NEW DELHI :
The quality of air worsened in Delhi on Monday, a day after Diwali, but pollution trackers and city authorities blamed a spike in post-harvest stubble burning as they warned residents with respiratory problems not to step out.
The air quality index (AQI) breached the “severe" mark at 506, the season’s worst so far, according to the Centre-run System of Air Quality Forecasting and Research (SAFAR).
While the 24-hour AQI average for Delhi was identified at 368, the real-time AQI figure after 12pm on Monday stood at 506.
“The overall air quality of Delhi is in the ‘severe’ category today as forecast. Though the PM2.5 concentrations peaked around midnight (1am), the concentrations were much less than that of the last three years," said a SAFAR assessment report on Monday evening.
While the heavy smog that hung over the city after the Diwali festival in the past two years was absent, pollution levels that earned Delhi the moniker of the world’s most polluted city were still much above the safe level for its residents.
PM2.5—fine particulate matter in the air that are two and one half microns or less in width—was at the 500+ level and PM10 pollutants stood at 446. Both breached the “severe" mark on the index, prompting municipal corporation authorities in the city to order roads sprinkled with water in several localities.
SAFAR’s early assessment had shown that the air quality after Diwali may not be as bad as that of last year and will likely remain severe for a shorter period as compared to that in 2018. But it also said “the impact of stubble burning incidents is also expected to rise over the next few days, as wind direction changes. The fire count has almost doubled in the past two days, but surface winds prevented accumulation of particulate matter".
In worse news, especially for those with respiratory illnesses, the report added that “the first week of November is likely to be the worst in terms of air quality, when lack of winds will likely prevent dispersion of air pollutants leading to a spike in pollution".
PM2.5 are smaller size pollutants that are extremely harmful as they can enter the bloodstream, unlike PM10, which impact the lungs.
Delhi chief minister Arvind Kejriwal said on Monday that the post-Diwali pollution level in the national capital was the lowest in five years.
An advisory was issued on SAFAR, asking people to avoid outdoor physical activity. People with heart and respiratory diseases have been asked to remain indoors.
As per the SAFAR forecast, the situation on Tuesday will see only a marginal improvement, with AQI seen “very poor" at 345, and PM2.5 and PM10 levels estimated at 345 and 195, respectively.
Srishti Choudhary contributed to this story.