The report, described as representing the most detailed outdoor air pollution-related health data ever from the WHO, has said India in 2012 lost over 450,000 people to ischaemic heart disease or strokes and 110,000 to chronic obstructive pulmonary disease attributable to outdoor air pollution.

Among the three million deaths a year linked to outdoor air pollution, the WHO report said, two out of three occur in the South East Asian Region (SEAR) which includes India and 10 other countries. The health impacts of air pollution are derived from epidemiological models connecting air pollution with various health disorders.

"The new WHO model shows countries where the air pollution danger spots are and provides a baseline for monitoring progress," Flavia Bustreo, assistant director general, WHO, said in a release. "Air pollution continues to take a toll on the health of the most vulnerable - women, children, and older adults."

The data relied on the latest comprehensive city-based air pollution data from different countries between 2008 and 2015. The figures for India relate to air quality levels in 2012.

"We prefer to use actual available (air pollution) data rather than make forecasts," Annette PrussUston, an epidemiologist at the public health and environment division of the WHO in Geneva, told The Telegraph. "We hope to have figures for 2015 by early next year."

The calculations for India suggest that exposure to outdoor air pollutants also caused about 26,000 deaths from lung cancer and nearly 40,000 from acute lower respiratory infections. "The numbers combine mortality figures from relevant diseases with air quality, using information from epidemiological studies," a senior WHO official said. "These are calculations based on a model and are not direct measurements."

The WHO South East Asia Region office said the data should be used to strengthen measures against inefficient modes of transport, household fuel, waste burning and coal-fired power plants and other industrial activities that can serve as sources of outdoor air pollution.

"The magnitude of the health impact of air pollution calls for urgent action to prevent these avoidable risks and deaths," Poonam Khetrapal Singh, regional director of the WHO SEAR office, said. "Solutions (should) go beyond simply controlling emissions and should include choices that actively promote health."

The report, which used air quality data from about 3,000 cities and towns in 103 countries, has suggested that more than 80 per cent of people living in urban areas that monitor air quality are exposed to pollution levels that exceed the WHO limits.

The analysis has found that 98 per cent of cities in low and middle-income countries with more than 100,000 residents do not meet WHO air quality standards. In high-income countries, 56 per cent of cities with similar large populations do not meet the standards.