Delhi was gasping for breath days ago. How did the air quality improve suddenly?

详细摘要

Delhi's air quality improved from 'very poor' to 'poor' on Sunday as rain and stronger winds dispersed pollutants. The relief may be brief, with weaker ventilation forecast to push pollution back into the 'very poor' category.

Delhi's air quality improved on Sunday, moving from the 'very poor' to the 'poor' category after several days of toxic pollution that had kept the national capital shrouded in a haze following Diwali. The improvement came after better wind speeds and light rainfall helped disperse pollutants, according to weather experts.

The city's Air Quality Index (AQI) stood at 290 at 4 pm, compared with 350 in the 'very poor' category in the morning, according to the Sameer app.

Of the 58 air quality monitoring stations across Delhi, 34 recorded 'poor' air quality, while 23 reported 'very poor' levels. Delhi Cantonment was the only station to record 'moderate' air quality. NSIT Dwarka recorded the worst air quality, with an AQI of 364.

According to the Central Pollution Control Board (CPCB), an AQI between zero and 50 is classified 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'.

Delhi's air quality had remained in the 'very poor' category since November 11, with several hourly readings approaching the 'severe' mark and even crossing it once. The last time the city recorded 'poor' air quality was on November 10, when the AQI stood at 299. Before that, the AQI was recorded at 261 on November 1.

According to real-time PM2.5 source apportionment data from the Air Quality Early Warning System and the Integrated Decision Support System, biomass burning was the largest contributor to Delhi's pollution on Sunday, accounting for 37.1 per cent.

This category includes stubble burning, domestic solid biofuel, and the burning of dung cakes and wood.

Secondary organic aerosols, fine particles that form in the air through chemical reactions involving gases, were the second-largest contributor at 22 per cent. Vehicular emissions accounted for 17.2 per cent, followed by secondary inorganic aerosols at 9.6 per cent.

Waste burning, including municipal waste and waste containing plastic and rubber…

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