The 2019 World Air Quality Report published by IQAir AirVisual on Tuesday has ranked Indian metropolises as some of the world’s worst polluted with smoggiest urban areas, accounting for 14 of the top 20.

Several Chinese cities, including Beijing, however, have dramatically improved their air quality in recent years. Once infamous for its toxic air Beijing has reduced smog levels and dropped down a list of the world’s most polluted cities, falling to 199 from 84 three years before.

New Delhi’s air quality has fallen from where it was five years ago, rising to the fifth-worst spot globally and making it by far the world’s most polluted major city, the report said.

With climate activists and scientists urging world leaders to reduce carbon emissions to prevent irreversible destruction to the planet’s climate, India, China, and other Asian countries remain major contributors to toxic air. Multiple factors ranging from crowded cities, vehicular exhaust, coal-fired power plants, agricultural burning, and industrial emissions have contributed to this problem.

The World Health Organization estimates that dirty air kills around 7 million people each year, while the World Bank says it drains the global economy of $5 trillion annually.