Season’s worst: Delhi's AQI hits severe, but relents after 8 hours

Conditions improved slightly later, but forecasts point to very poor air through November 16. Transport was the largest source of PM2.5 pollution.

Residents in Delhi woke up on Friday to a thick blanket of haze hanging over the city’s skyline, with the air quality index (AQI) remaining in the “severe” category for much of the morning. For eight hours, from the early morning until around noon, the city’s air quality remained in the severe zone, underscoring the worsening pollution situation.

At 8am, 33 of the 58 monitoring stations reporting data recorded “severe” air quality, while 24 were in the “very poor” category and one in the “moderate” category. (Sanchit Khanna/Hindustan Times)

The city’s official AQI crossed into the severe category for the first time this season at 4am. Pollution levels remained at the same mark at 8am and 9am, according to data from the Central Pollution Control Board (CPCB).

The situation was grim in the majority of areas in the city. At 8am, 33 of the 58 monitoring stations reporting data recorded “severe” air quality, while 24 were in the “very poor” category and one in the “moderate” category.

By 9pm, the situation had improved marginally, with 10 stations recording readings in the “severe” category and 44 in the “very poor” category. Four stations were in the “poor” category, while only one station -- Delhi Cantonment -- recorded an AQI in the “moderate” zone.

CPCB classifies an AQI between 0 and 50 as “good”, 51 and 100 as “satisfactory”, 101 and 200 as “moderate”, 201 and 300 as “poor”, 301 and 400 as “very poor”, and 401 and 500 as “severe”.

The improvement in air quality during the afternoon was attributed to changing meteorological conditions and an increase in wind speed, which helped disperse some of the pollutants trapped close to the ground.

However, this respite (if it can be termed that) is likely to be limited. According to the Air Quality Early Warning System (AQEWS), Delhi’s air quality is expected to remain “very poor” from Saturday until November 16. The outlook for the subsequent six days also indicates “very poor” air quality, suggesting that the city is unlikely to see any sustained improvement.

Sources of Delhi’s PM2.5 Pollution

Transport emerged as the biggest contributor to the city’s PM2.5 pollution, accounting for 31.5% of emissions, according to real-time source-apportionment data from the Air Quality Early Warning System and the Decision Support System (DSS).

Secondary organic aerosols were the second-largest contributor at 24.7%. Domestic solid biofuel and dung-cake burning, along with biomass and stubble burning, together accounted for 20.8% of the pollution. Secondary inorganic aerosols contributed 12.7%, followed by waste burning at 5.6%.

Firecrackers accounted for 2.2% of PM2.5 emissions, industrial sources for 1.8%, and mineral dust and ash for 0.6%.

Weather Forecast and Temperatures

The IMD has forecast very light rain on Monday. According to the forecast, very light rain is expected between morning to forenoon at isolated places.

Meanwhile, the city recorded a maximum temperature of 31.4 degrees Celsius, 2.9 degrees above normal, while the minimum settled at 16.2 degrees Celsius, 2.7 degrees above normal, according to the India Meteorological Department (IMD).

Among other weather stations, Palam recorded a maximum of 28.5 degrees Celsius and a minimum of 16.1 degrees Celsius. Lodhi Road recorded a maximum of 30.8 degrees Celsius and a minimum of 17.2 degrees Celsius. The Ridge recorded a maximum temperature of 30 degrees Celsius and a minimum of 17.2 degrees Celsius, while Ayanagar recorded 31 degrees Celsius and 16.3 degrees Celsius, respectively.

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