Delhi’s average air quality index for November was 377 – the worst in six years, data by the Central Pollution Control Board showed on Tuesday. Between 2015 and 2020, the average air quality index was 344.
An air quality index score between 301 and 400 is considered “very poor’’, as people can develop respiratory illnesses if they have prolonged exposure to the pollution.
Delhi and its neighbouring areas have been grappling with poor air quality since Diwali. The air pollution has resulted in restrictions on traffic movement and construction activities and shutting down of schools in the national Capital.
In November, Delhi recorded 11 days when the air quality index ranged between 401 and 500, which falls under the “severe” category. Last year, the national Capital had witnessed nine such days, while in 2018, there were five days of “severe” air quality.
In October this year, Delhi did not witness a single day of “very poor” or “severe” air quality, the data showed.
Gufran Beig, founder project director of weather forecasting agency Safar, said that the air in October was cleaner as stubble burning by farmers was postponed because of delayed monsoon withdrawal, The Indian Express reported.
“Usually, the air quality gets bad in October and November, but this year, the worst was shifted to November,” he said.
Farmers burning stubble in neighbouring states is also considered a factor for rise in Delhi’s air pollution, but the Centre had told the Supreme Court last month that burning of farm waste accounted for just 10% of the emissions on an average throughout the year.
However, Safar’s accessed by The Indian Express on Wednesday pointed at the alarming contribution of stubble burning at the beginning of November. The share of stubble burning to Delhi’s pollution on November 7 was 48%. It decreased to 3% by the end of November.
The deteriorating pollution situation could also be blamed on the fall in temperature and low wind speed. On sunny days, the warm air rises from the ground and disperses the pollutants. When the temperature decreases in winters, the air does not rise, trapping the pollution closer to the ground.