By Neha Dasgupta and Alasdair Pal
NEW DELHI (Reuters) - India's capital is set for a "deadly cocktail" of pollution in coming weeks, a senior government official said, as air quality in the New Delhi area plummeted on Wednesday, alarming doctors and environmentalists.
The federal government official blamed the deterioration in air quality to a "very poor" level across much of the city on a fall in temperature and lighter wind, as both seasonal changes allow pollution to accumulate.
The official - speaking on condition of anonymity due to the sensitivity of the situation - said air quality would continue to worsen around Diwali, which falls on Nov. 7.
Pollution levels will be exacerbated as farmers in areas close to Delhi burn crop residue in preparation for new planting and people let off fireworks to mark the Hindu festival.
"We are heading into a deadly cocktail with Diwali and peak stubble burning time," the official said.
"If we come back into the 'poor' category of pollution, it will be a very big achievement."
On Wednesday, air quality in Delhi hit the "very poor" level at more than half of its monitoring stations, according to the government's Central Pollution Control Board - the worst set of readings since a dust storm hit the city in June.
Late last year, Delhi and a large part of northern India were covered in a toxic smog from burning crop waste and the countless firecrackers let off for Diwali, forcing authorities to shut power stations, ban construction and clamp down on garbage burning.
Despite pressure from health experts, the government this year held off on a wholesale ban on fireworks and has faced criticism for failing to prevent farmers in states neighbouring Delhi from burning stubble.
To curb pollution levels around Diwali, the country's top court on Tuesday only allowed the use of "green" firecrackers, but it was unclear how the rule will be enforced or whether there was such a thing as an environmentally safe firework.
Despite a government plan to discourage the burning of crop residue by offering to pay up to 80 percent of the cost of certain farm equipment, many farmers are still burning their waste.
On Wednesday at two monitoring stations in Delhi, the air quality index, an international standard measure of several kinds of poisonous particulate matter, exceeded 600, according to the Delhi Pollution Control Committee.
That is a dozen times more than a healthy level of 50. Several other stations reported readings above 500.
Dr J.C. Suri, a consultant in respiratory medicine at Mejeedia Hospital, said he was expecting a spike in admissions of patients with pollution-related health issues.
"Right now, the patient load is similar to usual, but as the air quality deteriorates it is going to increase in the coming weeks," he said.
The World Health Organisation said this year India was home to the world's 14 most polluted cities, with Delhi ranked sixth.
"The government has no political will and year after year we get into a narrative around pollution only in the month of October when the situation is really, really bad," said Vimlendu Jha, an environmentalist who founded the activist group Swechha.
"Almost 320 days out of the 365, Delhi's air quality is in poor condition but there is no conversation around it."
(Reporting by Neha Dasgupta and Alasdair Pal in NEW DELHI; Edited by Martin Howell, Robert Birsel)