With India's capital engulfed in choking pollution, someone has sniffed an opportunity. A bar offering a wide variety of purified oxygen to clients with different aromas via nasal cannulas has become popular among middle-aged and elderly residents in New Delhi. /VCG Photo

The bar offers 15 minute sessions that start at 4 U.S. dollars and go up to 7 U.S. dollars. /VCG Photo

With the air quality index (AQI) touching 527, which is above "emergency" levels, country's capital topped the list of the most polluted cities in the world, November 15, 2019. /VCG Photo

Three of the top 10 polluted cities fall in India, including Delhi, Kolkata and Mumbai. So air pollution is not necessarily a problem specific to northern India although Delhi's pollution is double that of Kolkata, according to Gulf News. /VCG Photo