Air quality worsens in Delhi as weak winds trap pollutants

New Delhi: Delhi's air quality worsened on Sunday as weak winds trapped pollutants, raising the overall AQI to 366 in the "very poor" category with three monitoring stations recording "severe" air above 400, Centre Pollution Control Board data showed.

The PM2.5 concentration stood at 189.6 micrograms per cubic metre and PM10 at 316. PM2.5 refers to the fine inhalable particles with diameters that are 2.5 micrometres or smaller, while PM10 includes slightly larger particles up to 10 micrometres in diameter, according to the CPCB.

At such levels, these pollutants can cause breathing discomfort, especially among people with lung or heart diseases, children and the elderly.

The overall air quality index (AQI) rose sharply to 366 from 303 recorded a day earlier, CPCB data showed.

Haryana's Dharuhera recorded an AQI of 434, falling in the "severe" category, while Bhiwandi in Maharashtra registered "very poor" air at 376 -- both worse than Delhi.

Neighbouring cities in the National Capital Region (NCR) also reported "very poor" air quality -- Ghaziabad (351), Gurugram (357), Noida (348) and Greater Noida (340). Faridabad, however, recorded "poor" AQI at 215.

According to the Air Quality Early Warning System (AQEWS) for Delhi, the wind speed dropped below 8 kmph from the northwest direction during evening and night hours, reducing the dispersion of pollutants.

It added that a ventilation index lower than 6,000 m ²/s and wind speeds less than 10 kmph are unfavourable for pollutant dispersal.

The air quality is likely to remain in the "very poor" category till November 4, the AQEWS said.

Three monitoring stations in the capital recorded "severe" air quality with readings above 400, with Wazirpur reporting the highest level at 413.

Another 28 stations registered "very poor" air quality with readings above 300, according to CPCB's Sameer app.

An AQI between 0 and 50 is considered "good", 51-100 "satisfactory", 101-200 "moderate", 201-300 "poor", 301-400 "very poor" and 401-500 "severe", according to CPCB standards.

The maximum temperature in Delhi was recorded at 30.7 degrees Celsius on Sunday, 0.5 degree below the seasonal average, while the minimum settled at 16.8 degrees Celsius, 1.5 notches above normal, according to the India Meteorological Department (IMD).

The humidity stood at 75 per cent at 5.30 PM.

The weather office has forecast shallow fog for Monday, with the maximum and minimum temperatures likely to hover around 30 and 15 degrees Celsius, respectively.

A ban on the entry of commercial vehicles not registered in Delhi and not compliant with BS-III or lower emission standards came into force in the national capital on November 1.