Question raised in Lok Sabha on Permissible Level of Pollutants, 22/12/2017. Government of India has laid down National Ambient Air Quality standards (NAAQS) for twelve air pollutants, namely, PM10, PM2.5, Carbon Monoxide (CO), Sulphur Dioxide (SO2), Nitrogen Dioxide (NO2), Ammonia (NH3), ground level Ozone (O3), Lead, Arsenic, Nickel, Benzene and Benzo (a) Pyrene. The relevant standards are annexed. The NAAQS helps in assessment of air quality with respect to various pollutants and development of preventive and corrective measures for mitigation.