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China has long been the world's worst when it comes to air pollution, but a new study suggests that India's trouble is now on par with China's and poised to exceed it.

The study from the Health Effects Institute and Institute of Health Metrics and Evaluation finds that air pollution was responsible for more than 4.2 million deaths in 2015—making it the fifth-leading cause of death worldwide—including 1.1 million each in China and India, reports the New York Times.

But whereas China has been working to prevent such deaths, causing its number to level out, the number of deaths linked to airborne particles known as PM2.5s jumped 50% in India from 1990 to 2015, per AFP.

Rapid industrialization with a focus on coal production, population growth, and an aging public more vulnerable to pollution have created "the perfect storm for India," says a researcher.

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Yet a rep for the Public Health Foundation of India says the government isn't taking action. Last week, a government official there said "there is no conclusive data available" linking pollution and mortality, per Reuters.

The study does offer hope, though: It finds the 20% increase in deaths from air pollution worldwide since 1990 was slower than the rate of population increase.

Pollution also improved in Europe and the US with environmental regulations. That said, 258,000 Europeans and 88,000 Americans are still at risk of premature death due to air pollution, the study says.

(Some of the dirtiest air in the US can be found at the North Pole.)

This article originally appeared on Newser: China Has Deadliest Air Pollution? Maybe Not