Toxicity! Delhi on a wing and a prayer

NEW DELHI: The impact of additional emissions due to firecrackers on Diwali is likely to stay in the air through most of the week due to calm wind conditions, with no respite from extremely toxic air likely until at least Friday, weather analysts said.According to the forecast by the Air Quality Early Warning System (AQEWS), further deterioration of air quality to the higher end of the 'very poor' category is expected by Diwali day, and to ‘severe’ levels by Tuesday.“The air quality is very likely to be in the ‘severe’ category from Tuesday till Wednesday — in case of enhanced emissions from firecrackers,” an AQEWS bulletin stated.

According to Commission for Air Quality Management, (CAQM), curbs under stage 1 of Grap were imposed on Oct 14.

Mahesh Palawat, vice president at Skymet Meteorology, said despite stubble burning not playing a key role yet, local emissions were accumulating due to stagnation. “For the last three to four days, we have seen calm winds at night, when the temperature is low. Even during the day, wind speeds haven’t exceeded 5-7 km/hr. This is not allowing pollutants to disperse, and we are seeing a slight haze during the day,” he said.

“In the next four to five days, we are not expecting any significant relief. Winds will not pick up, and the impact of firecrackers may linger for a few days,” Palawat warned.Delhi has had some form of ban on firecrackers since 2017, when the Supreme Court first asked the govt to halt sales to study the impact on air quality. In 2018 and 2019, limited use of green firecrackers was allowed, but police and local authorities struggled to distinguish between these and conventional crackers.

In the years that followed, even with a complete ban in place, the capital saw widespread violations, with pollution levels spiking sharply the day after Diwali.CPCB data shows PM 2.5 levels can spike between 20-30 times the permissible hourly limits across the city on Diwali day. When conditions are unfavourable, these emissions can take multiple days to disperse.Delhi's AQI has spiked the day after Diwali in nine of the last 10 years, barring 2022, when strong winds helped AQI improve the day after.Last year, Delhi’s AQI was 328 (very poor) on Diwali day (October 31), but spiked to 339 (very poor) the day after. In 2023, it went from 218 (poor) on Diwali day on November 12, to 358 (very poor) the day after. The last time Delhi’s AQI was 'severe' the day after Diwali was in 2021, when it shot up from 382 (very poor) on Diwali day on November 4 to 462 (severe) the day after.Out of the city’s 38 ambient air quality stations for which data was available on Sunday, Anand Vihar was already in the ‘severe’ zone with a reading of 430 at 4pm, while 23 other stations were in the ‘very poor’ range. These included Wazirpur (375), Vivek Vihar (355), Dilshad Garden (352), Jahangirpuri (341), Ashok Vihar (330), RK Puram (329) and Dwarka Sector-8 (323).