The severe air pollution causing health emergency in Delhi that has grabbed international headlines may dissipate by Saturday-Sunday as favourable weather conditions are forecast that may cause a slow recovery in its air quality index (AQI).

The toxic haze covering Delhi’s skies is that for three weeks stagnant conditions caused by the delayed withdrawal of the monsoon had caused a deterioration due to accumulation of pollutants.

This impact is ending now, according to Safar India (System of Air Quality and Weather Forecasting And Research), under the Ministry of Earth Sciences and Indian Institute of Tropical Meteorology, Pune.

While AQI in Delhi is in the severe plus category, the highest grade of computation at 435, the US Embassy is denoting a sharp improvement in PM 2.5 levels compared to the peak values on Friday of 454.

On Saturday, the PM 2.5 count at 9 am has halved at 208, according to US Embassy data.

According to the forecast by Safar India, the overall air quality of Delhi continues to be in the severe plus. However, as the winds have become westerly from Saturday the further intrusion will be less and slow recovery is expected.

“The AQI is expected to remain in severe category today morning but likely to be recovering further by evening towards the upper end of very poor,” it said.

A fresh Western Disturbance is likely to advance to eastern regions of northwest India on Saturday, which is likely to positively influence Delhi’s air quality by increasing surface and boundary layer winds speed and thereby flushing out the accumulated pollutants.

“SAFAR extended outlook has warned 3 weeks back about the chance of high deterioration in AQI of Delhi during last week of October to the first week of November for prolonged periods mainly due to the delayed withdrawal of monsoon forcing stagnant conditions beneath to arrest any external intrusion for a longer period. This impact appears to be ending now, it said.

The worrisome part is that biomass burning in Punjab and Haryana hit a new peak with a contribution of 44 per cent in air pollution but that is expected to dissipate.

The effective stubble fire counts of Northwest India (Haryana and Punjab) touched a new peak value of this year (3,178) Friday.

The accumulation of pollutants sharply increased and stubble share in Delhi’s PM2.5 touched season’s high of 44 per cent on October 31 as against the expected 25 per cent. The share is predicted to drop down to 18 per cent by Saturday owing to an increase in ventilation index dispersing it.

“By November 3 significant improvement to the very poor is expected,” the forecast said.

The Environment Pollution (Prevention and Control) Authority had on Friday declared a public health emergency after air quality in the NCR region dipped to 410 on October 31.

Following the declaration, the Delhi government ordered the closure of all schools till November 5, banned construction activity and bursting of crackers during the winter season.

Meanwhile, the Arvind Kejriwal-led Delhi government has blamed Haryana and Punjab governments for Delhi’s deteriorating air quality. Kejriwal on Friday said that Delhi has turned into a “gas chamber” due to smoke from crop burning in the neighbouring states.