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Fact Sheet: San Joaquin Valley Ozone Reclassification

June 12, 2000

Today's Proposed Action

  • EPA is proposing to reclassify ("bump up") the San Joaquin Valley ozone nonattainment area from serious to severe because the area failed to attain the health-based, 1-hour National Ambient air Quality Standard (NAAQS) for ozone by its Clean air Act deadline of November 15, 1999.
  • The reclassification will assure continued progress toward attainment by restarting the air quality planning process. Although it will give the San Joaquin Valley more time to attain, the area must revise its air quality plan and adopt more stringent controls.
  • In addition to the reclassification, EPA is proposing to find that the San Joaquin Valley air Quality Management District failed to implement a number of measures in its federally-approved air quality plan. If the District does not remedy this failure within 18 month the Valley will be subject to Clean air Act sanctions.
Air Quality in the San Joaquin Valley
  • The reclassification to severe is occurring because air quality in the San Joaquin Valley has not improved as fast as required by the Clean air Act. However, it does not signify that ozone air quality is worsening in the San Joaquin Valley. In general, over the past ten years ozone levels in California have improved greatly, but progress in the San Joaquin Valley has been less significant. Monitoring data from 1997-1999 indicate that thirteen monitoring sites in the San Joaquin Valley nonattainment area are still experiencing unhealthy levels of air quality. These sites are primarily located in the southern part of the Valley.During 1997-1999, the San Joaquin Valley experienced 80 days over the 1-hour ozone standard, ranking fourth behind Los Angeles, California's Southeast Desert, and Houston on the list of the worst regions in the nation.Ground-level ozone is not emitted directly into the air but is formed when nitrogen oxides (NOx) and volatile organic compounds (VOCs) react in the atmosphere. The primary sources of NOx and VOCs in the San Joaquin Valley are cars and trucks, other gasoline and diesel-powered equipment such as farm equipment; consumer and industrial solvents and paints, and oil and gas production.
  • air pollution from the area contributes to air quality problems in several downwind areas, including the North and Central Coast, the Mojave Desert, and the Mountain Counties.
  • The San Joaquin Valley nonattainment area is the largest nonattainment area in California, covering 8 counties and more than 25,000 square miles (16% of California). More than 3 million people currently live in the nonattainment area and this number is growing rapidly.
Health Effects of Ozone
  • Exposure to even low levels of ambient ozone (smog) can cause respiratory symptoms such as a reduction in lung function, chest pain, and cough. Repeated exposure can make people more susceptible to respiratory infection and lung inflammation, and can aggravate pre-existing respiratory diseases.
  • Children are most at risk from exposure to ozone because they are active outside, playing and exercising, during the summertime when ozone levels are at their highest. The elderly and those with respiratory diseases such as asthma are also at high risk.
  • Long-term exposure to ozone can cause irreversible changes in lung structure, which can lead to chronic respiratory illnesses such as emphysema, chronic bronchitis, and/or premature aging of the lungs.
Impact if Today's Proposals are Made Final
  • If the reclassification to severe is finalized, California must submit a new attainment plan within 18 months that demonstrates that the San Joaquin Valley will meet the federal 1-hour ozone standard by November 15, 2005.
  • If the finding of SIP nonimplementation is finalized, the San Joaquin Valley air District will have 18 months to correct the implementation deficiencies by adopting six specific measures committed to in the 1994 California Ozone SIP. Failure to adopt these measures will trigger Clean air Act sanctions.
Public Comment and Further Information
  • EPA encourages the public to comment on these proposed findings. Comments will be accepted for 30 days after the proposal is published in the Federal Register which should happen within one to two weeks.
  • A copy of the notice as well as the supporting documentation is available on Region 9's website: www.epa.gov/region09. For more information, please call John Ungvarsky, U.S. EPA Region 9, air Planning Office at (415) 972-3963.

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