Air quality in the national capital is likely to improve on Friday with an increase in wind speed due to a fresh western disturbance and a dip in farm fires, the Ministry of Earth Sciences' air quality monitor SAFAR said on Wednesday.
It said Delhi's neighbouring states recorded only 480 incidents of stubble burning on Tuesday and the share of smoke from farm fires in Delhi's pollution is likely to decrease to 13 per cent on Thursday "in spite of favourable transport-level wind trajectory".
"A fresh western disturbance exists as a cyclonic circulation over Afghanistan and neighbourhood. It is likely to affect northwest India in the next two days, leading to an increase in the wind speed by Friday," SAFAR said.
On Wednesday, the air quality index is likely to deteriorate at night but will stay in the 'severe' category.
A reasonable improvement (to the 'very poor' category) is expected only by November 16, it said.
Delhi-NCR gasped for breath on Wednesday as the noxious smog resulting from raging farm fires and unfavourable weather pushed pollution levels in the region towards the "emergency" zone for the third time in the last 15 days.
A large number of children were exposed to the harmful levels of pollution as schools remained open.
The odd-even scheme also resumed on Wednesday after a two-day hold on restrictions in view of the 550th birth anniversary of Sikhism founder Guru Nanak Dev.
At 3.30 pm, Delhi's overall air quality index read 454. Rohini was the most-polluted area with an AQI of 486, followed by Nehru Nagar (484) and Jahangirpuri (483).
Faridabad (442), Ghaziabad (464), Greater Noida (460), Gurgaon (448) and Noida (468) also choked on extremely polluted air.
An AQI between 201 and 300 is considered 'poor', 301-400 'very poor' and 401-500 'severe'. An AQI above 500 falls in the 'severe plus' category.
According to weather experts, a fall in the temperature and wind speed led to the accumulation of pollutants. The problems were compounded by a cloud cover that blocked sunlight.
Incidents of stubble burning in Haryana and Punjab have increased and northwesterly winds have been bringing more farm fire plume to the Delhi-NCR region, they said.