Farm fires cause 'severe' air again

Stubble smoke accounted for 37.5% of PM2.5 on Friday, a season-high, the Decision Support System stated

- Jasjeev Gandhiok

Increased smoke from stubble burning and unfavourable meteorological conditions over the Capital on Friday and Saturday led to the deterioration of the air quality index to the "severe" category, as pollutants accumulated over the region and winds slowed down. Stubble smoke accounted for 37.51% of Delhi PM2.5 (particulate matter with a diameter of 2.5 microns or less) concentration on Friday, a season-high, according to the Centre's Decision Support System (DSS).

Delhi recorded a 24-hour average air quality index (AQI) of 417 ("severe") at 4pm on Saturday, according to the Central Pollution Control Board's (CPCB's) daily bulletin. It was 396 ("very poor") a day before.

Winds, which had become favourable for the dispersion of pollutants, picked up to 14km/hr during the day on Friday before slowing down towards late evening, predominantly remaining calm. Delhi witnessed a dip in the minimum temperature, to 15.3°C on Saturday from 15.6°C recorded a day before, and instances of firecrackers being burst across the city on Friday night were also reported.

"Meteorological conditions were expected to be favourable on Saturday, increasing to 15km/hr during the day, but winds remained slow. The maximum wind speed was 8km/hr, but it mostly remained calm. We expect winds could pick up to 15km/hr on Sunday, which could again help improve the AQI," said Mahesh Palawat, vice president at Skymet meteorology.