The level of PM2.5, tiny particulate matter that can clog lungs, is over six times higher than the WHO safe level.

India’s air quality has plummeted to the worst possible category, the government’s Central Pollution Control Board said on Friday.

The level of PM2.5, a tiny particulate matter that can dangerously clog lungs, read 187, more than six times higher than the World Health Organization considers safe.

The board warned people to avoid jogging outdoors in the early morning or after sunset and to keep their medications at hand if they are asthmatic. It also advised people to wear masks as a precaution.

The most recent air pollution data from the World Health Organization released in March this year gave India the dubious distinction of having the world’s 10 most polluted cities.

India’s capital, which once was the world’s most polluted city, ranks sixth. But experts say the data does not suggest that New Delhi’s air quality has improved, rather that more Indian cities’ air has worsened.

A Supreme Court-appointed Environment Pollution Authority warned on Thursday that air pollution in the capital region is likely to peak from November 1 as a change in wind direction brings the toxic fumes from stubble-burning on farms in the neighbouring states of Haryana and Punjab into the region.

“Weather conditions are projected to become adverse from November 1,” warned the India Meteorological Department.

Farmers have been ignoring government warnings of imposing a penalty for burning, saying they can’t afford to buy harvesting machines that cost up to 50,000 rupees ($675) apiece.

A farmer walks through the smoke of burning farming waste at Palwal, Haryana state [File: Saurabh Das/AP Photo]

Another concern is the upcoming Diwali festival; late last year Delhi was covered in a toxic smog caused in part by the countless firecrackers let off for the festival, forcing authorities to shut power stations, ban construction and clamp down on rubbish burning.

“We are heading into a deadly cocktail with Diwali and peak stubble burning time,” an official said on Thursday.

Some activists urged India’s top court to order a complete ban on firecrackers this year as Diwali festival falls on November 7. The court, however, only imposed certain conditions for the sale and use of firecrackers.

Among those was an order that firecrackers could only be set off between 8pm and 10pm on November 7 and can not be sold online. It also set the kind of firecrackers that could be manufactured and sold, limiting them to less-polluting types.

Authorities also are trying to reduce the amount of dust in the air by sprinkling water in many neighbourhoods and ordering builders to cover construction sites.