At a Glance

The level of air pollution in New Delhi is about 11 times higher than the U.S. recommended level.Part of the problem stems from residents who burn small fires when temperatures drop.Other culprits include vehicle and industrial emissions, crop and trash burning, and dust from building sites.

Air pollution has reached emergency levels in New Delhi, India, home to more than 20 million people.

At one point on Thursday, the concentration of poisonous reached 440 in the capital city, according to the state-run Central Pollution Control Board (CPCB).

The level stood at 386 by 7 p.m. local time Friday, about 11 times higher than the United States' recommended level of 35.

According to the CPCB, an Air Quality Index (AQI) level from 201 to 300 is considered poor, 301 to 400 is very poor, and 401 to 500 is severe.

(MORE: Foreign Tourists Skipping Delhi over Air Quality Fears)

Part of the problem stems from residents who burn small fires to keep warm when temperatures drop. Combined with crop burning, vehicle exhaust, industrial emissions from coal-fired plants, dust from building sites and smoke from the burning of waste, air quality is frequently unhealthy for residents. The AQI tends to spike when there is a lack of wind to clear out the particulate matter.

"India's smog problem is due, in part, to the cooler temperatures recently, the lack of big weather systems to move air pollutants around and an ongoing drought across much of the country," said weather.com meteorologist Jonathan Belles. "Satellite images show that smog has been present for at least the last 30 days in India's north, including New Delhi, although some days are worse than others."

A satellite image captured on Thursday shows smog in northern India trapped against the Himalayas.

(NASA)

To help curb the pollution, the country's Environment Pollution Control Authority in the city beginning on Friday, Zee Business reported.

Pollution also spiked in October and November, prompting the government to adopt measures to reduce pollution, including a temporary ban on construction and waste burning.

In October, the Delhi government also began a crackdown on polluting vehicles. Visibly polluting vehicles, overloaded trucks and commercial vehicles were stopped, with penalties ranging from fines to impounding.

In December, authorities ordered firefighters to sprinkle water from high-rise buildings in the capital to settle dust and stop garbage fires, the Associated Press reported.

Most government initiatives to reduce pollution have failed, critics say.

“Climatic conditions have contributed to the crisis, but let’s admit that most have failed miserably,” Sunil Dahiya of Greenpeace India told Reuters.

The Heart Care Foundation of India has noted that can aggravate asthma and other existing lung diseases such as chronic obstructive pulmonary disease (COPD), the Hindu reported.

According to a study published in Lancet Planetary Health in December, in India in 2017 as a result of air pollution. That accounts for 12.5 percent of all deaths in the country. Of the deaths attributed to air pollution, 51.4 percent of victims were younger than 70.