shallow fog was separately expected throughout Friday with a minimum temperature of around 8 degrees Celsius and a maximum of 25 degrees Celsius. On Thursday, the minimum temperature was 8.3 degrees Celsius, two notches below normal, and the maximum temperature of 25.4 degrees Celsius.

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