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 an Adobe Acrobat PDF.
Joel Schwartz is a visiting fellow at AEI.
