United States Air and Radiation EPA420-F-03-017
Environmental Protection June 2003
Agency
Office of Transportation and Air Quality
and on a
in
77?e pollution emitted by diesel engines contributes greatly to our
nation's air quality problems. Even with more stringent heavy-duty
highway engine standards set to take effect in 2004 and 2007, existing
trucks and buses will continue to emit large amounts of nitrogen
oxides (NOx) and particulate matter (PM), both of which contribute to
serious public health problems in the United States. Fortunately, there
are several techniques and technologies designed to reduce diesel
pollution from existing trucks and buses. Using pollution control
devices such as a diesel particulate matter filter (DPF) is one way
existing engines can be upgraded (or "retrofitted") to pollute less. This
fact sheet discusses diesel particulate matter filters.
What are the health and environmental of
exhaust?
Heavy-duty trucks and buses account for about one-third of NOx emis-
sions and one-quarter of PM emissions from mobile sources. In some
urban areas, the contribution is even greater. The fine particles in diesel
exhaust (known as particulate matter) can penetrate deep into the lungs
and pose serious health risks including aggravated asthma, lung damage,
and other serious health problems. In addition, diesel exhaust is a likely
human carcinogen. Children are more susceptible to air pollution than
healthy adults because their respiratory systems are still developing and
they have a faster breathing rate.
> Printed on Recycled Paper
-------
Diesel exhaust also has environmental impacts. PM from diesel engines
contribute to haze, which restricts visibility. In addition, diesel exhaust
contributes to ozone formation (a component of smog), acid rain, and
global climate change.
What is a Particuiate Filter?
A diesel particulate matter filter (DPF) is a ceramic device that collects
the particulate matter in the exhaust stream The high temperature of the
exhaust heats the ceramic structure and allows the particles inside to
break down (or oxidize) into less harmful components.
What are the of a DPF retrofit?
DPFs reduce emissions of particulate matter by 60 to 90 percent. DPFs
also reduce emissions of hydrocarbons and carbon monoxide by 60 to 90
percent.
the EPA verify emission reductions?
Yes, EPA verifies individual DPFs based on information supplied to the
EPA by the DPF manufacturer. Since EPA generally receives results of
testing conducted on a limited number of diesel engine models, a conser-
vative approach is taken to establish the verified levels of reduction. In
most cases the actual reductions are higher than the verified values. For a
list of DPFs and other technologies that EPA has verified, visit:
www.epa.gov/otaq/retrofit/retroverifiedlist.htm. For more information
about EPAs verification process, visit: www.epa.gov/otaq/retrofit/
retrofittech.htm.
How much a DPF cost?
DPFs for school buses currently cost between $5,000 and $10,000. The
cost depends on the specific bus engine and operating characteristics,
such as exhaust temperatures. Field experience suggest DPFs take about
6-8 hours to install.
What type of fuel a DPF require?
DPFs must be used with ultra-low sulfur diesel fuel (ULSD - 15 parts per
million sulfur). Use of regular diesel fuel in a DPF equipped bus could
eventually clog the filter. This could lead to exhaust back-pressure in-
creases and engine damage.
-------
Currently, ULSD costs between 8 and 25 cents per gallon more than
regular diesel. ULSD is available in many parts of the country now and
will be available nationwide beginning in 2006.
Can a DPF be on any engine?
No. DPFs work best on engines built after 1995. Therefore, knowing the
age and type of each engine in the fleet as well as the exhaust tempera-
ture is an important part of any retrofit project. These factors determine
whether or not vehicles are candidates for filters.
Are there maintenance requirements fora
DPF?
Manufactures of DPFs recommend that the device be cleaned about
every 100,000 miles. Some of the PM collected does not completely
oxidize and inert ash remains in the filter. After about 100,000 miles this
ash should be removed by blowing or vacuuming it out. Generally this
process takes no more than 3 hours.
How long a DPF last?
Most DPFs come with 100,000 to 150,000 mile warranty, and can last 7
to 15 years.
Where can I get a DPF?
For more information about manufacturers of DPFs or other retrofit
equipment visit our Web site at: www.epa.gov/otaq/retrofit/
cont retromfrs.htm.
Where can I find more information?
For more information on these topics, please visit these EPA Web sites:
* Voluntary Diesel Retrofit Program: www.epa.gov/otaq/retrofit
* Clean School Bus USA - Basic Information on Retrofit Options:
www.epa.gov/otaq/schoolbus/retrofit.htm
-------
• Clean Diesel Independent Review Panel: www.epa.gov/air/caaac/
clean_diesel.html
* Health Assessment Document for Diesel Engine Exhaust: http://
cfpub. epa.gov/ncea/cfm/recordisplay. cfm?deid=29060
You can also contact the Office of Transportation and Air Quality library
for document information at:
U.S. Environmental Protection Agency
OTAQ Library
2000 Traverwood Drive
Ann Arbor, MI 48105
Phone:734-214-4311
Email: GroupAALibrary@epa.gov
------- |