Twenty of 26 air quality monitoring stations across the country recorded “severe” air quality at midnight on Wednesday night, a level of pollution that India officially rates as its worst possible, and describes as one that “affects even healthy people, and seriously impacts those with existing diseases”. In Delhi, particulate matter levels surpassed the worst that Beijing has experienced, The Hindu’s analysis of air quality data shows.
On Wednesday night, which was Diwali night, air quality deteriorated across the eight states for which data is available through the Central Pollution Control Board’s National Air Quality Index monitoring portal. Looking at PM2.5 levels - the hourly concentration of very fine particles up to 2.5 microgrammes in diameter which can severely affect respiratory functioning - alone, The Hindu found that even cities with relatively better air quality saw a dip on Wednesday night. Both the System of Air Quality and Weather Forecasting And Research at the Indian Institute of Tropical Meteorology, Pune, and the Centre for Science and Environment in Delhi confirmed that firecrackers had contributed to the worse air quality.
In Chennai, the air quality reached “severe” or “very poor” levels on Tuesday night, when Diwali is celebrated in that city, and improved on Wednesday night. In most of the rest of the country, PM2.5 levels were at “severe” levels on Wednesday night. In Dwarka (Delhi), the PM2.5 levels were “very poor”, while at the BWSSB-Kadabesanahalli monitoring station in Bengaluru, the index was at “poor”. The Airoli monitoring station in Navi Mumbai was the only one which recorded “satisfactory” levels of PM2.5 throughout the period.
In Delhi, hourly concentrations of PM2.5 available from the Delhi Pollution Control Committee showed that levels spiked to 985 microgrammes per cubic metre at 9.20 pm on Wednesday night in RK Puram, as against the World Health Organisation’s safe standard of 60. This was twice as high as the PM2.5 levels earlier this month in Singapore which forced school closures and the relocation of outdoor and sporting events. It was higher than the worst levels experienced by Beijing this year, and just a little lower than the worst PM2.5 levels ever recorded in China, which was last week in Shenyang, northeast China (1157 microgrammes per cubic metre). Moreover, the air Indians actually breathe may be even worse. The Centre for Science and Environment’s exposure monitoring at various locations in Delhi on Wednesday night - using handheld monitors to measure the actual air quality residents are breathing as opposed to the ambient air quality recorded by official monitors - revealed even higher PM2.5 levels of up to 2500 microgramme per cubic metre, or 40 times the safe standard. Old Delhi and Laxmi Nagar in East Delhi were the worst affected.
| AQI level | Remark | Color Code | Possible Health Impacts |
|---|---|---|---|
| 0-50 | Good | Minimal impact | |
| 51-100 | Satisfactory | Minor breathing discomfort to sensitive people | |
| 101-200 | Moderate | Breathing discomfort to the people with lungs, asthma and heart diseases | |
| 201-300 | Poor | Breathing discomfort to most people on prolonged exposure | |
| 301-400 | Very Poor | Respiratory illness on prolonged exposure | |
| 401-500 | Severe | Affects healthy people and seriously impacts those with existing diseases |
“Air pollution hotspots are starting to spread across the country. Delhi gets all the focus, but there are other cities with worse air quality,” Anumita Roychowdhury, executive director, CSE, said. Moreover, the adverse health impact of poor air quality begins from far lower levels of pollution than those experienced in Delhi, she said. “We need a clean air action plan on a countrywide basis. But it is also important that state government should come up with implementation strategies to inform people to take precautions - staying indoors on “severe” days, or asking children not to play outside,” she said. There should also be a pollution emergency action plan as followed by other countries, when vehicles are taken off the streets and industrial units shut down on emergency days, she added,
