At “moderate", Bengaluru’s air is nowhere as bad as Delhi’s “severe", but its residents could feel the burning sensation of smoke in their throats on Monday. In most cities across the country, PM10 and PM2.5 readings rose further a day after Diwali due to the prevailing weather conditions and continued bursting of crackers despite all the anti-pollution campaigns.
While cities in the south and west, which have been receiving rain, still breathed reasonably clean air, in the capital, Delhi—among the world’s most polluted cities—the air quality index (AQI) rose sharply. This year, compared to 2018, air quality post Diwali has been marginally better in most cities due to the late onset of winter, but actionable plans need to be put in place if north Indian cities are to breathe easy.
“What Delhi needs is long-term systemic action to eliminate dirty industrial fuels, improve public transport and minimize waste burning and dust generation. Only then can there be a sustained impact. Otherwise, Delhi-NCR will plunge into a prolonged smog episode this winter too," said Anumita Roychowdhury, executive director-research and advocacy at the Centre for Science and Environment (CSE), New Delhi.
Delhi’s AQI, which is usually “very poor", stood at 506 the day after Diwali. On Tuesday, AQI read “severe", touching 740 in the Delhi University area, according to the ministry of earth sciences’ air quality monitor, SAFAR. “Severe" indicates that the air affects healthy people too and not just those with existing diseases.
In 2018, most cities and towns in northern India experienced “severe" pollution days (when AQI crosses 400) before Diwali, which was on November 7. This year, the delayed onset of winter and better wind speeds have dispersed pollutants to an extent, but the air quality is still very poor.
An analysis of Delhi’s air by CSE showed a ten-fold jump in PM2.5 concentrations between 5pm and 1am on Diwali, mainly due to bursting of firecrackers. PM2.5 is extremely hazardous as it not only affects the lungs, but can also enter the bloodstream. “This year, unlike 2018, the harsher winter conditions are yet to set in and the weather was relatively favourable. It was a warmer and windier Diwali," explained CSE’s Roychowdhury.
On the western coast, rain and wind brought by Cyclone Kyarr meant Mumbai enjoyed its cleanest Diwali air in the past five years, according to SAFAR. On Sunday, the day of Diwali, PM2.5 concentration was at 35, which falls in the “satisfactory" category. Post Diwali, PM2.5 concentration spiked to 48. As of Tuesday afternoon, PM2.5 concentration was at 53, still at the satisfactory level.
The SAFAR website explained that rain due to Cyclone Kyarr kept the city’s air quality at safe levels. “Although surface winds started to slow and temperature started to become cooler… moisture content in the atmosphere helped to keep pollution level in check. The sudden change in the monsoon dynamics worked positively to keep air quality in satisfactory range in spite of moderate fireworks," it said.
Heavy rain had been forecast for both Maharashtra and Goa over the festival weekend that cleared the air. “Secondly, people said there were fewer firecrackers compared to previous years, though this is purely anecdotal as of now. So, it is a combination of people acknowledging the problem and the meteorological conditions supporting it," said Aarti Khosla, director (climate trends) at Global Strategic Communications Council.
In Bengaluru, air quality, which is usually “good" or “satisfactory", crossed the 100-mark into “moderate" on Monday, causing breathing discomfort to those with respiratory and heart diseases, according to data from the Central Pollution Control Board of the environment ministry.
Madhusudhan Anand, co-founder of Bengaluru-based data startup Ambee, said urban air quality has been worsening since 2012.
“Growing traffic, construction and population density contribute to the air deteriorating." He said only a clear action plan can clean up the air across the country. “Particulate matter is generated by human activities—construction, garbage burning and urban pollution. Levels of gaseous pollutants like sulphur dioxide, sulphur oxide and nitrogen dioxide don’t drop hugely because of rain."
Bidya Sapam in Mumbai contributed to this story.