The annual blanket of air pollution hanging over Delhi is due to a confluence of factors, but it's a serious health threat, and it's getting worse.
New Delhi — Authorities in India stepped up efforts on Friday to address deteriorating air quality as farmers burning crop stubble and calmer winter winds left a thick blanket of haze and smog to choke residents across the Delhi capital region. Factories, construction sites and primary schools were ordered to shut down and Delhi authorities urged people to work from home as dangerous fine particle pollution filled the air.
Delhi's 24-hour average air quality index (AQI), which measures the concentration of very fine particles know as PM2.5 in the air — particularly harmful pollutants as they're easily inhaled and can settle deep in the lungs — crossed 470 on Friday, per the state-run Central Pollution Control Board.
Anything over 300 is classed as "hazardous" on the international AQI rating system, and at "severe" levels, air pollution "affects healthy people and seriously impacts those with existing diseases." On Friday, many parts of Delhi recorded an AQI of more than 600.
Authorities also restricted the operation of diesel-powered vehicles and sent out trucks equipped with water sprinklers and anti-smog guns to try to control the smog.
"We are also mulling over implementing the odd-even scheme for the running of vehicles," Arvind Kejriwal, the Chief Minister of Delhi, said. That would see about half of Delhi's privately owned vehicles ordered off the roads, with odd and even-numbered license plates allowed to operate on alternating days.
Even the air quality monitors installed at the U.S. Embassy in Delhi, which sits in one of the cleanest and greenest patches in the city, registered an AQI over 360 on Friday, well into the most dire, "hazardous" level on the AQI chart displayed on the embassy's website.
Residents of the Indian capital weren't likely to see much improvement quickly, with weather conditions expected to remain calm and the seasonal crop stubble burning likely to continue.
India's Environment Minister, Bhupender Yadav, on Wednesday blamed the opposition-run northern state of Punjab for failing to stop farmers burning off the remains of their harvested summer crops.
"There is no doubt over who has turned Delhi into a gas chamber," Yadav said in a tweet.
unjab's top politician, Bhagwant Mann, defended his administration, saying it only took office half a year ago and calling for a collaborative effort by state and federal authorities to address the problem.
The Delhi government is following a Graded Response Action Plan (GRAP) to combat air pollution in the city. The stricter measures were taken Friday as the average air quality worsened to "Severe Plus," with the AQI over 450.
"It is the responsibility of all of us to take initiative at every level to stop pollution," said Delhi's state environment minister Gopal Rai earlier in the week.
The Indian capital is choked with toxic air most winters thanks to a confluence of factors, but a significant proportion of the smog does come from the huge farm fires in the neighboring states of Punjab, Haryana and Uttar Pradesh.
Many farmers burn off the remains of their crops, the stubble left sticking out of the ground, to prepare their fields for winter crops. It's a much cheaper option than transporting the stubble for proper disposal.