Moving smoke clouds raise alarm

Irrespective of whether it is the same source or not, they agreed that local pollution can accumulate and travel great distances depending on meteorological conditions, in this case to the Bay of Bengal and beyond.

Satellite maps showing a plume of smoke filled with PM10 and PM2.5 particulate matter travelling from northwest India past the Indo-Gangetic plains into the Bay of Bengal, and then moving southwards towards Chennai, grabbed the attention of researchers and scientists on Monday.

The Earth Null School map, which isolates PM 2.5 and PM10, along with wind data, shows the plume travelling. Representative image.(Sushil Kumar/HT PHOTO)

Some experts said the deadly smog in Delhi on Sunday may be linked to the moving smoke clouds, while experts at India Meteorological Department contended the particulate matter near Chennai may be from a different source altogether.

Irrespective of whether it is the same source or not, they agreed that local pollution can accumulate and travel great distances depending on meteorological conditions, in this case to the Bay of Bengal and beyond.

“Our Copernicus model is also showing the plume travelling. Maybe its blowing across because the winds are strong and carrying local pollution with it. But the smoke near Chennai could be from a different source. It could be sea salt particles. We are assessing this,” said M Rajeevan Nair, secretary, ministry of earth sciences.

The Earth Null School map, which isolates PM 2.5 and PM10, along with wind data, shows the plume travelling.

“This map just shows wind vectors and pollution movements... we have the same at a higher resolution online,” said Sarath Guttikunda, scientist and founder director of urbanemissions.info.

Forecast maps for November 5, 6 and 7 also show the particulate matter levels increasing in certain parts in southern India, including Tamil Nadu and Andhra Pradesh. The air quality index in Chennai was in the moderate category on November 3, with an AQI of 107. It went up to the “poor” at 262 on Monday.

“I don’t think the stubble fires would have travelled so far. It could be that local pollution is blowing with the wind and sea particles are also accumulating. Moreover, winds are northeasterly in Chennai. It’s impossible that the pollution from here travelled up to Chennai ,” said an India Meteorological Department official, asking not to be named.

He added that wind speed has been good over Delhi at around 15 to 20 kmph since Sunday night, and direction continues to be northwesterly.

Raj Bhagat Palanichamy, a remote sensing analyst at World Resources Institute tweeted: “Not just Delhi, most of India is hit by air pollution crisis. Dispersion models show the plume is travelling across India.”