83668d83_The_Legislative_Framework__Description
[Instrument] objectives / standards Air Quality Objectives and Standards [Description] 
(air quality) levels for specific pollutants that are determined to be necessary to protect human health and/or the environment usually include a numeric pollutant concentration, averaging time, rules or guidance on sampling methodology, and how the objectives or standards are to be applied may also be referred to as "air quality criteria" or "guidelines"
The Legislative Framework
Description