A thick, sepia-coloured haze shrouded the national Capital on Thursday, blurring its skyline and leaving residents coughing and gasping for breath with burning eyes as the city’s air quality deteriorated, underscoring the growing public health crisis.
Delhi’s 24-hour average Air Quality Index (AQI) climbed to 350, firmly in the ‘very poor’ category, from 313 recorded on Thursday. According to the Decision Support System (DSS) for Delhi, transport emissions are expected to account for around 16 per cent of the city’s pollution load on Thursday, while stubble burning is estimated to contribute 8.9 per cent.
Of the 57 air quality monitoring stations that recorded data on Thursday, 10 were in the ‘severe’ category, 42 in the ‘very poor’ category, four in the ‘poor’ category and only one in the ‘moderate’ category.
The Delhi Cantonment monitoring station, however, recorded the city’s best air quality, with a 24-hour average AQI of 138, in the ‘moderate’ category. The station’s 24-hour average AQI stood at 117 on Wednesday and 135 on Tuesday. Before that, it was 297 on Monday, then improved drastically.
Experts, however, said the comparatively low readings at Delhi Cantonment may not reflect cleaner air and could point to an issue with the station’s PM2.5 monitoring instrument. “Green cover cannot explain what we are seeing at the Delhi Cantonment station. This year its PM2.5 reads at only about a quarter of the city level, the second-lowest of 57 stations in Delhi,” Sunil Dahiya, founder and lead analyst at Envirocatalysts, said.
“The station’s PM10 readings, meanwhile, remain at around 60 to 80 per cent of the city level. In the smog season, fine particles normally make up about half of PM10 across Delhi. At Cantonment, they are coming in at just 17 per cent,” he said.
The India Meteorological Department (IMD) reported shallow fog and poor visibility at both Safdarjung and Palam in the morning. At Safdarjung, visibility dropped to 800 metres between 6.30 am and 8 am before improving marginally to 900 metres at 8.30 am. At Palam, visibility remained at 800 metres between 7.30 am and 8 am, improving to 1,000 metres at 8.30 am.
PM10 was the predominant pollutant in the national Capital. Residents had little choice but to brave the thick blanket of dust and smog, with many wearing masks, even as complaints of persistent coughing, burning eyes, and breathing discomfort continued across the city.
The transport sector is expected to remain the largest contributor to Delhi’s pollution over the next few days, while stubble burning’s contribution is likely to remain relatively low, according to a revised forecast released Thursday afternoon. According to the Decision Support System (DSS), the transport sector’s contribution is projected to rise to 18.5 per cent on Friday, even as stubble burning’s share is expected to decline further to 5.3 per cent.
Vehicular emissions accounted for 19.3 per cent of the pollution, while secondary inorganic aerosols contributed 11.9 per cent, the IITM models showed. Experts said secondary organic aerosols originate from several sources, including certain industries, diesel and petrol vehicles, and biomass burning.
According to the Air Quality Early Warning System (EWS) for Delhi, concentrations of particulate matter PM2.5 and PM10 are also expected to increase over the next two days, potentially worsening the city’s air quality. Experts have repeatedly warned about the health risks associated with prolonged exposure to high concentrations of particulate matter, particularly PM2.5, which can penetrate deep into the lungs and enter the bloodstream, affecting several organs.