NEW DELHI: The National Capital Region has turned into a gas chamber ahead of Diwali with a thick blanket of smog engulfing the skies and placing air quality in "emergency" or "beyond-severe" category. The air quality is expected to deteriorate to 'severe plus emergency' category after Diwali even if "partial toxic crackers" are burned compared to last year, a government-run agency has said. In 2016 and 2017, schools were shut down for a few days under similar conditions.

Tourists and foreigners are having tough times and said were forced to visit hospitals to seek treatment for breathlessness, allergy and irritation. Some even are cutting short their trips citing health concerns as even pollution masks were proving ineffective.

Emily, from Amsterdam, said she was cutting short her visit to Delhi due to the deteriorating air quality.

"I wanted to spend the Christmas with my friends but then the air quality is so bad that I have decided not to stay here anymore. I will rather go to Kerala and spend the rest of my holidays there," she told PTI.

Sonia Aggarwal, who is in Delhi with her family to celebrate Diwali, said she had to take her daughter to hospital after she complained of breathlessness.

"Doctors have advised my daughter to use inhalers for the time being. She took ill because of the bad weather conditions. We are concerned about her well-being," Aggarwal, a mother of two, told the news agency.

Anthony, from Cork city in Ireland, said he used to hear that winter is the best time to visit India but now he feels he should have chosen Bhutan or Nepal for vacation.

Hoteliers too complained that they were suffering losses as tourists were leaving the city.

"The business has started falling like every year at this time as several tourists are cancelling their stay due to the air quality deteriorating to hazardous levels. Those who were scheduled to visit Delhi have postponed their trip after reading reports of pollution; they are preferring other destinations," said Harish Sharma, manager of a hotel in Old Delhi.