Danger to step out, air at season's worst

New Delhi: A layer of eye-stinging smog lingering over Delhi-NCR thickened on Friday, giving an orange tint to the sun and lowering visibility to 200 metres at several places in the region as the Capital breathed the worst air this season so far with an air quality index recorded at 471 - on the brink of emergency levels.
Authorities on Friday advised people to limit outdoor activities and told government and private offices to cut vehicle use by at least 30 per cent amid the rise in emissions from farm fires and unfavourable meteorological conditions resulting in toxic air in the city.
Over 4,000 farm fires, accounting for 35 per cent of Delhi's pollution on Friday, played a major role in pushing the 24-hour average Air Quality Index (AQI) to 471 by 4 pm, the worst this season so far.
Gufran Beig, the founder project director of SAFAR, said stubble burning generally contributes to PM2.5 but this time its coarser particles in PM10 are also becoming a lead pollutant at several locations in Delhi.
"This is a new feature in the winter. This is mainly because of the particle growth mechanism due to high humidity at night and increased humidity during the day probably due to water sprinkling which increases the holding capacity of the air. Since the flow is regular, many PM2.5 particles are growing towards PM10 (sic)," he said.
According to SAFAR, stubble burning has accounted for at least 25 per cent of Delhi's PM2.5 pollution for nine days on the trot, starting November 4.
A sub-committee on Graded Response Action Plan (GRAP) said meteorological conditions will be highly unfavourable for dispersion of pollutants till November 18 and agencies concerned must be fully ready to implement measures under 'emergency' category.
The measures to be followed in the 'emergency' situation include stopping the entry of trucks in Delhi, ban on construction activities and introducing the odd-even car rationing scheme.
The Central Pollution Control Board (CPCB) said the 24-hour average concentration of lung-damaging fine particles known as PM2.5 in Delhi-NCR crossed the 300 mark around midnight and stood at 381 micrograms per cubic metre at 4 pm on Friday, over six times the safe limit of 60 micrograms per cubic metre.
The PM10 level was recorded at 577 micrograms per cubic metre, over five times the safe limit of 100 micrograms per cubic metre.
According to an analysis by the Delhi Pollution Control Committee, people in Delhi breathe the worst air between November 1 and November 15 every year. The city has recorded severe air quality on six of the last eight days after Diwali. Faridabad (460), Ghaziabad (486), Greater Noida (478), Gurgaon (448) and Noida (488) also recorded severe air quality at 4 pm on Friday.
India Meteorological Department officials said moderate fog and low temperatures in the morning — a low of 12.6 degrees Celsius on Friday — and calm winds have been trapping pollutants close to the ground.
"Visibility levels at the Indira Gandhi International Airport and the Safdarjung Airport dropped to 200-500 metres due to moderate fog. It intensified on Friday due to high humidity," an official said.