Delhi's air quality continued to be in the "poor" category Tuesday, a day after it had improved from "very poor" Air Quality Index (AQI) zone.
The Central Pollution Control Board (CPCB) recorded the city's overall Air Quality Index at 252 at 11 am.
An AQI between 0 and 50 is considered 'good', 51 and 100 'satisfactory', 101 and 200 'moderate', 201 and 300 'poor', 301 and 400 'very poor', and 401 and 500 'severe'.
The air quality in the national capital had shown signs of improvement Monday as it moved from 'very poor' to 'poor' category, but experts said it could deteriorate in the coming days due to toxic air coming out of a fire at Bhalswa landfill site.
The fire was extinguished Monday by a team of firefighters even as the area's civic body said it was keeping a watch on it, while Delhi Environment Minister Imran Hussain directed the municipal corporation to work on preventing landfill site fires.
The Centre-run System of Air Quality Forecasting and Research (SAFAR) also reported an AQI in the 'poor' category.
On Sunday, the Air Quality Index had oscillated between 'poor' and 'very poor' categories.
On Saturday, a haze had engulfed the national capital and the worst air quality of this season was recorded at 324.
Anumita Roychowdhury of Centre for Science and Environment (CSE) Monday said, as winter approaches, toxic air emanating out of such landfill fires is likely to affect the air quality.
"If the wind speed is lower and the temperature dips, the polluted air coming out of landfill fires will get trapped, which would severely affect the air quality," she said.
The Supreme Court-appointed Environment Protection Control Authority (EPCA) had last week held a meeting with officials of Punjab, Haryana and the Delhi governments to discuss the pollution situation in the national capital.
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