New Delhi: Residents of the national capital region woke up on Sunday to a thick shroud of poisonous smog, with air quality deteriorating from the levels seen on Friday when the government declared a public health emergency.

Children complained of sore throat, itchy eyes and nausea as local administrations shut schools and many families fled the capital and its suburbs to escape the toxic air. Poor visibility also forced airlines to divert flights.

The quality of air deteriorated sharply after Diwali as a cocktail of poisonous fumes from illegal crackers hung low over the city. Since then, factors such as burning of farm stubble in neighbouring regions, vehicular emissions and construction dust have made Delhi’s air unbreathable.

The Air Quality Index (AQI) for Delhi was in the severe+ category, at 625, on Sunday morning, according to the System of Air Quality and Weather Forecasting and Research (SAFAR) of the Union ministry of earth sciences. This worsened to 708 by evening.

The air quality was the worst in Gurugram, with an AQI of 833. Noida, which was enveloped in dense smog, recorded extremely hazardous levels of pollution, with the AQI at 720.

(Photo: Sanjeev Verma/HT)
(Photo: Sanjeev Verma/HT)

The concentration of particulate matter (PM) 2.5, a serious threat to the respiratory systems of human beings, touched the season’s highest level of 558 in Delhi, while that of PM10 stood at 648. Many global epidemiological researches show a consistent increase in cardiac and respiratory morbidity and mortality because of exposure to PM2.5.

P. K. Misra, principal secretary to Prime Minister Narendra Modi, held a high-level meeting on Sunday evening through video conferencing with the states of Punjab, Haryana and Delhi to tackle air pollution. It was decided that the cabinet secretary will monitor the situation with these states on a daily basis.

The government has failed to address the air pollution issue effectively despite the worsening of air quality in the region around November every year.

Weather conditions prevailing during this time, coupled with the fact that farmers burn their crops to make way for the next planting cycle, contribute to the annual environmental disaster that threatens the health of millions of residents of the national capital region.

“There was a rapid buildup of pollutants. The unexpected light drizzle last night in a calm wind condition worked highly adversely as there was rapid secondary aerosol formation in the wee hours and PM2.5 concentration multiplied," a SAFAR report said. “The scattered showers increased the holding capacity of the air and the mixing layer height came down to the season’s lowest (of less than 50 metres)."

A cyclist braving the smog in Ghaziabad on Sunday (Photo: Pradeep Gaur/Mint)
A cyclist braving the smog in Ghaziabad on Sunday (Photo: Pradeep Gaur/Mint)

Satellite data, however, showed a drastic reduction in the stubble fire counts across north-west India during the past 24 hours, with the contribution of biomass burning to the pollution coming down from 30% to less than 17%. However, according to scientists, this could also be because of the dense cloud cover, which obscures active fire detections by the satellite.

The problem of stubble burning could heighten, as farmers would have less time for sowing because of the delayed retreat of the monsoon this year and the gap between the rabi harvesting and kharif sowing season decreasing, experts said.

“Stubble burning is not the primary cause of pollution, but it is a major factor behind the deteriorating air quality of Delhi and we cannot deny it," said environmentalist Chandra Bhushan. “Nearly 150 million tonnes of stubble is burnt every year in a short span of 15-20 days."

Delhi’s internal sources of pollution, including transport (which contributed 41% to the total pollution) and industrial (18%), have been steadily rising because of increased urbanization and consumption. There has been a fourfold increase in the number of registered vehicles in the city in the last two decades.

People hold a placard as they form a human chain demanding the government to take immediate steps to control air pollution in New Delhi (Photo: Reuters)
People hold a placard as they form a human chain demanding the government to take immediate steps to control air pollution in New Delhi (Photo: Reuters)

“The pollution load on the capital is only increasing. What we now need is a massive transition in our fuel consumption and not small technological fixes," said Bhushan, former deputy director general of the Centre for Science and Environment. “Move all industries within a radius of 300km from solid fuel to gas. Let’s focus on zero emission vehicles and electrification of the automobile sector. Let’s also replace all coal thermal power plants with renewable energy and try to bring a fundamental change to make farmers stop stubble burning. The exclusive approach to Delhi may not work. The need is for an airshed regional plan."

The air quality in Delhi will remain in the severe category on Monday as well and may improve slightly from Tuesday if the persisting cyclonic circulation increases wind speed, according to SAFAR’s latest forecast.