Introduction

On July 11, 2007, the Environmental Protection Agency (EPA) proposed a more stringent national standard for ambient ozone levels (the "Proposed Rule").1 EPA is considering a new standard somewhere in the range of 0.060 to 0.080 parts per million (ppm), with a preferred value in the range of 0.070-0.075 ppm.

EPA relies mainly on two major types of human health effects studies in an attempt to justify a more stringent ozone standard: observational epidemiology studies and controlled laboratory studies with human volunteers. According to EPA, both types of studies provide evidence that ozone has adverse health effects at levels below the current 8-hour ozone standard of 0.085 ppm. EPA is mistaken. In its proposed rule, presentations, criteria documents, staff reports, and other paperwork, EPA creates a misleading appearance that there is a vast body of robust and consistent evidence for its claims of harm from low-level ozone. As I show below, the weight of the evidence suggests just the opposite. The current 8-hour ozone standard is more than stringent enough to protect Americans' health "with an adequate margin of safety."

The full text of this testimony is available here as a PDF.

Joel Schwartz is a visiting fellow at AEI.