What caused the haze over Delhi on Tuesday? It wasn’t the fire raging in refineries in Iran, says top expert

“This is due to the ongoing transition from La Niña to El Niño (warm and cool phases of a natural climate pattern across the tropical Pacific), which make large-scale wind patterns more erratic,” he said.

Dr Beig explained that as Northern India received very little winter rain, the soil remained extremely dry and temperatures have risen much earlier than usual — about 5-7°C above normal in some places.

“At the same time, there has been contrasting weather patterns across North India with continued snowfall in the Kashmir region. When a Western Disturbance from the Gulf (a weather system that brings moisture from the west) moved into the region, it carried moisture into the atmosphere and pushed it towards northern India, including Delhi,” Dr Beig said.

Because one region was very hot and dry while another was cool and moist, a temporary haze formed in the air. However, it lasted only briefly, and the skies cleared the next day as the high temperatures helped disperse the moisture.

Mahesh Palawat of Skymet Weather Services added that strong south-westerly winds from Balochistan, Central Pakistan and the Thar Desert in Rajasthan also contributed to the haze. He noted that while such haze events have occurred before, they are relatively rare.

And why is it unlikely that oil refineries burning in Iran could affect India?

Dr Beig said he had investigated the possibility — and found no strong reason to believe that it could be true.

“During this period (March), winds flow from the Iran-Iraq-Afghanistan belt towards India. When the temperature warms up in the desert, it causes dust storms that travel all the way to Western port cities like Mumbai and neighbouring places, sometimes it penetrates Northern India as well.”

“That and the smoke due to the war combined…may [in theory] affect [India]. But our investigation shows that the aerial distance is around 2,000 km and the plume has travelled only about 500 km, and has already become highly diluted. The particles remain airborne for about two to three days before breaking down,” he added.

For the pollution to reach India, the fire would have to produce a very large volume of smoke, which would move at high speed, and rise to a greater height in the atmosphere, he said. And this has not happened in the present case.

“Therefore, the possibility that the haze seen in Delhi was caused by fires in the Gulf region can be ruled out for now,” he said.