New Delhi was shrouded in a thick toxic haze Friday after a night of frenzied Diwali fireworks sent the air quality plummeting despite a ban on their sale aimed at thwarting a repeat of last year's 'airpocalypse'.

India's Supreme Court had banned the sale of firecrackers ahead of the Hindu festival of lights to prevent a repeat of last year's post-Diwali air pollution crises that left Delhi's 20 million residents gasping for weeks.

But late Thursday the readings for PM10 pollutants hovered around 1,100 microgram per cubic metre in some parts of the city—11 times above the prescribed air quality levels of World Health Organisation.

PM10 particles measure less than 10 microns or 10 millionths of a metre—several times thinner than a human hair.

Air quality data from the state-run Delhi Pollution Control Committee showed pollution levels in a crowded neighbourhood hit 1,179 around midnight as firework displays reached a crescendo.

Residents of Delhi, rated the most polluted city by WHO in 2014, showed little consideration for the ban, purchasing crackers illegally or using those bought earlier.

The levels had subsided through the night but were still "severe" in several districts across the capital Friday afternoon.

India's Nobel peace laureate Kailash Satyarthi said he was pained by Delhi's nonchalant attitude.

"Delhiites continue to choke on pollution. It is a reflection of our dismissive & disrespectful attitude towards society, law & justice. When will we learn," he wrote on Twitter.

Delhi's woes

The spike in levels came on a day when a report in the Lancet medical journal said pollution had claimed as many as 2.5 million lives in India in 2015, the highest in the world.

Globally the number of deaths due to environmental pollution stood at nine million - three times more than AIDS, tuberculosis and malaria combined, the study said.

Delhi's air quality typically worsens at the onset of winter, due to pollution from diesel engines, coal-fired power plants, industrial emissions and atmospheric dust.

Levels of PM2.5—the finer particles linked to higher rates of chronic bronchitis, lung cancer and heart disease—have soared since the beginning of this month when millions of farmers in the city's north burn post-harvest crop residue.

The court on October 9 had banned sale of firecrackers across the city in anticipation of last year's catastrophic levels of pollution. But it did not put any restrictions on the bursting of fireworks.

Last year's Diwali festivities took pollution levels to a record high—the worst in nearly two decades—forcing the government to shut schools and close down a coal-fired power plant.

On Tuesday an environmental watchdog ordered the shutting down of all diesel generators and the city's lone coal-fired power plant as part of a slew of measures to curb pollution.

Experts however say the air quality will remain considerably cleaner this year, thanks to a favourable wind system.

"The wind system will not allow stagnation of smoke over the city. We will have better air this time," said Gufran Beig, chief scientist at India's state-run System of Air Quality Weather Forecasting and Research.

Explore further New Delhi shuts power plant in fight against Diwali smog

© 2017 AFP