United States Air and Radiation EPA420-F-97-022
Environmental Protection December 1997
Agency
Office of Mobile Sources
v>EPA Environmental
Fact Sheet
Episodic Emission Control Programs
The dramatic increase in the number of miles being driven in recent
years threatens to overwhelm the technological advances made with
respect to vehicle emissions reductions and has contributed to urban
gridlock and highway congestion. The Environmental Protection Agency
(EPA) is committed to providing states and local areas with support in
their efforts to meet air quality standards. The implementation of
episodic emission control programs is becoming increasingly popular
across the country as an innovative approach to reduce emissions of
ozone precursors, carbon monoxide, and particulate matter.
Episodic Emission Control Programs
The dramatic increase in the number of miles being driven in recent
years threatens to overwhelm the technological advances made with
respect to vehicle emissions reductions and has contributed to urban
gridlock and highway congestion. EPA is committed to providing states
and local areas with support in their efforts to meet air quality standards.
The implementation of episodic emission control programs is becoming
increasingly popular across the country as an innovative approach to
reduce emissions of ozone precursors, carbon monoxide, and particulate
matter.
What Are These Programs?
The episodic emission programs being implemented in many U.S. cities
provide steps that the public and industry can take to reduce emissions
when weather conditions that contribute to high ozone (smog) levels are
forecast. The programs are usually voluntary. They emphasize educating
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the public about the impact that individual activities can have on local air
quality and about the basics of air pollution (e.g., "good" stratospheric
ozone vs. "bad" ground-level ozone). The education programs inform the
public of activities that can reduce pollution on both an intermittent
"episodic" basis (e.g., reduction of trips, postponement of certain activi-
ties) and on a longer term basis (maintenance of cars).
Motivation for implementation of this type of program often stems from
local government and business concerns about the attainment status of
the area (a designation indicating the severity of the ozone problem) and
the restrictions that might apply to that status, additional controls to
reduce ozone, and costs associated with reelassification into a different
attainment status. Many areas are also motivated by public health con-
cerns and believe that increasing the amount of air quality information
available to sensitive populations raises awareness and results in signifi-
cant health benefits. Specific goals usually associated with episodic
control programs include:
* Educate the public
• Attain air quality standards (NAAQS)
• Meet specific emission reduction targets
• Manage/reduce congestion
• Maintain economic benefits associated with attainment status
• Protect public health
« Maintain air quality standards
Episodic programs are appealing to areas that have significant emissions
from sources such as onroad vehicles, which are traditionally difficult to
reduce due to driver behavior. The programs may also offer additional
emission reductions, that historically are not easily obtained on an
ongoing basis, during a time when the impacts of emission reductions
are the most critical. Public education efforts may also reduce emissions
over the long term, due to increased public awareness of the air quality
impacts of changed behavior. These public education efforts serve the
general public and help them to understand their role in air quality
planning. The education component of these programs also helps to
create a strong link between environmental goals (attainment) and
associated public health benefits.
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Are the Air
Most episodic control programs are designed to limit the number of
times the ozone (or other pollutant) standard is exceeded, and therefore
should have a positive impact on air quality. When episodic control days
are forecast, notification through various means (e.g., TV, radio, etc.) is
undertaken to raise awareness of the general public and encourage
individuals to make behavioral changes. Emission reductions associated
with changes in individual behavior can be significant if a large number
of individuals limit activities that are associated with production of
emissions, such as driving, use of small engines, and refueling.
Long-term emission reduction measures currently in place are expected
to lower long-term average (annual average) concentrations of pollutants
in urban areas, but may not be enough to completely avoid violations of
short-term standards (one-hour or eight-hour average) during severe
ozone episodes. Because episodic controls have been designed to cut
emissions by larger amounts for shorter periods, they have the potential
of being more effective in reducing short-term air quality violations.
To stay in attainment of air quality standards, areas must reduce and
eventually eliminate the number of air quality violations. Activities that
cannot be eliminated on a long-term basis, such as lawn maintenance or
tank refilling, can be restricted on ozone alert days and result in reduc-
tions of emissions and improvement of air quality.
Are the
In addition to reduced pollutant exposure of the general population due
to improved air quality on days having a high potential for ozone forma-
tion , there are other health benefits directly associated with episodic
control programs. Several population groups are more susceptible to the
harmful health effects of ground-level ozone: the elderly, children, and
asthmatics. Public education or programs directly targeting these groups
may provide the most significant benefits of an episodic control pro-
gram. Early awareness of a potential high ozone day may help these
groups limit their outdoor activities and therefore limit their potential for
over exposure to ozone.
The American Lung Association (ALA) has measured the effects of
ozone on emergency room visits. Its report finds that ground level ozone
is linked with 10,000 to 15,000 hospital admissions for respiratory
conditions (including asthma, pneumonia, influenza, bronchitis, and
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chronic obstructive pulmonary disease) in 13 cities during the 1993 and
1994 high ozone seasons. The report links 30,000 to 50,000 emergency
room visits with high ozone levels, and cites increasing evidence that
these effects occur at levels at or below the current ozone standards.
Many cities, such as Los Angeles and Houston, continue to exceed the
0.12 ppm summertime standard.
The ALA study highlights the specific link between ground-level ozone
concentrations and health effects on susceptible populations. While the
principal investigators note that their methodology does not account for
all factors (e.g., demographics and other factors associated with the use
of emergency rooms), the results do indicate that high concentrations of
ground-level ozone can be statistically associated with emergency room
visits and hospital admissions.
Implementation of effective episodic control programs can mitigate these
effects in three direct ways. First, communication and outreach programs
can inform the public—and specific susceptible populations—about the
potential public health risks due to increases in ground-level ozone.
Second, accurate forecasting and subsequent notification of alert days
can allow people in these susceptible populations to change their behav-
ior to limit their exposure. Third the long-term impact of the episodic
control program may reduce concentrations of ground-level ozone and
further cut the exposure to susceptible populations and all other resi-
dents.
For
For more information on Episodic Emisson Control Programs, please
contact Michael Ball at:
U.S. Environmental Protection Agency
Office of Mobile Sources
2000 Traverwood Drive
Ann Arbor, MI 48105
Phone: (734) 214-4897
Fax: (734) 214-4052
E-mail: ball.michael@epa.gov
Information on episodic control programs is available electronically at
the Survey Of Episodic Control Programs page on EPA's Internet World
Wide Web (WWW) site:
http://www.epa.gov/oms/reports/episodic/study.htm
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