Aiming to save people from the ill-effects of air pollution, the World Health Organisation (WHO) Wednesday released its revised air quality guidelines for six key pollutants, including extremely hazardous particulate matters — PM2.5 and PM10 — making them more stringent compared with the earlier standards set in 2005. India is currently working on revising its air quality standards that were last updated in 2009. They are set to be released next year.