Air in Delhi gets fouler, fog to envelop city starting Wednesday

Air quality in the Capital dipped on Tuesday even as fog covered the city in the evening.

Air quality in the Capital dipped on Tuesday even as fog covered the city in the evening.

The air quality is likely to get fouler over the next couple of days. (Sanjeev Verma/HT Photo)

The air quality is likely to get fouler over the next couple of days.

On Tuesday morning, the 24-hour rolling average of PM10 and PM2.5 touched poor and very poor limits respectively, according to System of Air Quality Weather Forecasting and Research (SAFAR) data, reading 334 and 142 microgram per cubic metre respectively. Air quality in Delhi continued to be in “very poor” category with Air Quality Index clocking 317 on Tuesday.

However, as the day progressed PM2.5 levels reached 174g/m³ in a matter of few hours.

“Cold winds from the Indo-Gangetic Planes are bringing in pollution to the Delhi region and as a result air is getting fouler. The air quality will keep getting worse till Thursday when PM2.5 is expected to touch 200g/m³,” Gufran Beig, programme director of Safar, which comes under the earth sciences ministry, told HT.

PM2.5 and PM10 are ultrafine particles — the dominant pollutants in Delhi. The 24-hour prescribed standards of PM 2.5 and PM10 are 60 and 100 microgram per cubic metre, respectively.

According to Safar advisory, people with existing heart or lung diseases such as asthma, congestive heart or ischemic heart diseases are advised to avoid heavy exertion when the air quality is “very poor”.

With patterns and directions changing, dense fog is expected to return to Delhi soon. “We have forecast dense fog for December 8 and 10 (Thursday and Saturday). But this may persist on December 7 and December 9 too (Wednesday and Friday),” said a scientist at the Regional Weather Forecast Centre (RWFC).

However, other weather experts have said that dense fog is expected from midnight on Tuesday. “In Delhi the duration of fog is longer because of the pollution. All Met parameters indicate dense fog will start from Wednesday morning and will continue till 10am,” said RK Jenamani, director, IGIA Met department.

The change in weather comes with the return of easterly winds. “There is also a cyclonic movement of air over the Bay of Bengal. These factors increase moisture in the air, which in cold climates can lead to fog,” a scientist said.

Experts say pollution is going up because of environmental conditions in absence of stringent emission control measures.