New Delhi, Sep 12: India being one of the most polluted countries globally, just meeting the international air-quality standards can add "four years" to the average life of people here, while meeting the national standards can add one year, says a study. The study released by the Energy Policy Institute at The University of Chicago (EPIC), which used "Air-Quality-Life Index (AQLI)" to analyse condition in 50 most polluted Indian cities, also found that meeting the international standards can add nine years and national standards can add six years to the life of people of Delhi -- the most polluted city of India. AQLI is a tool which can be used to quantify the number of years that air pollution reduces lifespans around the globe. Based on the particulate matters (PM 2.5), or particles in the air with diameter less than 2.5 mm -- one of the major and common pollutant with direct consequences on the life expectancy, the EPIC used AQLI to compare the pollutant (PM), population and the prescribed standards to derive how much extra years people could live. The standards prescribed by the World Health Organisation (WHO) for PM 2.5 is 10 units, while the Indian standard keeps it at 40 units. However, in the 50 most polluted cities, the pollutant (based on 2015 data) were found to be over nine to two times higher than the WHO standards. There was hardly any data after 2015, a researcher told IANS. Speaking of Delhi alone, the PM 2.5 in 2015 was 98 units. "The AQLI reveals that if India reduced its air pollution to comply with the WHO's air quality standard, its people could live about 4 years longer on average, or a combined more than 4.7 billion life years," the study stated. The data reveals that the greatest gains of controlling the emissions would be seen in the country's largest cities. "The people of Kolkata and Mumbai could live roughly 3.5 years longer if the country met WHO standards," study pointed out. The other cities with a potential considerable improvement in the average life expectancy if WHO norms are followed include (7.6 years), Agra (8.1 years), Patna (6.9 years), Bareilly (7.8 years) and Kanpur (7.2 years). Other major cities are Bengaluru (1.4 years), Chennai (1.7 years), Hyderabad (2.3 years) and Jaipur (4.3 years), if WHO standards are adhered to. "High levels of air pollution are a part of people's lives in India, just as they were in the U.S., England, Japan and other countries in the past. The last several decades have seen tremendous progress in many of these countries, but this progress did not happen by accident, it was the result of policy choices," said Michael Greenstone, the EPIC Director. Greenstone added that as India navigates through the conflicting goals for economic growth and environmental quality, AQLI provides a tool to make the benefits of policies to reduce air pollution concrete. Currently, EPIC India is working with the central and state governments in India to implement world's first first emissions trading programme for particulate pollution. An estimated 4.5 billion people around the world are currently exposed to particulate pollution levels that are at least twice the WHO norms. According to a 2016 report by the World Bank and Institute for Health Metrics and Evaluation, University of Washington, 5.5 million (55 lakh) people die prematurely every year due to household and outdoor air pollution globally, with 60 per cent deaths caused in India and China. In China and India, less than one per cent of the population lives in areas which meet WHO guidelines on air quality termed safe for breathing. The 2016 study showed that India lost 1.4 million lives to air pollution in 2013.