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.
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|
AQMD Preliminary Data:
Days Over Federal 1-hour Ozone Standard of .12 Parts per
Million
|
|
AQMD Air Monitoring Station |
1999* |
1998 |
1997 |
1989 |
|
Central Los Angeles |
1 |
5 |
0 |
34 |
|
East San Fernando Valley |
0 |
7 |
2 |
40 |
|
West San Gabriel Valley |
0 |
14 |
5 |
80 |
|
East San Gabriel Valley |
3 |
28 |
18 |
121 |
|
Central Orange County |
0 |
2 |
0 |
13 |
|
Central San Bernardino |
15 |
39 |
32 |
115 |
|
Riverside Metropolitan Area |
3 |
32 |
13 |
113 |
|
Central San Bernardino Mountains |
36 |
57 |
29 |
127 |
|
North Coachella Valley |
1 |
8 |
4 |
37 |
|
South Coast Air Basin Total** |
43 |
62 |
68 |
157 |
* The ozone standard was not exceeded during 1999 in Orange County and was
exceeded in Los Angeles County only in downtown Los Angeles and the East San
Gabriel and Pomona valleys.
** Does not include Coachella Valley
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