In November 2014, the US Environmental Protection Agency (EPA) proposed a rule that would lower the eight-hour primary and secondary ozone standards from the current level of 75 parts per billion to a level between 70 and 65 parts per billion. The proposed rule has undergone a few public hearings and is being discussed inside the House of Representatives’ Subcommittee on Energy and Power. By court order, the EPA is directed to publish the final rule on or before October 1, 2015.

Twenty-six states, including Texas, currently oppose the proposed rule. On March 16, 2015, 11 governors wrote a joint letter to the EPA’s administrator saying the following: “The proposed NAAQS [National Ambient Air Quality Standard] is so extreme that even some of our pristine national parks may not be able to satisfy it. It goes without saying that most cities and counties have no chance of attaining this standard.”

TCEQ’s toxicology Section studied EPA’s Health Risk Exposure Assessment of Ozone (HREA), which is the document used to support EPA’s proposed ozone standard. It also pulled from other scientific reports and studies to support its opposition to this proposed rule. TCEQ demonstrated an inverse relationship between ambient ozone concentrations and asthma-related hospitalizations

TCEQ also highlighted an unexpected finding in the HREA that was buried within the 500 page document: EPA’s model predicted an increase in premature mortality for several of the cities studied if ambient ozone concentration was lowered.

TCEQ also noted that EPA’s HREA lacked the now standard Weight of Evidence evaluation which is a technique used in scientific literature to take into account different kinds of scientific evidence when the goal is to assess the validity of a causal hypothesis like EPA’s claim: “Ozone causes decreased lung function.”

TCEQ concluded that EPA neither adequately evaluated the scientific evidence nor provided adequate justification for a lower standard. If the Clean Air Act prohibits EPA from considering the cost of setting the standard, then it is important that the EPA rely on solid scientific arguments leaving little doubt that a lower standard will clearly result in health benefits. Otherwise, the decision to lower the standard will be based more on politics and other forces that will not benefit the public and will cost billions.