Five Reasons the Ozone Standard Should Be Strengthened

I’ve talked here, here, and here about the EPA National Ambient Air Quality Standards (NAAQS) update to the ozone standard. Today is the last day of the EPA’s public comment period (to which I have submitted a comment). So I thought it would be a good time to do a quick review of the top five reasons the ozone standard should be strengthened in order to provide an adequate margin of safety for the most vulnerable populations—including the elderly, children, and those with lung diseases.

Ozone pollution causes health impacts, including respiratory problems, especially for vulnerable populations such as children, the elderly, and those with lung diseases like asthma. Photo: Gretchen Goldman

The Science. As part of the update to the ozone standard, EPA conducts the Integrated Science Assessment (ISA). The 1,251-page document is produced by EPA scientists and surveys the current scientific literature on ozone (including, I am proud to say, one of my own papers). The peer-reviewed document finds several “causal” and “likely causal” relationships between ozone pollution and health effects. Of note, the report identifies “a very large amount of evidence spanning several decades [that] supports a relationship between exposure to O₃ and a broad range of respiratory effects.” In addition, the report finds associations between ozone and short-term cardiovascular effects and total mortality, along with long-term respiratory effects.
The Science. As I’ve written before, the Clean Air Science Advisory Committee (CASAC), or the group of external independent subject-matter experts that EPA uses to provide scientific recommendations for the standard, came to the conclusion that the standard should be tightened. In its letter to the EPA administrator, the science advisors recommended a range of 60-70 ppb for the standard. In addition, the committee concluded that although 70 ppb was included in its recommended range, such a standard would not provide an “adequate margin of safety,” as the Clean Air Act mandates. The committee goes on to note that with a 70-ppb standard there is “substantial scientific evidence of adverse effects … including decrease in lung function, increase in respiratory symptoms, and increase in airway inflammation.”
The Science. The Ozone Review Panel is an additional set of external independent experts that works with CASAC to discuss the state of the science and review the ISA. These experts are brought in to provide additional expertise specific to ozone. This panel largely concurred with lowering the standard to something in the 60 to 70 ppb range as well, noting that a standard below 70 ppb would be more protective of public health.
The Science—including the old science. It’s worth reiterating that the above voices recommending a lower standard are joining those from the previous years. In fact, CASAC first proposed that the ozone standard be in the 60 to 70 ppb range back in 2007. (2007!) To put that in perspective, in 2007 I still used a PalmPilot and hadn’t heard of Taylor Swift. Our technology and music have evolved since then, and so too has ozone science.
The Science. The bottom line and the reason that these top five reasons are all one reason is precisely that. The law requires setting the ozone standard based on science and science alone. The administration must set a standard that is protective of public health with an adequate margin of safety and cannot legally consider economic arguments. This latter point is notable given the degree of effort that some have been putting into making economic arguments against lowering the standard. It sounds like some might need to review these five reasons—not cost arguments—that the standard needs to be lowered.

If you feel so inclined, please join me in supporting a science-based ozone standard by submitting a public comment here.