54,000 people died in Delhi due to air pollution caused by hazardous PM2.5 particulate matter New Delhi: Air pollution caused by hazardous PM2.5 fine particulate matter led to the death of 54,000 people in Delhi last year where pollution levels remained almost six times above the prescribed WHO limits, according to a new study. According to a Greenpeace Southeast Asia analysis of IQAir data, 1800 deaths per million were estimated due to PM2.5 air pollution in Delhi. "The PM2.5 air pollution claimed approximately 54,000 lives in India's national capital in 2020," the study said. PM2.5 refers to fine particulate matter smaller than 2.5 micrometers in diameter. Exposure to PM2.5 is considered the most important environmental risk factor for deaths globally, and was attributed to 4.2 million premature deaths in 2015, the study said.