Final Rule Signed re Revisions to NESHAP Subpart W of 40 Part 61

On December 20, 2016, U.S. Environmental Protection Agency (EPA) Administrator Gina McCarthy signed a final rule that revised “National Emission Standards for Radon Emissions from Operating Mill Tailings,” Subpart W of 40 CFR Part 61, which was last issued in 1989.

Subpart W is a radon emission standard for operating uranium mill tailings.  (Tailings are the remaining portion of a metal-bearing ore after some or all of a metal, such as uranium, has been extracted.)  In accordance with the Clean Air Act Amendments of 1990, EPA formed a work group to review the standard.

Interested stakeholders can view a pre-publication copy of the final rule and a fact sheet at


EPA’s mission is to protect human health and natural resources from pollution.  The Agency sets limits on the amount of radioactivity that can be released into the environment.

Based on a review and assessment of available, effective and affordable pollution control approaches, EPA determined that the revised Subpart W standards protect human health and the environment by limiting the amount of radon emitted by uranium byproduct material or tailings being managed at uranium recovery facilities.


EPA limits emissions of hazardous air pollutants under the authority of the Clean Air Act.  As found in 40 CFR Part 61, EPA’s National Emission Standards for Hazardous Air Pollutants (NESHAP) set limits on hazardous air pollutants from different activities and facilities.  Subpart W of 40 CFR Part 61, National Emission Standards for Operating Mill Tailings, limits radon emissions from uranium byproduct material or tailings at operating uranium recovery facilities.  EPA originally issued Subpart W in December 1989, as found at 54 Federal Register 51,703, and then updated Subpart W in 2016.

The Clean Air Act Amendments of 1990 required EPA to review and, if appropriate, revise the standards in Subpart W.  After completing the review and soliciting public comment, EPA concluded that revisions were needed to clarify definitions and to be more specific about what kind of uranium byproduct material or tailings management is subject to the standard.  EPA also concluded that requirements for generally available control technology (GACT) management practices are an appropriate means to control radon emissions from uranium byproduct material or tailings.  GACT consists of commercially available methods, practices and techniques for operation and maintenance of emissions control systems.

Although EPA enforces the Clean Air Act at Subpart W, the U.S. Nuclear Regulatory Commission (NRC) has regulatory responsibility for licensing and operation of uranium extraction facilities and other commercial facilities that use radioactive materials.  The revised Subpart W does not relieve the owner or operator of the uranium recovery facility of the monitoring and maintenance requirements specified in the operating license issued by the NRC or its Agreement State.

For additional information, please contact Dan Schultheisz, Office of Radiation and Indoor Air, Radiation Protection Division, U.S. Environmental Protection Agency, at (202) 443- 9290 or at  Interested stakeholders may also access the EPA website to find information related to this rulemaking at