Delhi enjoys ‘poor’ air, clear sky; likely to worsen again

Winds at 28kmph flushed out dust, but the speed may drop to 6kmph on Tuesday, with clouds to return on Wednesday

NEW DELHI : The city’s clear blue skies made it to the headlines on Sunday as air quality in Delhi improved to become ‘poor’, after nearly a five-day long spell of being in the “severe” zone. However, the relief is expected to be short-lived, as conditions are again likely to deteriorate from Wednesday (November 20) when a cover of clouds and fog will return, government agencies warned.

The average air quality index (AQI) for day, calculated by the Central Pollution Control Board’s (CPCB) , was 215. This was against the overall AQI reading of 357 on Saturday. The air quality had recovered to ‘very poor’ levels after reeling under ‘severe’ zone between November 12 and November 15.

“Air quality will continue to be in ‘poor’ category on Monday.

However, it may dip on Tuesday with slowing down of winds and may fall into ‘very poor’ zone,” as per the forecast bulletin released by the air quality early warning system of the union ministry of earth sciences (MOES).

Scientists at the India Meteorological Department (IMD) said strong winds and clear sunlight bailed the city out of the pollution emergency. They said that the average wind speed on Sunday was 28-30 kmph, which flushed out pollutants accumulated in the air.

“During the day the wind speed went up to 36 kmph for a few hours, which helped significantly cleanse the air of the layer of pollutants. The wind speed will drop to 15-20kmph on Monday. However, it will slow down to 6-8 kmph on Tuesday, when air quality may dip again,” said a senior IMD scientist.

The scientists warned the air quality could deteriorate further on November 20 -21 due to a host of factors --- low wind speed, cloud cover, moderate fog and drop in mercury, which together result in a toxic combination of smog.

“High moisture content in fog traps pollutants while cloud cover bars sunlight from reaching the surface. With a drop in temperature, the air becomes cold and heavier. All these factors lead to accumulation of pollutants, which could not be dispersed if wind speed is low, resulting in the deterioration of air quality,” said Kuldeep Srivastava, head, regional weather forecasting centre (RWFC), IMD.

The CPCB-LED task force had reviewed the pollution levels on Saturday and lifted the ban on industries run on coal.

Schools also reopened in the city, which were shut on Thursday-friday after deterioration in air quality.

Delhi CM Arvind Kejriwal had said that he will take a decision whether to re-introduce the odd-even road rationing scheme, on Monday.

Also, if the CPCB-LED task force come out with an advisory of shutting down schools in wake of bad air quality, the Delhi government will follow the directions. The government had implemented the odd-even scheme during November 4-15.