Delhi’s air quality in emergency zone on coldest December day

Dec 23, 2018 10:59 PM IST

The India Meteorological Department (IMD) has forecast that another cold wave could hit Delhi in the middle of the week.

It was a cold, polluted and foggy Sunday in the Capital. While the temperature in the early hours dropped to 3.7 degrees Celsius, making it the coldest December night in four years, pollution levels breached the emergency mark once again. The last time the air pollution reached the emergency level was during the post-Diwali period in November.

Vehicles navigate through dense fog in Gurugram.(Yogendra Kumar/HT Photo)
Vehicles navigate through dense fog in Gurugram.(Yogendra Kumar/HT Photo)

The India Meteorological Department (IMD) has forecast that another cold wave could hit Delhi in the middle of the week. Chances of respite from such high levels of pollution are low in the next two to three days, government agencies said.

A multi-agency task force headed by the Central Pollution Control Board (CPCB) has already advised people with respiratory ailments to minimise exposure to such toxic air.

Citizens have been urged to reduce the use of private cars. While measures such as shutting down the Badarpur power plant, closing brick kilns and banning diesel generators are already in place, some more such as a ban on construction activities, rolling out the odd-even road rationing scheme and closing schools could be announced.

“The night temperature dropped to 3.7 degrees Celsius on Sunday because of cold northwesterly winds and a clear sky. It is the coldest December day since 2014. The temperature had dropped to 2.6 degrees in December 2014. In the last three years though, the temperature hasn’t dropped below 5 degrees in December,” said an official from the IMD.

The city was also engulfed in a moderate fog cover with visibility dropping to less than 500m. While within the city, the visibility dropped to around 400m in the morning, in Palam it was even lower at 300m.

“Even though the average Air Quality Index (AQI) value of Delhi worsened from 421 on Saturday to 450 on Sunday and remained in the ‘severe’ category, the concentration of particulate matter – PM10 and PM2.5 – crossed the ‘emergency’ or ‘severe-plus’ level mark in Delhi and NCR,” said a senior official of the CPCB.

The last time when concentration of pollutants in the air had breached the emergency mark was during the post-Diwali period. The AQI had shot up to 486 then. On a scale of 0-500, an AQI value above 400 is considered to be ‘severe’.

“On Sunday around 5 pm, the concentration of PM10 shot up to 553ug/m3, while the level of PM2.5 touched 377ug/m3. On November 9, after Diwali, the level of PM10 had touched 565ug/m3 and PM2.5 had shot up to 453ug/m3,” said a CPCB official.

While the daily permissible limit of PM10 is 100ug/m, a value above 500 is considered to be an emergency situation. In case of PM2.5, while the safe standard is 60ug/m3, a value above 300 is considered to be an emergency.

“The night temperature could rise by a degree or two over the next two to three days because of an approaching western disturbance. It would however dip again after the disturbance passes away. We are expecting another cold wave around December 26 and 27,” said the IMD.

The IMD has also forecast that moderate fog could engulf Delhi over the next two days because of low night temperature, low wind speed and heavy moisture levels.

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