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Delhi's air expected to slip into 'poor' from today as winds drop and farm fires rise
The early warning system expects the season's first spell of poor air on Wednesday and Thursday, with no rain in sight and the Diwali run-up ahead. Monday's 4 pm average was 139.
Key points
- Delhi's air is forecast to turn poor on 21 and 22 October, and stay poor for six days after.
- The city's 24-hour average AQI was 139 at 4 pm on Monday; Tuesday began at 161.
- Satellites picked up 98 farm fires across north and central India on 19 October.
Delhi’s air is expected to slip into the “poor” category from Wednesday, the start of what forecasters warn could be a long stretch of bad air as the capital heads into the Diwali season with dry skies and little wind.
The Air Quality Early Warning System expects air quality to deteriorate from moderate to poor on Wednesday and Thursday, 21 and 22 October, and its outlook for the six days after that also shows poor air. The cause is the weather: when the ventilation index falls below 6,000 square metres per second and average winds drop under 10 kmph, pollutants hang over the city instead of dispersing.
The city’s 24-hour average Air Quality Index (AQI) stood at 139, in the moderate band, at 4 pm on Monday, according to the Central Pollution Control Board (CPCB). Of the 58 monitoring stations that reported data, two were already in the poor band, six were satisfactory and the rest moderate. Pusa had the worst reading, at 281. On Dussehra morning, the AQI was 161 at 9 am.
Cold nights, still air
The early chill is part of the problem. Safdarjung recorded 17.1 degrees Celsius on Monday morning, 1.3 degrees below the seasonal average and the lowest minimum of the month so far. The India Meteorological Department expects mainly clear, dry weather until 25 October, with maximum temperatures of 32 to 34 degrees and minimums of 19 to 21 degrees, and no rain for Delhi.
Without rain to wash the air, there is little to break the build-up. The weekend had already given a taste: on Sunday the AQI was 187, at the top of the moderate range, and 22 monitoring locations recorded poor air.
Farm fires pick up
Smoke from crop residue burning is starting to add to the load. Satellite monitoring by the Indian Agricultural Research Institute counted 98 farm fire events on 19 October, with 27 in Uttar Pradesh, 25 in Punjab, 24 in Rajasthan, 18 in Uttarakhand and 4 in Madhya Pradesh.
The Commission for Air Quality Management has deployed flying squads in 34 districts of Punjab and Haryana from 1 October to 30 November to check stubble burning.
A bad start to the season
October began badly. The average AQI for the first four days of the month was 174.5, the second worst for that period since 2020, after September had been the cleanest in five years with an average of 102. Rain earlier in the month brought brief relief before the dry spell set in.
The Municipal Corporation of Delhi has put its winter action plan into operation, with 66 mechanical road sweepers, 167 water sprinklers and 28 mobile anti-smog guns on the roads, and special monitoring at 46 pollution hotspots identified by the Delhi Pollution Control Committee.
What poor air could trigger
A move into the poor band (AQI 201 to 300) is the point at which curbs under the Graded Response Action Plan begin. The Commission for Air Quality Management invoked Stage I of the plan in May this year when Delhi’s AQI rose to 208. Further stages, with tighter restrictions, follow if readings climb into the very poor (301 to 400) and severe (above 400) categories.