India’s national capital region (NCR) emerged as the most polluted region in the world in 2018, according to data compiled in a report. Fifteen of the 20 most polluted cities in the world are in India, with Gurugram, Ghaziabad, Faridabad, Noida and Bhiwadi in the top six, says the study.

The latest data compiled in the IQAir AirVisual 2018 World Air Quality Report and interactive world’s most polluted cities ranking, prepared in collaboration with Greenpeace Southeast Asia, reveals the state of particulate matter (PM2.5) pollution last year. Out of the 20 most polluted cities in the world, 18 are in India, Pakistan and Bangladesh, the report said.

At a country level, weighted by population, Bangladesh emerges as the most polluted country on average, closely followed by Pakistan and India, with Afghanistan and Mongolia also in the top 10.

India has 15 out of the 20 most polluted cities in the world, with Gurugram and Ghaziabad being the most polluted cities and Delhi on the 10th spot, it said.

Out of the more than 3,000 cities included in the study, 64 per cent exceeded the WHO’s annual exposure guideline for fine particulate matter, also known as PM2.5. Hundred per cent of measured cities within West Asia and Africa exceeded this guideline, while 99 per cent of cities in South Asia, 95 per cent of cities in Southeast Asia, and 89 per cent of cities in East Asia also exceed this target.

China’s capital Beijing - once among the most polluted cities in the world - ranked 122nd in the list of the most polluted cities last year based on PM2.5 data, but is still at least five times more polluted than the WHO annual safety limits of 10 g/m3.

Air pollution is the greatest environmental risk to health today, estimated to contribute to 7 million premature deaths every year, the report said. Polluted air presents the world’s fourth leading contributing cause of early deaths, and burdens the global economy with an estimated annual cost of $225 billion.

The report also identified some of the major sources or causes of ambient air pollution. “Industries, households, cars and trucks emit complex mixtures of air pollutants, many of which are harmful to health. Of all of these pollutants, fine particulate matter has the greatest effect on human health. Most fine particulate matter comes from fuel combustion, both from mobile sources such as vehicles and from stationary sources such as power plants, industry, households, agriculture or biomass burning,” it said.