NCPA - National Center for Policy Analysis

Further Ozone Reductions: Are There Benefits?

May 16, 2014

The Environmental Protection Agency (EPA) should not further lower the ozone standard unless there is solid evidence that doing so would actually result in measurable health improvements, say Julie Goodman and Sonia Sax, business and government consultants on air-pollution standards.

The United States has reduced air pollution considerably over the last few decades, with pollution from six common air pollutants having dropped by 72 percent since 1970, according to EPA figures. These reductions, write Goodman and Sax, have improved life expectancy and respiratory health. 

Ozone is a colorless gas regulated by the EPA. It is not emitted directly into the air, rather it is formed when light reacts with other pollutants. Currently, the EPA is evaluating whether or not to make its National Ambient Air Quality Standard for ozone even stricter. Such regulations, according to the EPA, could cost businesses up to $90 billion annually to comply. But will further decreases of the pollutant improve public health?

Currently, the EPA ozone standard is 75 parts per billion, and in 2008, both the EPA and a federal court determined that the level is protective of public health. Now, however, the agency has decided that the standard is inadequate and is seeking to drop the ozone standard to between 60 and 70 parts per billion.

Goodman and Sax write that an "overwhelming" amount of scientific evidence demonstrates that lowering the ozone standard below its current level will not yield any additional health benefits.

  • While the EPA has evaluated most of the scientific studies on ozone exposure and health effects, the agency has not used a "weight-of-evidence" approach to evaluate the studies in a systematic and consistent manner.
  • Most studies that compare ozone to health effects do not take into adequate account the impact of diet and exercise on diseases that might otherwise be attributed to ozone. Without considering these factors, the EPA assumes that ozone is responsible for more health problems than it actually is.
  • A 2006 peer-reviewed paper by Dr. William C. Adams of the University of California did not find a link between ozone exposure and respiratory effects. But the EPA reanalyzed Adams' paper and determined that there was a link between ozone exposure and respiratory illness. Dr. Adams has said that the agency "misinterpreted" his statistics.
  • In its assessment of ozone health risks, the EPA makes a number of "worst-case" assumptions that could not occur simultaneously. This is unrealistic, and it overestimates the ozone risk.
  • The EPA's own models indicate that when human-made ozone sources are decreased, natural ozone increases in some areas. By reducing human-caused ozone, some parts of the country will not be able to meet current standards because of the ozone that forms naturally.

There is no reason to lower the current ozone standard, say Goodman and Sax, unless the agency can actually show that a measurable health improvement would occur as a result.

Source: Julie E. Goodman and Sonia Sax, "The Dubious Benefits of Further Ozone Reductions," Wall Street Journal, May 11, 2014.


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