Pollutants for which specific standards or criteria have not been established. Although some air pollutants are known to be toxic or hazardous, they are released in relatively small quantities or in locations where individual regulation is not required. Others are not yet regulated because data is insufficient to set definite criteria for acceptable ambient levels or control methods. Political and economic interests have also blocked regulatory action. The Clean Air Act Amendments of 1990 required the Environmental Protection Agency (EPA) to establish emission standards for some 189 toxic air pollutants and 250 source categories, thus changing many noncriteria pollutants to criteria ones.

See Also

Criteria Pollutant