Sept. 23, 2003
Air Quality
Officials Call for Greater Controls on Mobile Sources
Due in large part to unusually hot and stagnant
summer weather, Southern California has endured its worst ozone smog season
since 1997, air quality officials said today.
“After more than a decade of steadily improving
air quality, the trend has leveled off,” said Barry Wallerstein, executive
officer for the South Coast Air Quality Management District.
“While weather is the major player in this year’s
smog season, reducing emissions from vehicles is the key to improving air
quality in the future.
“The state and federal governments have sole
jurisdiction over emissions from all kinds of vehicles, from cars and trucks to
ships, trains and planes. They must step up their efforts to dramatically cut
emissions from the vehicle sector, which is responsible for about 75 percent of
our smog problem.”
On Oct. 23, the California Air Resources Board
will conduct a public hearing in Diamond Bar on AQMD’s 2003 Air Quality
Management Plan, the blueprint for achieving federal clean-air standards in the
region by 2010. At that hearing, AQMD officials will urge CARB’s Board to
incorporate into the air plan more measures for reducing vehicle pollution.
Southland Still Smoggiest Region in the Country
As of Sept. 22, the region had experienced 63 days
of unhealthy air quality, when ozone levels exceeded the federal one-hour ozone
standard of 0.12 parts per million (ppm). That far exceeds the 49 days of
unhealthy air quality during 2002 and 36 days in 2001.
The number of unhealthy days this year also was
more than twice that of the two other smoggiest areas in the country -- the San
Joaquin Valley and Houston -- which had exceeded the federal health standard on
33 days and 25 days respectively, as of yesterday.
As a final measure of this smog season’s severity,
the Southland had its first Stage 1 ozone episode this summer since 1998.
During a Stage 1 episode, air quality is considered very unhealthful and ozone
levels reach a level of 0.20 during a one-hour average. This year’s Stage 1
episode occurred on July 11 in the central San Bernardino Mountains when ozone
levels reached a peak of 0.216 ppm.
In addition to the single Stage 1 episode, the
region had four days when ozone reached a near-episode level of 0.19 ppm -- on
May 28, July 10, July 13 and July 14.
Ozone smog season officially ends on Oct. 31 and
there could be more unhealthful days to come. However, the potential for smoggy
days diminishes as autumn brings shorter days and lower temperatures.
The Weather Factor
AQMD scientists are evaluating a number of
potential causes for the high number of unhealthful days this year, from the
introduction of ethanol as a substitute for MTBE in gasoline to suburban growth
to the growing number of SUVs on the road. The chief factor, however, was the
weather.
“Due to unusually strong and persistent high
pressure systems, we had very favorable conditions for smog formation this
summer,” said Joe Cassmassi, AQMD’s senior meteorologist.
High-pressure weather systems build strong
atmospheric inversion layers that trap pollutants in the first few thousand feet
of the atmosphere and allow them to build up in concentration from one day to
the next.
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.
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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