Delhi: December’s first severe air episode likely from Friday

NEW DELHI: The capital’s air quality, currently in “very poor” category, may see “severe” days between December 4 and 7 due to meteorological factors. In November, Delhi had recorded nine “severe” air days.
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On Tuesday, the city’s air quality index (AQI) was 367. “The air quality is very likely to remain in upper end of ‘very poor’ category owing to unfavourable meteorological conditions for dispersal of pollutants in the next five days.There is a possibility of air quality reaching in ‘severe’ category between December 4 and 7,” said Air Quality Early Warning System for Delhi, a body under the Union ministry of earth sciences.
V K Soni, head of Environment Monitoring and Research Centre at India Meteorological Department, said, “A western disturbance is approaching on December 4 and it is predicted that winds may become slow, leading to accumulation of pollutants.”
Delhi’s air quality may deteriorate in “very poor” category on Wednesday and is predicted to show slight improvement on Thursday but within the same category.
Kuldeep Srivastava, scientist at IMD and head of Regional Weather Forecasting Centre, said, “An average wind speed of 7kmph was recorded on Tuesday and due to slow wind speed, the dispersion of pollutants was affected. The minimum temperature of 8.1 degrees Celsius, two notches below normal, was recorded on Tuesday and low temperature slows down the dispersal of pollutants.”
Srivastava said wind direction was predicted to shift from north-westerly to easterly on Friday. “During the transition phase of change in the wind direction, pollutants are likely to get trapped causing further deteriorating in air quality. Calm winds are predicted to prevail over the region after two-three days,” he said.
System of Air Quality and Weather Forecasting and Research (SAFAR), a central forecasting body, said boundary layer wind direction is north-northwesterly and partly favourable for stubble fire-related transport. The number of fire counts observed in neighbouring states were 258 while its share in Delhi’s PM2.5 was 4% on Tuesday.
“Air quality is likely to worsen in north India due to low temperatures along with calm winds and near-surface inversion. Surface-level winds are calm. Ventilation conditions are likely to slow down,” SAFAR forecast.