Air pollution could cause 6-9 million premature deaths by 2060, with India and China facing threat of maximum number of such mortalities, according to an OECD report.

The menace is also likely to cost 1% of the global GDP, around $2.6 trillion annually, in terms of sick days, medical bills and reduced agricultural output, says the report by the Organisation for Economic Co-operation and Development (OECD).

'The Economic Consequences of Air Pollution' report said the outdoor air pollution caused more than 3 million premature deaths in 2010.

"Outdoor air pollution could cause 6 to 9 million premature deaths a year by 2060 and cost 1% of global GDP around $2.6 trillion annually as a result of sick days, medical bills and reduced agricultural output, unless action is taken," the report said.

The projections imply a doubling, or even tripling, of premature deaths from dirty air or one premature death every four or five seconds by 2060, it added.

"The biggest rise in mortality rates from air pollution are forecast in India, China, Korea and Central Asian countries like Uzbekistan, where rising population and congested cities mean more people are exposed to power plant emissions and traffic exhaust," it said.

Premature death rates are forecast to be up to three times higher in 2060 than in 2010 in China and up to four times higher in India, it said.

The report said a large number of deaths occur in densely populated regions with high concentrations of PM2.5 and ozone, especially China and India, and in regions with aging populations, such as China and Eastern Europe.

However, death rates are seen stabilising in the United States and falling in much of Western Europe due to efforts to move to cleaner energy and transport.

Talking about projected GDP losses, the report said it will be biggest in China, Russia, India, Korea and countries in Eastern Europe and the Caspian region, as health costs and lower labour productivity hit output.

"Poor air quality will hit China's economy harder than India's because differences in household savings rates and demographics mean the knock-on effects of lower productivity and increased health spending on the rest of the Chinese economy will be much larger," OECD said.

One key difference between the two countries is the age structure of the population: India has a much younger population, while aging is projected to become a more severe problem in China, as per the report.