In the wake of 15 schoolchildren dying in a tragic bus accident in Uttar Pradesh, reportedly due to foggy conditions, a renowned atmospheric scientist has called for an immediate end to practices that include the operation of traditional brick kilns in the region and the burning of crop residue in Punjab.

The accident at Etah, in which 16 schoolchildren were also injured, reportedly took place under bad weather conditions and poor visibility.

Ramesh Singh, a professor at Chapman University in California who is currently visiting his Varanasi home town, said the government must stop operation of old brick kilns responsible for injecting black carbon and suspended particles in the atmosphere that contribute to the haze.

In particular, the Varanasi region — Prime Minister Narendra Modi's Lok Sabha constituency — "is densely populated by brick kilns which emit black smoke", Ramesh Singh told this correspondent in an email.

"The operation of these old kilns must stop and they should be replaced by non-polluting kilns using new technology to minimise fog and protect the health of people living in the Indo-Gangetic Plain," the scientist added.

Ramesh Singh, who was formerly at the Indian Institute of Technology – Kanpur had studied the dynamics of atmospheric aerosols and cause of the poor air quality over the Indo-Gangetic Plains by analysing data from NASA satellites.

"We found that the main cause of atmospheric pollution and poor air quality in this region is dense population of coal-based power plants, brick kilns, and now growing vehicles on the highways," he said.

Ramesh Singh said his studies have shown that burning of crop residues in Punjab in the months of October and early November "causes fog, haze and smog depending on the meteorological conditions, wind speed and direction and relative humidity, with the smoke plume dispersed over the entire Indo-Gangetic Plain."

"Since the last two decades, we have observed growing fog, haze and smog in the Indo-Gangetic Plains and, during the winter season, visibility becomes so poor that people cannot see objects even 10 metres away," he said. "Cancellation of flights, late running and cancellation of trains are regular features in this region."

Although the central government initiated steps to stop the burning of crop residue in Punjab, Uttarakhand and western UP, "farmers are still burning their crop residues and the smoke spreads over the major cities in the Indo-Gangetic Plains," Ramesh Singh said.

Pointing out that Varanasi experienced "thick fog" late last year, he warned that "people will face more problem in years to come", if no action was taken to stop emissions from brick kilns. The emissions provide very high concentrations of particulate matter that can lead to health problems, he said.

"It is good that Prime Minister Modi has decided to build a Cancer Institute in Benaras Hindu University," he said, "but people must demand an end to the operation of old brick kilns that spew black carbon."