Air pollution cuts life expectancy for every man, woman and child on Earth by nearly two years, according to data released Tuesday which experts said showed poor air quality is "the greatest risk to human health".The Air Quality Life Index (AQLI) said that as the world races to find a vaccine to bring the COVID-19 pandemic under control, air pollution would continue to cause billions of people to lead shorter and sicker lives across the globe.The index converts particulate air pollution -- mainly from the burning of fossil fuels -- into its impact on human health.It found that despite significant reductions in particulate matter in China -- once one of the world's most polluted countries -- the overall level of air pollution had stayed.