After three days of high levels of air pollution, experts said on Thursday that Delhi and other parts of northern India are likely to get some relief with a thunderstorm around Friday night. There have been high levels of particulate matter in the Capital since Tuesday. On Wednesday, 13 people died in Uttar Pradesh after severe dust storms.

A combination of factors have influenced this condition, said Charan Singh, a scientist with India Meteorological Department. Westerly winds normally flow over north west and central India at this time of the year, just before the monsoon sets in. Ordinarily, these are balanced by easterly winds from the Bay of Bengal branch of the south west monsoon.

However, this year, the easterly winds are weaker than usual over the foothills. With dry weather and high land temperatures, dust-bearing winds rose in north west India. The weak easterly winds could have contributed indirectly to the phenomenon, Singh said.

“This is not unusual,” said Singh. “It is usual, but not frequent every year. The monsoon reaches north west India only at the end of June. Before that, there is normally some thunderstorm activity of the kind called ‘andhi’. This dust storm is suspended now because of stable conditions of North West India for two days.”

The phenomenon is not linked to the Arabian Sea branch of the monsoon, which is currently stationary over peninsular India and is unlikely to move further north for at least a week, according to forecasts from the India Meteorological Department.

Jaipur is already clear of the dust storm, said the duty officer at the Meteorological Centre at Jaipur. Wind speeds have been moderate in Rajasthan at around 28 kilometres per hour.

In Uttar Pradesh, 13 people died and 28 were reported injured on Wednesday in different parts of the state, as wind speeds went beyond 75 kilometres per hour for more than two hours. Chief announced financial Another round of thunderstorms and dust storms hit northern India at the end of May and in early June.

In Delhi, however, the winds have pushed pollution to levels that usually prevail in winter, with high levels of stagnant particulate matter, particularly PM10, which are particles the width of 10 microns.

The last time Delhi saw summer pollution like this was over two days in June 2016 and before that in 2015, the Hindustan Times reported a Central Pollution Control Board official as saying. As of 4 pm on Thursday, the PM10 level in Delhi was 914, but had touched 999 in the last 48 hours. India’s air quality instruments are not capable of measuring pollution beyond this level. PM2.5 levels touched 548 in parts of the capital on Thursday. Both these measurements reflect a hazardous quality of air.