MILD SUMMER CONTRIBUTES TO CLEANEST SMOG SEASON ON RECORD

Nov. 4, 2004

Thanks to cooler weather this summer and continued progress in air pollution control programs, the Southland experienced its cleanest smog season in 25 years.

“Unlike last year, when unusually hot weather brought poor air quality, this summer’s moderate temperatures helped make this the cleanest smog season on record,” said Barry Wallerstein, executive officer for the South Coast Air Quality Management District.

“Cleaner cars, businesses and industries also have helped drive a long-term trend of air quality improvement,” he said.

This year, there were 27 days when ozone levels exceeded the federal one-hour standard, compared to 68 days last year.  (See following chart)

Several factors contributed to this year’s milder smog season including “June gloom” conditions that lasted until early July, weak high-pressure systems and record rains in late October, said Joe Cassmassi, AQMD’s senior meteorologist.

This year’s weather and air quality was in sharp contrast to last year, when record-strength high-pressure systems brought high temperatures, strong atmospheric inversions and as a result, the worst smog season in six years.

“Although the weather gave us a major assist this year, we still face a significant challenge in achieving our air quality goals,” Wallerstein said, noting that there were 88 days this year exceeding the federal 8-hour ozone standard.

In addition, the average number of days exceeding the 8-hour standard shows no substantial improvement during the past five years, he said.

“We continue to need the state and federal governments to do their fair share by tackling under-regulated, highly polluting mobile sources including trains, planes, ships and construction equipment,” he said.

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.

Comparison to other Areas

Two other areas with historically severe ozone problems – the San Joaquin Valley and Houston – had worse air quality than Southern California this year by certain measures.  But the Southland had the worst air in the nation as measured by its peak 8-hour ozone level.

2004 Comparison of Ozone Levels for Top Three Smoggiest Areas in US

Numbers in bold indicate peak 2004 level in United States as of Nov. 1

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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