The document discusses air quality parameters and air pollution. It outlines that the Central Pollution Control Board establishes air quality standards for India and coordinates with state pollution control boards. An air quality index is used to communicate current and forecast air pollution levels based on measurements of 8 pollutants. Examples of current air quality index levels are provided for several Indian cities. Metrics for assessing air pollution levels internationally and factors used to evaluate air quality are also described. Standards for air quality under clean air acts in the US and EU are briefly outlined.