Delhi’s air quality very poor, mercury likely to dip to 9 degrees Celsius

According to the Central Pollution Control Board, the hourly air quality index (AQI) in the national capital was 319 at 7am

Delhi’s air quality was in the very poor category on Monday morning with a minimum temperature expected to be 9 degrees Celsius and a maximum of 27 degrees Celsius. According to the Central Pollution Control Board, the hourly air quality index (AQI) was 319 at 7am. On Sunday, the average 24-hour AQI was 314.

On Sunday, the average 24-hour AQI was 314. (ANI)

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’.

On Monday, the government’s monitoring agency System of Air Quality and Weather Forecasting and Research said pollutants emitted from stubble burning contributed 10% to PM2.5 and fine particles (size < 2.5 micrometer) ~ 57% to PM10. “Local surface winds being low (6 km/h) cause weak dispersion while [a] drop in minimum temperature...also helps accumulation of pollutants. Moderate ‘Mixing layer height’ during daytime (~ 1.0 – 1.5 km) enhances vertical mixing.”

AQI was likely to remain within the lower end of very poor on Monday. “For the next 3 days, upper-level winds are from [the] northwest direction that is likely to increase transport of pollutants from stubble burning region if fire counts increase. AQI is likely to be within ‘Poor’ or ‘lower end of very poor’ for the next 3 days due to [a] net effect of inflow of pollutants and local dispersion and ventilation,” the agency said.

On Sunday, the minimum temperature was 9.6 degrees Celsius, three notches below normal, and the maximum of 26.8 degrees Celsius, a degree below normal.