Delhi records 4 days of 'moderate' air quality in Dec for the first time

New Delhi: Delhi’s air quality returned to 'moderate' category on Monday, marking the highest number of moderate air quality days -- four -- ever recorded in December.

The capital also recorded its lowest daytime temperature this winter season so far, with maximum temperature settling at 21.6 degrees Celsius, 3.2 notches below normal, according to the weather department.

The second-lowest maximum temperature was recorded on November 18 at 23.5 degrees Celsius, as per the data.

Signaling a welcome improvement after the recent fluctuations in pollution levels, the Air Quality Index (AQI), which was in the 'very poor' category on Sunday at 302, improved to 186 by 4 pm on Monday, placing it in the 'moderate' category.

According to the data, Monday marked the fourth moderate air quality day this month, the highest number of such days recorded in December so far.

Data showed that the highest record was set in 2022, 2019, and 2015 when December had three days of moderate air quality. In contrast, no moderate air quality days were reported in December 2023.

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 'very poor', and above 400 as 'severe'.

Of the 38 air quality monitoring stations in the city, only Shadipur recorded air quality in the 'very poor' category on Monday, marking a drop from the 'poor' category recorded on Sunday.

Thirteen stations recorded air quality in the 'poor' category, while the remaining reported 'moderate' AQI, according to the Sameer app.

The primary pollutants on Monday were PM2.5 with levels at 70.9 µg/m ³ 4 pm. These fine particles pose significant health risks as they can penetrate deep into the lungs and enter the bloodstream.

Meanwhile, the Decision Support System (DSS), a tool used to assess and estimate sources of pollution in Delhi, which had not been updated since November 29, has been restarted, showing data from Monday.

According to the DSS, the daily mean of local and non-local fractional contributions to PM2.5 in Delhi on Monday indicated that transport contributed 12.135 per cent, while Tuesday’s forecast predicts it will contribute 20 per cent to Delhi’s pollution.

The forecast for Delhi’s air quality suggests it is likely to remain in the 'poor' category from December 10 to 12, according to the Air Quality Early Warning System for Delhi.

The air quality showed improvement at the start of December, shifting from 'very poor' to 'poor' category, and then further to 'moderate' category.

However, Sunday saw a sharp deterioration as the air quality slipped back to 'very poor' category from 'moderate'.

Delhi also recorded its coldest day of the season on Monday with minimum temperature at 8.2 degrees Celsius, 1.4 notches below normal, according to the India Meteorological Department. Humidity levels during the day fluctuated between 100 per cent and 65 per cent.

The IMD has predicted that maximum and minimum temperatures on Tuesday are likely to hover around 23 degrees Celsius and 7 degrees Celsius, respectively, with moderate fog expected.