Residents in India's New Delhi woke up to a city covered in dense fog and low visibility on Monday morning.

According to a report by broadcaster NDTV, at least 29 trains and 150 domestic flights were delayed.

The Delhi Airport issued an alert that due to the "dense fog" flight operations may be affected throughout the day.

Visibility was down to 200 meters in the early hours of Monday morning. Vehicles were moving slowly with hazard lights on, reported NDTV.

The India Meteorological Department (IMD) tweeted an image showing the visibility data across northern India. It also said that power lines in areas of dense fog could trip and cause electricity outages.

Delhi grapples with fog and cold wave

Over the past week, Delhi and other northern states have been grappling with an acute cold wave and increased fog.

On Sunday, the capital recorded a minimum temperature of 3.8 degrees Celsius (38.8 degrees Fahrenheit), which is the second lowest in the last decade. According to the IMD, the figure is 3 degrees below normal for this time of the year.

Earlier in December it was reported that Delhi was experiencing an unusually warm winter.

The Indian Express reported that maximum temperatures in the second week of December touched 39 degrees Celsius, which is four degrees above normal for that time of the year.

The cold wave has forced authorities to defer school reopenings by a week. Many private schools were set to reopen on Monday.

Early in November 2022,  schools were also shut down due to heavy pollution. 

Winter proves to be dangerous and sometimes even fatal for the homeless people in Delhi.

The Hindu newspaper reported that at least 106 people, mostly homeless persons, died in January alone last year due to cold conditions, according to the non-governmental organization Centre for Holistic Development (CHD).

This year, the Delhi government has formed 15 rescue teams to bring homeless people to night shelters under the Winter Action Plan, reported The Outlook.

According to the census collected in 2011, Delhi has over 46,000 homeless people out of the city's over 15 million population. Civil society groups, however, believe the actual number is much higher — likely between 150,000 to 200,000.

Pollution causing hazardous conditions

During winter, Delhi is known to suffer from extreme levels of pollution. The fog along with the pollution creates a dangerous cloud of smog, which significantly deteriorates air quality.

Last week, the smog in Delhi caused the cancellation of over 100 flights, while several flights were rerouted, reported The Hindustan Times.

On Friday, NDTV reported that Delhi's Air Quality Index (AQI) had dropped to the "severe" level across much of the area.

The concentration of the fine pollutants spiked to emergency levels over the weekend.

The pollution levels are known to cause health issues, particularly respiratory problems.

The AQI is "nearly 100 times the safe limit set by the World Health Organization. Long term exposure to this micro pollutant can even cause lung cancer," said a report by NDTV.

This report was written in part with material from Reuters news agency.

Edited by: Rebecca Staudenmaier