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Statement of Need: CAA section 112(f)(2) requires us to determine for source categories subject to certain CAA section 112(d) standards whether the emissions limitations provide an ample margin of safety to protect public health. If the MACT standards for HAP “classified as a known, probable, or possible human carcinogen do not reduce lifetime excess cancer risks to the individual most exposed to emissions from a source in the category or subcategory to less than 1-in-1 million,” EPA must promulgate residual risk standards for the source category (or subcategory), as necessary, to provide an ample margin of safety to protect public health. EPA must also adopt more stringent standards, if necessary, to prevent an adverse environmental effect, “Adverse environmental effect” is defined in CAA section 112(a)(7) as any significant and widespread adverse effect which may be reasonably anticipated to wildlife, aquatic life, or natural resources, including adverse impacts on populations of endangered or threatened species or significant degradation of environmental quality over broad areas. but must consider cost, energy, safety, and other relevant factors in doing so. This residual risk review is due 8 years after MACT standard compliance date. EPA is also required to review and revise the MACT standards every 8 years with regard to practices, processes and control technologies according to Section 112(d)(6) of the CAA.

Summary of the Legal Basis: Clean Air Act Sections 112(f)(2) and 112(d)(6).

Alternatives: Alternatives are developed for residual risk to evaluate ample margin of safety or if risk is unaccetable. Alternatives are developed for technology review if there have been significant advances in practices, processes and control technologies. For the Printing and Publishing MACT, risks were acceptable and an ample margin of safety was achieved, and no significant technological advances were identified. Therefore, no alternatives were evaluated. For the other eight source categories in RTR Group 2A, alternatives were considered; none was cost-effective relative to the associated reduction in risk.

Anticipated Costs and Benefits: No revisions to the MACT standards were proposed; therefore, there are no associated costs or emissions reductions.

Risks: The risk assessment found that after application of the MACT standards the chronic cancer risks are below 100-in-1 million, which is acceptable, and additional controls were not cost-effective; therefore, the MACT standards provide an ample margin of safety to protect public health and no further cancer risk reduction was required. The analysis also found that non-cancer and acute risks to humans, as well as ecological risks from these facilities, were low and that no further controls were warranted.