New Delhi stores have started to sell oxygen as air pollution reaches hazardous levels in the city.

Located in a high-street shopping mall, "Oxygen Pure" offers different flavors of oxygen. Customers can pay 299 to 499 rupees (about 4 to 7 U.S. dollars) to inhale oxygen with scents ranging from mint to lemongrass to cinnamon for 15 minutes.

"I don't know if it's psychological, but it makes me feel good to know I am inhaling pure oxygen, if only for 15 minutes," Lisa Dwivedi from Ukraine told the New York Times.

Earlier this month, Indian authorities declared an "air emergency" after extremely fine particles known as particulate matter (PM2.5) crossed the 530 mark, nearly 100 times the levels recommended by the World Health Organization (WHO).

More than 35 flights were diverted and over 500 delayed due to heavy smog affecting visibility in India's capital New Delhi. Schools were forced to shut down in order to protect the children there. Traffic restrictions were tightened to reduce accident rate.

The Air Quality Index (AQI) at many locations crossed the 999 threshold, the maximum reading that an air monitoring system can record. On November 3, the 24-hour average AQI hovered at 494, the highest in the last three years. In 2016, it stood at 497.

Every year, farmers in the neighboring state of Punjab and Haryana burn paddy straws to clear their fields. The smoke travels to and lingers over the capital, turning it into a "gas chamber." Vehicular emissions and industrial pollution further exacerbate air pollution levels.

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