"Even if 50% of the total load of toxic fire crackers as compared to Diwali past year is added, the prevailing weather conditions would aggravate the high smoke level and make air quality to persist in "severe" category for at least two days (8 and 9 November)", said the report. Experts have warned of severe spike in pollution levels after Diwali even if "partial toxic crackers" are burnt compared to a year ago. Last Diwali, Mumbai's AQI level was at 203 (poor).
As Diwali festivities picked pace on Wednesday and citizens began bursting firecrackers, the air quality in Mumbai worsened and entered the poor category.
While increasing air pollutants make it hard to breathe, pollution on Diwali would add to the woes of residents.
However, smoke from fireworks would get trapped, forcing levels of particles in the air to become significantly higher in the morning, taking air quality to the "severe" category.
The condition is expected to prevail till Diwali, however, it may improve if no additional emission from firecracker adds to the Delhi's air, said the System of Air Quality and Weather Forecasting and Research (SAFAR).
The average volume of PM2.5 and PM10, or particles with a diameter less than 2.5 and 10 microns, across 35 regions in Delhi was 368 and 507 microgrammes per cubic meters, which was 14 times higher than the limit. An AQI level between 0-50 is categorised as "good" while 51-100 is "satisfactory" and 101-200, 201-300 and 301-400 is in the "moderate", "poor" and "very poor" category respectively.
The pollution monitoring agencies said that the extra load of pollutants coming from stubble burning from neighbouring states also registered a slight drop, leading to slight improvement - though still in the danger zone.
PM10 concentration is expected to reach 575 and PM2.5 to 378 a day after Diwali, recording the worst air quality of the year, it said.
The Indian Institute of Tropical Meteorology also said that changes in the speed and direction of the wind, and more stubble burning, had made the air more toxic.
Meanwhile, the CPCB said it has recommended to the authorities that the entry of heavy vehicles in Delhi be banned after Diwali from November 8 to 10 when the air quality is expected to deteriorate further to "severe" level.
The level of PM2.5 pollutants in the air in South Delhi's Okhla area was 644, or 20 times the World Health Organization's declared safe level.