The world’s most polluted capital cities have been revealed, and Delhi has been exposed as the worst. Residents in India’s capital city were exposed to more than ten times the safe amount of air pollution on an average day, a study has shown. Dhaka, in Bangladesh, ranked second-worst with ten times the safe limit while Kabul, in Afghanistan, ranked third, with six times the same limit. New Zealand’s capital city of Wellington is the least polluted, falling well under WHO guidelines for safe amounts of air pollution. The report was published by IQ AirVisual and Greenpeace which calculated the average amount of PM2.5 air pollution in each city. Researchers focused on the amount of PM2.5s because they are the smallest and most harmful type of airborne particles which can lodge deep in the lungs. The study’s authors wrote that poor air quality “is the greatest environmental risk to health and contributes to an estimated 7 million deaths each year.” Yeb Sano, executive director of Greenpeace Southeast Asia, said, “Air pollution steals our livelihoods and our futures, but we can change that. In addition to human lives lost, there’s an estimated global cost of $225 billion in lost labour, and trillions in medical costs.” In total, authors found that 64 per cent of world cities exceeded WHO guidelines, with 100 per cent of measured cities in the Middle East and Africa breaking the limit. Meanwhile 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 exceeded this target. Gurugram, in northern India, was found to have the worst air of any city in the world, with Faisalabad in Pakistan in third.