The air quality in Delhi improved from "very poor" to the "poor" category on Wednesday due to favourable wind speed, light rains in neighbouring states and a sharp drop in emissions from stubble burning. The 24-hour average air quality index (AQI) stood at 260 on Wednesday, dropping from 372 on Tuesday, PTI reported.
This is the lowest AQI in Delhi since October 20, when it was 232, according to data from the Central Pollution Control Board. An AQI between 201 and 300 is considered 'poor', 301 and 400 'very poor', and 401 and 500 'severe'.
The improvement in air quality comes as schools in the national capital reopened for primary classes from Wednesday. High pollution levels had prompted the Delhi government to close primary schools from Saturday and permitting work from home for 50 per cent of its staff.
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On Wednesday, visibility levels also saw a significant improvement, with 1,400 metres at the Palam airport and 1,500 at the Safdarjung airport in the morning. Visibility levels were 800 metres at these places on Tuesday.
A Met official said southeasterly winds gusting up to 30 kmph through parts of Delhi on Tuesday night helped improve the air pollution situation, PTI reported.
Delhi recorded a minimum temperature of 16.9 degrees Celsius, three notches above normal. The maximum temperature settled at 30.2 degrees Celsius on Wednesday.
VK Soni, the head of the India Meteorological Department's Environment Monitoring and Research Centre, told PTI that parts of east Rajasthan such as Alwar, Bhiwadi and Rewari and some areas in Haryana reported sporadic rains under the influence of a western disturbance.
"The rainfall reduced the share of pollutants from these adjoining areas in Delhi's pollution," he said.
He said that favourable wind speed -- 10 to 18 kmph -- from November 11 would likely bring a considerable improvement in the air quality. Moreover, farm fires in Punjab increased from 605 on Tuesday to 1,778 on Wednesday.
The Commission for Air Quality Management is likely to convene a meeting on Thursday to review the situation and revoke the curbs in Delhi-NCR under stage 3 of the Graded Response Action Plan.
BS-III petrol and BS-IV diesel four-wheelers were asked to stay off roads in Delhi under stage 3 of GRAP. Violation of the ban would attract a fine of Rs 20,000. Vehicles deployed for emergency services, and government and election-related work are exempted.
(With PTI inputs)