Experts said air quality was likely to deteriorate gradually over the next few days. "However, Delhi is unlikely to see severe air quality in November," said DipankarSaha, who heads CPCB's air laboratory.

The average PM2.5 level, according to System of Air Quality and Weather Forecasting and Research (SAFAR), was 146 micrograms per cubic metre — a slight drop from Monday's 154. Similarly, PM10 was recorded at 235 as compared to 243 on Monday. SAFAR's forecast shows these levels to be rising gradually over the next three days.

With the air again turning more toxic, Delhi environment minister Imran Hussain directed environment secretary Keshav Chandra to continue measures like spraying of water and mechanised sweeping in the next few weeks. He also listed additional measures, including providing non-biomass heating facilities to guards and at night shelters to prevent open burning and stopping use of firecrackers.

The minister also told the agencies to remove any waste collecting on the ground and impound polluting vehicles.