AMQD News, Oct. 12, 1999

First Year With No Stage 1 Episodes

SUMMER SMOG SEASON CLEANEST IN MODERN HISTORY

Southern California has just concluded the cleanest summer smog season on record and its first without a single Stage 1 episode day for ozone since air monitoring began some 50 years ago.

The highest recorded level of ozone this year was .17 parts per million (on June 20 in the Central San Bernardino Mountains), falling short of the .20 ppm level needed for a Stage I Episode, during which AQMD advises all people to avoid vigorous outdoor exercise and sensitive individuals to remain indoors.

Overall, the smog season this summer was the cleanest on record with 43 days above the .12 ppm federal one-hour standard for ozone, compared with 62 days last year, 68 days in 1997 and 90 days in 1996. Ten years ago in 1989 there were 157 days above the standard and twenty years ago in 1979 there were 191 days.

"Our air was cleaner this summer than at any time since smog became a public concern in the 1940s," said Barry Wallerstein, executive officer of the South Coast Air Quality Management District. "At the beginning of the decade, we predicted that Stage I episodes would end by 2000. It appears the region is right on schedule, although we still could see some Stage 1 episodes over the next few years if the region experiences extremely stagnant weather."

Ten years ago in 1989 the area experienced 54 Stage 1 episodes and 20 years ago in 1979 the region had 120 Stage 1 episodes. There were 12 Stage 1 episodes in 1998 and one in 1997.

This year, the region had only 12 state health advisory days for ozone, compared to a total of 43 in 1998 and 28 in 1997. At this lower level of ozone – between .15 ppm and .20 ppm -- AQMD advises everybody to avoid prolonged vigorous outdoor exercise and susceptible people to avoid outdoor activity.

Wallerstein noted that the number of people breathing unhealthful levels of ozone has fallen as the geographic size of the region’s smog cloud has shrunk.

"Remarkably, Orange County did not have a single day over the federal ozone standard this summer and Los Angeles County had just a few days," he said. "Without exception, all areas have become cleaner." (The following table provides historical ozone levels at selected sites in the region.)

Wallerstein said improved air quality this year is part of a long-term trend toward cleaner air due to local and state efforts to reduce air pollution and also due to unusually cool weather this summer.

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