May 23, 2003
In a departure from recent years, Southland smog levels have reached
unhealthy levels for the week prior to Memorial Day due to weather favorable to
ozone formation.
“Although the long-term air quality trend continues to improve, the beginning
of smog season reminds us that Southern Californians still experience many days
each year when air quality exceeds health-based standards,” said Barry
Wallerstein, executive officer of the South Coast Air Quality Management
District.
“For that reason, residents should pay close attention to air pollution
forecasts during smog season and adjust their activities – and those of their
children – as appropriate.”
Since last Friday, the region has had seven days in a row of unhealthy air
quality – a pattern typically not seen until mid- to late-summer. In addition,
the first day of unhealthy air frequently does not occur until mid- to
late-June. Air quality is unhealthy when ozone levels exceed the federal
one-hour standard of 0.12 parts per million, or greater than 100 on the Air
Quality Index.
The peak ozone level this week was 0.143 parts per million on May 21 in
Riverside. The central San Bernardino Mountains -- typically the area with the
highest number of unhealthy days during smog season -- had five days exceeding
the federal ozone standard this week. Inland areas including the San Bernardino
Valley, the east San Gabriel Valley and the Santa Clarita area have had one or
two days of unhealthy ozone levels. Most other areas have not yet experienced
unhealthy ozone this year.
Even though air quality has been unhealthy for several days, it has not been
particularly widespread or prolonged. Unhealthy levels on some of the days
occurred only at one location for one hour.
Today’s forecast calls for air quality that is unhealthy for sensitive
individuals in the inland valleys and mountains. A cooling trend this weekend
should improve air quality throughout the region.
“Although smog season has started with several unhealthy days, it’s difficult
to predict how the rest of the summer will unfold,” said Joe Cassmassi, AQMD’s
senior meteorologist.
“We do know that the long-term trend is toward improving air quality due to
increasingly strict air pollution controls on a wide range of sources, from
paints to automobiles.”
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”
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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