| May 15, 2008 As Smog
Season Begins
Starting today, Southland air pollution officials will begin forecasting
and reporting daily ozone air quality using a more stringent federal air
quality standard that could lead to an increase in the number of unhealthful
days forecast.
“Although our air quality is improving, the new standard is more health
protective and could lead to more unhealthy days recorded in the Southland,”
said William Burke, Ed.D., Chairman of the South Coast Air Quality
Management District. “This just underscores the importance of moving
forward with aggressive measures to clean up Southland air and protect
public health.”
The new 8-hour ozone air quality standard, adopted by the U.S.
Environmental Protection Agency (EPA) on March 12, is slightly more
stringent than the old standard adopted in 1997. The new standard is 0.075
parts per million (ppm), slightly lower than the old standard of 0.084 ppm.
During smog season, which began on May 1 and ends on Oct. 31, there will
likely be more days when air quality exceeds the new standard. For example,
the region exceeded the old 8-hour ozone standard on 79 days in 2007
compared to 109 days in 2007 using the new standard.
As part of the new standard, EPA also lowered the ozone concentrations
that correspond to color-coded air quality conditions in the national Air
Quality Index (AQI). This could cause an increase in the number of days
when air quality is forecast to reach the “unhealthy for sensitive people”
and “unhealthy” ranges. (See following table)
An AQI value of 100 corresponds to the national air quality standard set
for a particular pollutant, in this case ozone. An AQI value below 100 is
generally considered to have minimal adverse health impacts for all but the
most sensitive populations.
| Category |
Color |
AQI Value |
8-hour
Ozone Standard adopted in 1997
(0.084 ppm) |
8-hour
Ozone Standard revised in 2008
(0.075 ppm) |
| Good |
Green |
0-50 |
0.000-0.064 |
0.000-0.059 |
| Moderate |
Yellow |
51-100 |
0.065-0.084 |
0.060-0.075 |
| Unhealthy for Sensitive
Groups |
Orange |
101-150 |
0.085-0.104 |
0.076-0.095 |
| Unhealthy |
Red |
151-200 |
0.105-0.124 |
0.096-0.115 |
| Very Unhealthy |
Purple |
201-300 |
0.125-0.374 |
0.116-0.374 |
| Hazardous |
Maroon |
301-500 |
0.375 and above |
No Change |
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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