Amendments to the List of Hazardous Air Pollutants (HAP) of Section 112(b) of the Clean Air Act (CAA)

Summary

The list of HAP is a list of organic and inorganic substances that have been identified as hazardous air pollutants to be regulated under CAA section 112. The initial list of HAP, which can be found in CAA section 112(b)(1), was identified by Congress in the 1990 CAA. The substances listed as HAP have been associated with a wide variety of adverse health effects, including cancer, neurological effects, reproductive effects, and developmental effects. The health effects associated with various HAP differ depending on the toxicity of the individual HAP and the particular circumstances of exposure, such as the amount of chemical present, the length of time a person is exposed, and the stage of life at which the person is exposed. CAA section 112(c) directs the EPA to first identify and list source categories that emit HAP and then to set emission standards for those listed source categories under CAA section 112(d). Standards promulgated under CAA section 112(d) are commonly referred to as National Emission Standards for Hazardous Air Pollutants (NESHAP).  

Section 112(b)(3)(A) of the CAA specifies that any person may petition the Administrator to modify the list of HAP contained in CAA section 112(b)(1) by adding or deleting a substance. The Administrator must grant or deny such a petition to delete a HAP within 18 months after receipt of a complete petition. Section 112(b)(3)(C) sets out the substantive criteria for granting a petition to delete a HAP from the CAA section 112(b)(1) HAP list under CAA section 112(b)(3)(A). 

HAP Listing History

HAP Delisting History

Note: Hydrogen Sulfide was added to the original list inadvertently but removed by Congress with Presidential approval in 1991  

Complete Petitions Received