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Post-Diwali pollution may subside from today, Delhi air to clean up by Sunday

Experts said the city’s pollution levels turned poor not just because of the smoke from crackers and vehicles, but mostly due to the high levels of moisture in the air.

delhi Updated: Oct 21, 2017 08:44 IST
Joydeep Thakur
Joydeep Thakur
New Delhi, Hindustan Times
Diwali,Pollution,Diwali pollution
A man wears a mask as smog covers Rajpath after Diwali celebration in New Delhi, on Friday.(Arvind Yadav/HT PHOTO)

If you’re having trouble breathing after Diwali, then you may have to wait till Sunday for some clean air.

Weather department officials have forecast that the post-festival pollution is expected start dissipating from Saturday and will likely fall back to pre-Diwali levels from Sunday. Officials said the air quality may begin improving from Saturday with a change in wind direction, an increase in wind speed and a drop moisture content in the air.

By Sunday, Delhi’s air would be cleaned up completely, officials added.

“Even though there could be some improvement on Saturday as the moisture content is expected to drop, we would need some strong dry winds for the pollutants to clean up. For this, we would have to wait till Sunday,” said VK Soni, head of the environment monitoring research centre of the Indian Meteorological Department.

High moisture aggravated pollution

Experts said the city’s pollution levels turned poor not just because of the smoke from crackers and vehicles, but mostly due to the high levels of moisture in the air.

The easterly winds that were gushing in, brought heavy amounts of moisture, which created the fog that was seen on Friday morning. The moisture helped the pollutants to linger in the air longer as a result of which several areas in Delhi which had greenery such as Lodhi Road witnessed severe levels of pollution.

There would, however, be a drop in the moisture from Saturday and visibility is expected to increase.

“The dry north-westerly winds are picking up. Once they get stronger the pollutants would be flushed out as the carrying capacity of the air would drop,” said Kuldeep Srivastava, a scientist with the regional weather forecasting centre in New Delhi.

Farm stubble pollution the next challenge

However, once the north-westerly winds start blowing in, Delhi would have another concern. These winds would be coming in from those regions where stubble burning is prevalent – Punjab and Haryana.

“Crop residue burning started this year in September last week and is likely to continue till last week of November. We are already into the peak period, and this would continue till the second week of November, after which there would be only sporadic incidents,” said S Narayanan, member secretary of Haryana Pollution Control Board.

But Met officials said that till the time winds remain strong, Delhiites need not worry.

“The north-westerly winds do bring in pollutants from stubble burning regions, but they won’t be affecting the national capital as the current would be strong. The pollutants would just pass through,” said Srivastava.

It is only when the winds slow down or there is some system like an anti-cyclonic circulation over the region that the pollutants settle down and play havoc in Delhi. Moisture aggravates this situation.

It may be recalled that in 2016 an anti-cyclonic circulation had played havoc resulting in smog in Delhi. A few days before Diwali, wind speed had dropped to around 10 km per hour, resulting in a spike in pollution levels.

First Published: Oct 21, 2017 08:34 IST