Delhi’s air quality ‘severe’ for second day

January 03, 2021 12:18 am | Updated 12:18 am IST - New Delhi

The air quality of Delhi and Noida continued to be in the ‘severe’ category for the second consecutive day on Saturday and Gurugram’s continued in the ‘very poor’ category, as per the Central Pollution Control Board.

The air quality of the Capital is expected to improve over the next three days. “The AQI will improve to the middle-end of the ‘very poor’ category by January 3; ‘poor’ category by January 4 and likely to further improve on the border or ‘poor’ to ‘moderate’ category by January 5,” said a statement by the government-run monitoring agency SAFAR (System of Air Quality and Weather Forecasting and Research).

The effect of stubble burning on the city’s air quality remained low on Saturday. But apart from pollutants, two meteorological factors strongly impact the air quality.

The “mixing layer height”, which is the height from the ground level up to which pollutants can be dispersed, was “low” on Saturday. This led to accumulation of pollutants near the surface.

Also, the speed of surface-level winds was “low”, which aided in accumulation of pollutants. Faster surface winds help in the dispersion of pollutants. The speed was predicted to pick up speed.

“The condition is likely to improve by Sunday as a fresh western disturbance is starting to effect the region, leading to relatively faster surface winds speed, better ventilation and moderate probability of rainfall. These meteorological combinations are likely to bring significant improvement to the current AQI condition in spite of colder temperature and relatively shallow boundary layer,” said monitoring agency SAFAR.

The AQI of Delhi was 443 on Saturday, slightly up from 441 on Friday, as per CPCB’s 4 p.m. bulletin.

The values for Gurugram and Noida were 336 and 448, respectively.

An AQI between 0 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”.

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