Despite good weather, air stays 'very poor'

New Delhi: The national capital suffered from 'very-poor' air quality on Sunday afternoon despite good winds and favourable weather.

While most of the regions across Delhi recorded air quality in the 'very poor' or 'poor' category, some areas were well 'above severe' and 'severe' levels.

The major pollutant PM2.5 or particles with diameter less than 2.5 mm were four times at Anand Vihar in east Delhi, Mundaka in west Delhi and Wazirpur in north east Delhi.

The Air Quality Index of Delhi at 1 p.m. was 299 according to Central Pollution Control Board, considered 'poor', however, System of Air Quality and Weather Forecasting And Research (SAFAR) recorded Delhi air under 'very poor' category.

The air quality remained bad even as Delhi saw low humidity (40 per cent) at 11 a.m. against 90 per cent at 5.30 a.m. Low humidity along with winds disperse pollutants suspended in the air, thereby improving air quality.

"Delhi received north-westerly winds in the morning at good speed but at 1 p.m. the wind speed changed to easterly. Wind speed is good so it must help in improving the air quality or at least avoid it from getting worse," an India Meteorological Department (IMD) official said.

The dry and cold north-westerly winds also bring smoke from stubble burning to Delhi.

According to NASA satellite images, stubble burning activities have been stepped up in neighbouring Punjab and Haryana, with a few cases of burning in Delhi as well, over the past 24 hours.

At 2 p.m. the average concentration of PM2.5 across Delhi was 154 microgram per cubic metre.

The safe limit for PM2.5 is 25 units as per international standards and 60 units as per national standards.

SAFAR has issued an advisory cautioning people in Delhi to avoid outdoor physical exercises.