FRIDAY, Feb. 12, 2016 (HealthDay News) -- Every year, poor air quality claims 5.5 million lives prematurely worldwide -- more than half of them in China and India, two of the world's fastest-growing economies, according to new research.

Power and industrial plants release tiny particles into the air that can harm people's health. Particles are also byproducts of burning coal and wood as well as exhaust from cars and other vehicles. Scientists say current efforts to limit these emissions are inadequate, and more needs to be done to prevent an increase in the number of early deaths linked to air pollution over the next two decades.

"Air pollution is the fourth highest risk factor for death globally and by far the leading environmental risk factor for disease," Michael Brauer, a professor in the school of population and public health at the University of British Columbia in Canada, said in a university news release. "Reducing air pollution is an incredibly efficient way to improve the health of a population."

For the study, researchers in the United States, Canada, China and India estimated air pollution levels in China and India and calculated the effects of poor air quality on people's health.

The two countries account for 55 percent of air pollution-related deaths worldwide. In 2013 alone, roughly 1.6 million people in China and 1.4 million in India died as a result of poor air quality, the researchers said.

In China, burning coal is the biggest contributor to air pollution. Outdoor air pollution from coal alone caused an estimated 366,000 deaths in China in 2013, according to Qiao Ma, a doctoral student at Tsinghua University's School of Environment in Beijing.

Ma calculated that in 2030 up to 1.3 million people in China will die early due to poor air quality if the nation adheres to its current air pollution targets and doesn't do more to restrict coal combustion and emissions.

"Our study highlights the urgent need for even more aggressive strategies to reduce emissions from coal and from other sectors," Ma said.

In India, poor air quality is mainly the result of burning wood, dung and other organic materials for cooking and heating. Millions of poor families are routinely exposed to high levels of particulate matter in their homes.

Chandra Venkataraman is a professor of chemical engineering at the Indian Institute of Technology Bombay, in Mumbai. "India needs a three-pronged mitigation approach to address industrial coal burning, open burning for agriculture, and household air pollution sources," she said in the news release.

Over the past 50 years, North America, Western Europe and Japan have dramatically lowered air pollution levels by using cleaner fuels, improving vehicle efficiency, limiting coal burning and placing restrictions on electric power plants and factories.

Dan Greenbaum is president of Health Effects Institute, a Boston-based nonprofit organization. "Having been in charge of designing and implementing strategies to improve air in the United States, I know how difficult it is. Developing countries have a tremendous task in front of them," he said in the news release. "This research helps guide the way by identifying the actions which can best improve public health."

The study findings will be presented Feb. 12 at the annual meeting of the American Association for the Advancement of Science in Washington, D.C. Research presented at meetings is typically considered preliminary because it is not subject to the same scrutiny as that in published journals.

More information

The U.S. Centers for Disease Control and Prevention provides more information on the health effects of air pollution.