2005 Southland Smog Season One of the
Cleanest on Record

Nov. 18, 2005

This year’s smog season rivaled 2004 as one of the cleanest on record, with the fewest days ever recorded for violations of the tough federal 8-hour ozone health standard.

“Recent air quality trends suggest that we are on the right track in continuing to make progress toward achieving clean air for Southland residents,” said Barry Wallerstein, executive officer for the South Coast Air Quality Management District.

“However, we need to be mindful that further air quality improvements will require new aggressive emission reduction programs, especially for sources that historically have been under-regulated, including locomotives, ocean-going ships and other equipment at the ports of Los Angeles and Long Beach.”

Air quality during this year’s smog season exceeded the federal 8-hour ozone health standard on 84 days, compared to 90 days in 2004.  The peak 8-hour concentration this year was 0.145 parts per million (ppm), very close to last year’s 0.148 peak.  The one-hour ozone average, no longer a regulatory standard but still an important air quality benchmark, was exceeded on 30 days this year, a slight increase from 28 days last year.

From year to year, weather plays a major role in smog levels, and for that reason air quality trends need to be examined over a period of several years to judge progress toward clean air goals.  Following near-record rainfall last winter and spring, the start of this year’s smog season featured cooler-than-normal weather conducive to relatively cleaner air.  Summer weather returned to normal in July and August with several hot, stagnant periods favorable to smog formation.

Comparison to Other Areas

Southern California has had the worst overall air pollution problem in the nation since World War II and arguably still bears that burden today.  However, two other areas of the country – Houston and the San Joaquin Valley – also have severe ozone problems and periodically surpass the Southland in the number of ozone violations.

This year, Southern California had the worst air quality in the nation for 8-hour ozone values, while Houston had the most severe ozone air pollution for one-hour ozone levels. In 2003 and 2004, the San Joaquin Valley had the worst air quality in the nation for 8-hour ozone violations.

The U.S. Environmental Protection Agency recently enacted an eight-hour ozone standard, exceeded when ozone levels rise above 0.08 parts per million (ppm) during an eight-hour average.  It is tougher and more health protective than the one-hour standard, exceeded when ozone levels are above 0.12 ppm during a one-hour average.  Southern California must meet the eight-hour standard by 2021.

Ozone Air Quality -- Comparison to Other Areas
2003-2005*

Source:  South Coast AQMD

Ground-level ozone, a colorless and pungent gas, damages lung cells and may be linked to permanent lung damage. (Ozone in the stratospheric “ozone layer,” several miles above Earth, protects people from the sun’s harmful radiation.)  Ground-level ozone can cause short-term effects including chest pain, coughing, and nose and throat irritation, and is linked to increased symptoms for those with asthma and bronchitis.

Smog season officially starts on May 1 and ends on Oct. 31.  AQMD has monitored ozone at more than 30 stations across a four-county network since 1976.

AQMD is the air pollution control agency for Orange County and major portions of Los Angeles, San Bernardino and Riverside counties.

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