United States Air and Radiation EPA420-F-02-033
Environmental Protection September 2002
Agency
Office of Transportation and Air Quality
4>EPA Frequently
Asked Questions
Environmental Impacts of Newly
Regulated Nonroad Engines
The U. S. Environmental Protection Agency (EPA) has adopted
emission standards for recreational vehicles, recreational marine diesel
engines, and industrial spark-ignition engines. This information sheet
addresses questions about the environmental impacts of these engines
and how this regulation will improve air quality.
What engines and vehicles are covered by the new
standards?
We are adopting new emission standards for the following three groups
of previously unregulated nonroad engines and vehicles:
• Large industrial spark-ignition engines: Nonroad engines powered
by gasoline, liquid propane gas, or compressed natural gas rated
over 19 kilowatts (kW) (or 25 horsepower). These engines are used
in commercial and industrial applications, including forklifts,
electric generators, airport baggage transport vehicles, and a variety
of farm and construction applications.
• Recreational vehicles: off-highway motorcycles, all-terrain vehicles
(ATVs), and snowmobiles.
• Recreational marine diesel engines: Diesel engines rated at or
above 50 horsepower (37 kilowatt) used in recreational boats, such
as yachts and cruisers.
> Printed on Recycled Paper
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How do engines and vehicles air quality?
Nationwide, these engines and vehicles are a significant source of air
pollution. In 2000, they accounted for about 9 percent of national hydro-
carbon (HC) emissions, 4 percent of carbon monoxide (CO) emissions, 3
percent of oxides of nitrogen (NOx) emissions, and 2 percent of particu-
late matter (PM) emissions from mobile sources. If left uncontrolled, by
2020 these engines will contribute 24 percent of national HC emissions,
6 percent of CO emissions, 9 percent of NOx emissions, and 5 percent of
PM emissions from mobile sources. These estimates for 2020 show
higher relative emission levels, both because of expected growth and
because emission controls for cars, trucks, and other emission sources
will substantially decrease total emissions.
On an individual basis, these vehicles can have very high emission rates.
This is illustrated in the figure below, which compares the emissions
from unregulated recreational vehicles with the emissions from an
automobile meeting our current National Low Emission Vehicle (NLEV)
emission standards. As shown in the figure below, an unregulated two-
stroke off-highway motorcycle (OHMC) can emit as much pollution in
one hour as over 20 automobiles operating for one hour. Similarly, an
unregulated two-stroke snowmobile can emit as much as nearly 100
automobiles.
Comparison of HC+CO+NOx
From Recreational Automobiles
4-stroheOHMC
2-strokeOHMC
4-;4! .>te AT V
'-•:4i.>f(f: ATV
4-gtrete SrwwreSjiSe E^ilfliiiMili^iiiiiii
3«
Cl Marine B||||ii
0 25 50 75 100
The lumber of automobiles* it would take to emit as much pollution
as one of these vehicles emits in the same amount of time
1" - Based o$i net* au toiiab Hes meeting EFA's M_E¥ standards)
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Ozone
Carbon
Monoxide
What are the human health and welfare of
pollutants?
The engines covered by the new standards generally contribute to ozone
formation and ambient PM and CO levels. These pollutants are subject
to our National Ambient Air Quality Standards (NAAQS); states that
exceed NAAQS levels are required to take measures to reduce emis-
sions. In addition, these engines emit Mobile Source Air Toxics.
Ground-level ozone, the main ingredient in smog, is formed by complex
chemical reactions of volatile organic compounds (primarily HC) and
NOx in the presence of heat and sunlight. Ozone forms readily in the
lower atmosphere, usually during hot summer weather. Volatile organic
compounds come from some natural sources (such as vegetation), but
mostly come from motor vehicles, chemical plants, refineries, factories,
consumer and commercial products, and other industrial sources. NOx
emissions come largely from motor vehicles, nonroad equipment, power
plants, and other sources of combustion.
Elevated ozone concentrations remain a serious public health concern
throughout the United States. In 2001, approximately 116 million people
lived in 56 areas designated nonattainment under the 1-hour ozone
NAAQS. Increased ozone concentrations in the air have been associated
with increased hospitalizations for respiratory causes for individuals
with asthma, worsening of symptoms, decrements in lung function, and
increased medication use; chronic exposure may cause permanent lung
damage. Children and people with compromised respiratory systems are
particularly at risk.
CO is a colorless, odorless gas produced from the incomplete combus-
tion of carbon-based fuels. CO enters the bloodstream through the lungs
and reduces the delivery of oxygen to the body's organs and tissues. The
health threat from CO is most serious for those who suffer from cardio-
vascular disease, particularly those with angina or peripheral vascular
disease. Healthy individuals also are affected, but only at higher CO
levels. Exposure to elevated CO levels is associated with impairment of
visual perception, work capacity, manual dexterity, learning ability and
performance of complex tasks.
In 2001, approximately 22 million people lived in 13 areas designated
nonattainment under the CO NAAQS. High concentrations of CO
generally occur in areas with elevated mobile-source emissions. Peak
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concentrations typically occur during the colder months of the year when
mobile-source CO emissions are greater and nighttime inversion condi-
tions are more frequent.
Particulate Particulate matter represents a broad class of chemically and physically
Matter diverse substances. "Fine particulate matter" includes liquid and solid
particles with a diameter of 2.5 microns or less (also known as PM25).
Particulate matter, like ozone, has been linked to a range of serious
respiratory health problems, including premature mortality, aggravation
of respiratory and cardiovascular disease, aggravated asthma, acute
respiratory symptoms, chronic bronchitis, and decreased lung function.
According to our modeling, there were 65 million people living in areas
with annual average PM25 concentrations at or above the PM25 NAAQS.
PM emissions from various sources contribute directly to ambient PM
levels. In addition, emissions of organic carbon, NOx and oxides of
sulfur (SOx) indirectly contribute to ambient PM levels through atmo-
spheric activity. Organic carbon accounts for 27 to 36 percent of fine-
particle mass, depending on the area of the country. The vast majority
(>90 percent) of direct PM emissions from mobile sources are in the
fine-PM size range.
Air Toxics Emissions from the engines covered by this final rule also contain
several Mobile Source Air Toxics, including benzene, toluene, 1,3-
butadiene, formaldehyde, acetaldehyde, and acrolein, which cause a
variety of health-related problems. Users of these engines and vehicles
may experience high levels of personal exposure to these substances. For
example, snowmobile riders and those directly exposed to snowmobile
exhaust emissions can be exposed to benzene levels two to three orders
of magnitude greater than the 1996 national average benzene concentra-
tions. These elevated levels are also known as air toxic "hot spots,"
which are of particular concern to EPA.
Visibility Fine PM is the major cause of reduced visibility in parts of the United
States, including many of our national parks. In particular, HC emissions
from snowmobiles in the winter months can contribute significantly to
the organic carbon fraction of fine particles, which are largely respon-
sible for visibility impairment. In Yellowstone National Park, a park with
high snowmobile usage during the winter months, HC emissions from
snowmobiles can exceed 500 tons per year, as much as several large
stationary sources, and account for nearly 65 percent of annual HC
emissions in the park.
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How would the emissions and air
quality?
When the emission standards for recreational vehicles, recreational
marine diesel engines, and industrial spark-ignition engines are fully
implemented, we expect an overall 71-percent reduction in HC emissions
from these engines, an 80-percent reduction in NOx emissions, and a 57-
percent reduction in CO emissions in 2020. These controls will help
reduce ambient concentrations of ozone, CO, and fine PM. In addition,
they will reduce personal exposure for people who operate, work with or
are otherwise close to these engines and vehicles. They will also improve
visibility in national parks.
What are the health of the new standards?
The human health benefits of this rulemaking include avoiding approxi-
mately 1,000 premature deaths, preventing 1,000 hospital admissions,
reducing 23,400 cases of asthma attacks, and reducing 200,000 days of
lost work. In monetary terms, we estimate these health benefits to be
roughly $8 billion in 2030. There are additional health and welfare
benefits we are unable to quantify.
Where Can I Get IViore Information?
For more information on the environmental and health impacts of these
new emission standards, see the Final Regulatory Support Document for
this final rule (especially Chapter 1—Health and Welfare Concerns). You
can access that document and others related to the rulemaking on our
Web site at:
www.epa.gov/otaq/regs/nonroad/2002/cleanrec-final.htm
You can also contact us at:
U.S. Environmental Protection Agency
Office of Transportation and Air Quality
Assessment and Standards Division
2000 Traverwood Drive
Ann Arbor, MI 48105
Voice-mail: (734) 214-4636
E-mail: asdinfo@epa.gov
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