Jim McMahon/Mapman®

The haze in this picture isn’t fog. It’s air pollution in New Delhi, India. That Asian city is the world’s most polluted capital, according to a recent study.

In fact, air pollution is a huge problem across India. The country is home to nearly 1.4 billion people, the second-largest population in the world. It has been developing rapidly in recent decades. As business there has boomed, pollution has increased, a result of emissions from factories and power plants, dust from construction projects, and exhaust from vehicles.

Smoke adds to the problem. It’s created by cities burning trash, farmers setting fire to leftover crops after a harvest, and millions of impoverished people who lack electricity burning fuels like wood to cook.

Air pollution can cause serious health issues, including lung and heart disease. In 2017, 1.2 million Indians died from pollution-related illnesses, a recent study showed.

Last year, India announced a program to reduce air pollution in more than 100 cities. Some environmental experts say that’s a much-needed and encouraging step.