Ground-level ozone, a major component of smog, is a persistent air quality problem in several areas of the country. The recently enacted Border Smog Reduction Act of 1998 addresses one aspect of the problem, which involves reducing ozone-causing chemicals from certain foreign-registered vehicles. The act currently applies only to the San Diego metropolitan area and amends the Clean Air Act to prohibit certain foreign-registered, noncommercial vehicles from entering the area more than twice a month unless they have complied with California's inspection and maintenance requirements. While the Border Smog Reduction Act addresses emissions from certain passenger vehicles, it does not address those from commercial vehicles, such as trucks, which are also a source of ozone-causing chemicals. The effect of increased commercial vehicle traffic on air quality has been of particular concern since the North American Free Trade Agreement (NAFTA) was implemented in January 1994. The Border Smog Reduction Act required the General Accounting Office (GAO) to study the act's potential impact. The GAO focused on measured ozone levels and the impact of NAFTA on ozone in the San Diego area. Specifically, they determined (1) what estimates were available of the act's potential impact on ozone-causing chemicals in the San Diego area and (2) trends in commercial border traffic and ozone levels in the San Diego area before and after NAFTA was implemented. Briefly, results of the study indicated the following: The California Air Resources Board, a state agency that regulates air quality, estimated that the Border Smog Reduction Act would reduce ozone-causing chemicals in San Diego County by less than 0.5% annually. The act's impact is difficult to estimate because data are not available on the number and condition of foreign-registered vehicles entering the United States and a variety of factors influence measured ozone levels. The trend in commercial truck crossings into the United States from Mexico was generally upward both before and after NAFTA was implemented in January 1994. At the same time, the trend in measured ozone levels in the San Diego area was generally downward. Because a number of factors affect measured ozone levels, it is difficult to isolate the impact of a single factor, such as commercial truck traffic.


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Media Info

  • Features: Figures;
  • Pagination: 11 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00778414
  • Record Type: Publication
  • Report/Paper Numbers: GAO/RCED-99-212
  • Files: TRIS
  • Created Date: Nov 16 1999 12:00AM