Delhi breathes easier as AQI in ‘poor’ category for third consecutive day

Delhi Pollution: Delhi residents received a respite from toxic pollution levels for the third consecutive day as the city’s AQI remained in the “poor” category on Tuesday.

The 24-hour average Air Quality Index (AQI) of the city was recorded at 268 at 4 pm, registering a slight improvement from 280 on Monday.

Meanwhile, the Decision Support System (DSS), the primary tool used to assess and estimate the sources of pollution in Delhi, has not been updated since Friday.

The latest data available on the DSS website covers November 26 to November 29, with updates for the past four days missing.

A Commission for Air Quality Management (CAQM) official stated that the DSS is still undergoing development and has not yet been fully operationalized.

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“An evaluation committee reviewed the system and found that its data and accuracy did not meet the terms of reference established for the model. Additionally, it was observed that some of the data and the emissions inventory being used were outdated,” the official explained, seeking anonymity.

The official added that DSS could resume providing data once the necessary modifications are made.

Air pollution sources and emission trends across the NCR region have evolved over the years and require updates, the official said, adding providing a specific timeline for the DSS resumption is currently not possible.

When approached, an IITM (Indian Institute of Tropical Meteorology) representative confirmed that the tool is under review. “An expert committee is currently evaluating it,” the representative stated, requesting anonymity.

The last update on November 26 showed stubble burning contributed 5.64 per cent to Delhi’s PM2.5 concentration levels, down from 6.99 per cent on November 25. No further updates on stubble burning have been provided since then.

For November 27 to 29, the DSS estimated vehicular emissions contributed between 21 per cent and 24.6 per cent to the city’s PM2.5 levels, while “other sources” accounted between 22 per cent and 24.6 per cent.

Of the 37 air quality monitoring stations in the city, only five reported air quality in the “very poor” category on Tuesday, while the rest recorded “poor” air quality, according to the Sameer app.

The Central Pollution Control Board (CPCB) classifies AQI between 0 and 50 as “good”, between 51 and 100 as “satisfactory”, between 101 and 200 as “moderate”, between 201 and 300 as “poor”, between 301 and 400 as “very poor”, and above 400 as “severe”.

The primary pollutants on Monday were PM2.5 and PM10, with PM2.5 levels recorded at 105 µg/m³ at 3 pm, while PM10 levels were 204 µg/m³ at the same time on Tuesday. These fine particles pose significant health risks as they can penetrate deep into the lungs and enter the bloodstream.

The Air Quality Early Warning System for Delhi observed that the predominant surface wind on Tuesday was light, with wind speeds of less than 16 kmph until the evening, after which it is expected to decrease to below 10 kmph, coming from the northwest direction during the night.

Smog and mist are likely in the evening and at night, with mainly clear skies expected on Wednesday.

The forecast predicts that the predominant surface wind will be from the northwest, with speeds of less than 10 kmph in the morning. Smog and shallow fog are expected in the morning, with wind speeds gradually increasing to 12-16 kmph from the northwest in the afternoon. Wind speeds will then decrease again to below 10 kmph in the evening and night.

The air quality is expected to remain in the “poor” category from Tuesday to Thursday.

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It was another sunny day for Delhiites on Tuesday, with the daytime temperature recorded at 28.2 degrees celsius, 2.9 degrees celsius above normal, according to the India Meteorological Department (IMD).

The city recorded a minimum temperature of 10.5 degrees celsius, a notch above the season’s average, with humidity levels fluctuating between 96 per cent and 62 per cent during the day.

The weather department has forecast mist for Wednesday, with the maximum and minimum temperatures expected to hover around 26 and 11 degrees celsius, respectively.