More than 5.5 million people die annually due to both outdoor and household air pollution, making it one of the leading global risk factors for disease, according to new research.

The research, presented at the annual American Association for the Advancement of Science (AAAS) meeting Friday, suggests that the number of deaths tied to air pollution will continue to rise in the coming decades barring tougher efforts to slow emissions that harm human health.

China and India, home to the world’s two fastest growing economies, will likely bear the brunt of those effects. More than half of the deaths caused by air pollution around the world occur in those two countries, according to the research. Brazil, Pakistan and Japan also rank among other countries that have experienced increases in pollution deaths in recent decades.

A number of sources including power plants, heavy industry and vehicles contribute to outdoor air pollution around the globe. Sources of household air pollution include the use of coal, wood and charcoal to cook and heat homes in less developed countries.

The researchers’ findings will hardly come as a surprise to those who study air pollution. Previous research has shown that outdoor air pollution causes more than 3 million deaths annually and suggested that the figure could double by 2050. Another study suggested that air pollution causes 1.6 million premature deaths annually in China alone.

Policymakers across the globe have responded to air pollution with a slew of new regulations, many of which focus on curbing pollution from coal. China halted approval of new coal mines for three years at the end of 2015 and has issued stringent requirements along the lines of those in the U.S. for new coal fired power plants. Cities in China have also developed warning systems to get cars off the streets and halt industrial pollution during periods of intense smog. But even these policies may still be met by increases in mortality as aging populations are increasingly susceptible to the problems associated with pollution.

“China might move in the right direction in terms of air pollution, but it’s going to have continue revisiting [policies] just like the U.S. and Europe,” said Dan Greenbaum, president of Health Effects Institute, which sponsored the research.

And, while premature deaths attributable to pollution in the U.S. and Europe have declined in recent decades, cities in the West have still taken steps to reduce pollution. Air pollution kills more than 200,000 in Europe and nearly 80,000 in the U.S. each year, according to the research.

The benefits of addressing air pollution extend beyond the people who experience the health effects of poor air directly. Many of the same pollutants that clog human lungs also contribute to climate change.

“One of the unique things about air pollution is that you can’t run, you can’t hide from it,” said study researcher Michael Brauer, a professor at the University of British Columbia, in a video accompanying the presentation. “But we know that if you improve air quality, everybody benefits from it.”

Get our Health Newsletter. Sign up to receive the latest health and science news, plus answers to wellness questions and expert tips. Please enter a valid email address. Sign Up Now Check the box if you do not wish to receive promotional offers via email from TIME. You can unsubscribe at any time. By signing up you are agreeing to our Terms of Use and Privacy Policy . This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. Thank you! For your security, we've sent a confirmation email to the address you entered. Click the link to confirm your subscription and begin receiving our newsletters. If you don't get the confirmation within 10 minutes, please check your spam folder.

Write to Justin Worland at justin.worland@time.com.