Air quality standards provide a legal framework for air pollution control. An air quality standard is a description of a level of air quality that is adopted by a regulatory authority as enforceable. The basis of development of standard should be to provide a rational for protecting public health from adverse effects of air pollutants, to eliminate or reduce exposure to hazardous air pollutants, and to guide national and local authorities in their air quality management decisions. To provide the legislative support for air quality protection, the Central Pollution Control Board (CPCB) recognized the need to review the air quality criteria/standards. For this purpose, CPCB sponsored a project to the Indian Institute of Technology, Kanpur to review air quality criteria and propose revised air quality standards with recent scientific knowledge of air pollution, their exposure and health effects.