On 17 December 2014, the US Environmental Protection Agency (EPA) released a Proposed Rule to revise the National Ambient Air Quality Standards (NAAQS) for ozone (79 Fed. Reg. 75234). This paper, prepared by Dr. Anne E. Smith and Dr. Garrett Glasgow, includes comments on technical issues associated with epidemiologically‐based health risk estimates that the Proposed Rule indicates may play a role in the Administrator’s ozone NAAQS determination. The health risk estimates described in the Proposed Rule are documented in EPA’s Heath Risk and Exposure Assessment (HREA) document (EPA, 2014a).

The paper also examines how the Proposed Rule is interpreting certain of those HREA estimates as well as inconsistencies between the RIA’s representation of the Proposed Rule’s potential health benefits and the way that the Proposed Rule is being justified.