The air quality of Delhi and Noida deteriorated to the “severe” category and that of Gurugram’s to the “very poor” category on Tuesday, according to the Central Pollution Control Board (CPCB) data. The national capital’s air quality is expected to improve in the coming days.
“The ventilation coefficients are likely to improve significantly from tomorrow and AQI is likely to improve to the middle to lower end of very poor on January 20. The AQI is forecast to further improve to the lower end of the ‘very poor’ to ‘poor’ category on January 21. Marginal deterioration of AQI to ‘very poor’ category is forecast on January 22,” 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 Tuesday. Also, the speed of surface-level winds was “moderate”, which aided lesser accumulation of pollutants near the surface.
But the “mixing layer height”, which is the height from the ground level up to which pollutants can be dispersed, was “low”. This also led to accumulation of pollutants near the surface.
The AQI of Delhi was 404 on Tuesday, up from 372 on Monday, as per CPCB’s 4 p.m. bulletin, which is an average of the past 24 hours. The values for Gurugram and Noida were 366 and 432 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”.
