Although Southland residents experienced more smoggy days this year than last, air quality trends continued to show improvement in some areas.

"We are on the right track with our air pollution control program," said Barry Wallerstein, executive officer of the South Coast Air Quality Management District. "This year’s numbers show that we need to redouble our efforts, particularly in reducing pollution from cars, trucks and other mobile sources, which are responsible for more than 70 percent of ozone-forming emissions."

The federal one-hour ozone health standard of 0.12 parts per million was exceeded on 49 days this year, up from 36 last year.

"From year to year, weather plays a major role in ozone smog formation," said Joe Cassmassi, AQMD’s senior meteorologist. "This summer’s weather – along with several major wildfires – was extremely conducive to smog formation."

This summer’s meteorology featured many days with unusually strong atmospheric temperature inversions – a condition that traps smog relatively low to the ground, Cassmassi said. A stronger than usual onshore sea breeze this summer also helped keep the inversions in place. Sticky monsoon weather typical of late July and early August, which tends to help disperse smog, didn’t happen this summer. And wildfires from Santa Clarita to the San Gabriel and San Bernardino mountains produced enormous quantities of ozone-forming gases.

In spite of unfavorable conditions, several trends this year show continuing progress in improving air quality:

• The Southland’s peak ozone level this year – 0.169 parts per million, recorded on July 10 in the Santa Clarita Valley, was the lowest monitored since records first were kept in the mid-1950s;
• For the fourth year in a row, Southland residents did not experience a Stage 1 episode, when ozone levels reach 0.20 parts per million and everyone is urged to avoid prolonged outdoor activity. A Health Advisory is declared when ozone levels reach 0.15 parts per million;
• Several areas, including central and northern Orange County, downtown Los Angeles, coastal areas from Long Beach to Malibu and the eastern Coachella Valley did not exceed the federal ozone standard at all this year; and
• Several areas, including the San Bernardino Valley, parts of the San Bernardino Mountains, Mira Loma, Perris and Lake Elsinore areas, the east San Gabriel Valley and the east San Fernando Valley had fewer days exceeding the federal ozone standard this year than last.

The Santa Clarita area experienced the most notable increase this year in unhealthy ozone levels, possibly due to nearby wildfires and a weather pattern that brought an unusually high number of sunny, smog-forming days to the area, Cassmassi said. The Santa Clarita monitoring station also was moved last year to a new location considered more representative of that area’s air quality. The move may be one reason why Santa Clarita experienced a large increase in the number of unhealthy ozone days this year, Cassmassi said.

Smog season officially starts on May 1 and ends Oct. 31. With days growing shorter and temperatures cooler, additional days exceeding the federal ozone level are unlikely this year.

Ozone, a colorless and pungent gas, damages lung cells and may be linked to permanent lung damage. It 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.

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

-#-

AQMD Home Page
This page updated: March 01, 2004
URL: http://www.aqmd.gov/news1/smog_season2002a.htm