And the number of premature deaths will continue to climb in the years ahead unless more aggressive measures against pollution are adopted, scientists warned the American Association for the Advancement of Science conference in the US capital.
"Air pollution is the fourth highest risk factor for death globally and by far the leading environmental risk factor for disease," said Michael Brauer, a professor at the University of British Columbia's School of Population and Public Health in Vancouver, Canada.
"Reducing air pollution is an incredibly efficient way to improve the health of a population," said Brauer.
China and India account for 55 per cent of yearly global deaths from air pollution.
More From This Section
Some 1.6 million people died of air pollution in China in 2013, while India saw 1.4 million deaths.
In China, burning coal is the biggest contributor to poor air quality -- and pollution from coal was found to have caused 366,000 deaths in 2013, said Qiao Ma, a PhD student at the School of Environment at Tsinghua University in Beijing.
"Our study highlights the urgent need for even more aggressive strategies to reduce emissions from coal and from other sectors," said Ma.
In India, the main culprit was burning wood, dung and biomass for cooking and heating.
"India needs a three-pronged mitigation approach to address industrial coal burning, open burning for agriculture, and household air pollution sources," said Chandra Venkataraman, professor of Chemical Engineering at the Indian Institute of Technology Bombay, in Mumbai.
According to the World Health Organization (WHO) air quality guidelines, pollution should be restricted to a daily particulate matter of 25 microgrammes per cubic meter.
(Reopens FGN 6)
Unless China adopts more stringent air pollution
standards, limiting coal combustion and particulate emissions from factories and power plants, the report estimated that more than 1 million people would die prematurely by 2030.
And even though China has targets to restrict coal combustion and emissions in the future, it may struggle to bring down the number of deaths because it is acquiring an aging population and these citizens are naturally more susceptible to the illnesses associated with poor air quality.
Chandra Venkataraman, from the Indian Institute of Technology Bombay warned: "Despite proposed emissions control, there is significant growth in the demand for electricity as well as industrial production.
"So, through to 2050, this growth overshadows the emissions controls (in our projections) and will lead to an increase in future air pollutant emissions in 2050 in India," BBC quoted him as saying.
Economic progress in the US, Western Europe and Japan also contributed to high levels of air pollution, according to the report.
Brauer said the statistics should make governments think hard about the scope of their anti-pollution policies.
Medical experts say air pollution leads to heart disease, lung cancer and other respiratory illnesses.
According to the World Health Organisation (WHO) air quality guidelines, pollution should be restricted to a daily particulate matter of 25 microgrammes per cubic meter.
In February, Beijing and New Delhi typically see daily levels at or above 300 microgrammes per cubic meter -- or 1,200 per cent higher than WHO guidelines, researchers said.