Pedestrians gathered as smog enveloped the Red Fort in New Delhi in 2009.
Pedestrians gathered as smog enveloped the Red Fort in New Delhi in 2009. © Raveendran/Agence France-Presse — Getty Images

It is hard to imagine winter in New Delhi without fog, but 60 years ago it was a rather rare weather phenomenon in the city.

Since last Monday, India’s national capital has been grappling with dense fog. Several flights have been cancelled this week, and at least 115 trains were delayed on Thursday alone, due to dangerously low visibility. Such weather conditions—and the ensuing turmoil—is likely to continue for the next few weeks.

But historic data from the 1950s shows that Delhi of yore was blissfully spared such a prolonged winter chaos.

In fact, in the year 1951 only one fog day was reported during winter months (Dec to Feb). The year 2013 had 74 such days during the same period, and 2014—excluding December—has already seen 54 fog days, according to data sourced from Centre for Atmospheric Sciences at Indian Institute of Technology (IIT) Delhi.

People made a fire in New Delhi to keep warm on Friday, one of many sources of pollution that makes the city’s air among the world’s worst.
People made a fire in New Delhi to keep warm on Friday, one of many sources of pollution that makes the city’s air among the world’s worst. - “It’s always puzzled me that the focus is always on China and not India,” said Dr. Angel Hsu, director of the environmental performance measurement program at the Yale Center for Environmental Law and Policy. “China has realized that it can’t hide behind its usual opacity, whereas India gets no pressure to release better data. So there simply isn’t good public data on India like there is for China.”Experts have long known that India’s air is among the worst in the world. A recent analysis by Yale researchers found that seven of the 10 countries with the worst air pollution exposures are in South Asia. And evidence is mounting that Indians pay a higher price for air pollution than almost anyone. A recent study showed that Indians have the world’s weakest lungs, with far less capacity than Chinese lungs. Researchers are beginning to suspect that India’s unusual mix of polluted air, poor sanitation and contaminated water may make the country among the most dangerous in the world for lungs. © Sami Siva for The New York Times