July 11, 2003
Following a two-week
period of unhealthy air quality, the Southland had its first Stage 1 smog
episode today since 1998.
A Stage 1 episode was
recorded after 4 p.m. in the central San Bernardino Mountains when ozone levels
reached 0.21 parts per million, considered a very unhealthy level. Several
other areas, including the Santa Clarita, San Fernando, San Gabriel and San
Bernardino valleys, experienced unhealthy levels of ozone.
“Our geography, the
presence of a very strong atmospheric inversion layer, and air pollution from
all sources, from cars to trucks to consumer products, have elevated our smog to
Stage 1 levels,” said Barry Wallerstein, executive officer of the South Coast
Air Quality Management District.
“The first Stage 1
episode in five years underscores the need to aggressively pursue additional
pollution control measures, especially for air pollution sources under federal
and state jurisdiction,” Wallerstein said.
Sources under federal and
state jurisdiction include vehicles of all types, from cars to trucks, trains
and ships. Collectively they are responsible for about 75 percent of
ozone-forming emissions. AQMD’s draft 2003 Air Quality Management Plan calls on
state and federal air quality agencies to speed up efforts to reduce emissions
from these sources, which AQMD for the most part does not have the authority to
regulate.
The 2003 Air Quality
Management Plan, a blueprint for achieving clean air in the region by 2010, is
scheduled for a final public hearing before AQMD’s Governing Board on Aug. 1.
Southland residents have
experienced unhealthy air quality since June 26 due to an unusually strong high
pressure system and resulting inversion layer that traps smog close to the
ground. Air quality is considered unhealthy when ozone levels exceed the federal
health standard of 0.12 parts per million of ozone, averaged over one hour.
A Stage 1 episode is
declared when ozone levels reach a level of 0.20 during a one-hour average. At
that level, most people will notice some adverse effects such as shortness of
breath, and everyone is urged to avoid strenuous outdoor exercise. Those who
are sensitive to smog, including children, the elderly and people with heart and
lung diseases, are advised to stay indoors.
AQMD recorded 12 Stage 1
episodes in 1998, mostly in the central San Bernardino Mountains. That area as
well as far inland valleys typically experience the highest ozone readings in
the region because they are furthest downwind from the western portion of the
Los Angeles Basin, where most air pollution originates. The fact that ozone
takes time to “cook” in sunlight means that the highest concentrations occur
several hours – and many miles – downwind of major sources.
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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