United States              Air and Radiation           EPA420-F-97-011
Environmental Protection                              March 1997
Agency
Office of Mobile Sources
Environmental
Fact Sheet
Approval of Urban  Bus Retrofit/
Rebuild Equipment
The Environmental Protection Agency (EPA) is approving an
engine retrofit kit for certain urban transit buses that will
significantly reduce particulate matter (PM) compared to
current technology. This is the first retrofit/rebuild equipment
that has demonstrated compliance with the stringent 0.10
grams per brake horsepower-hour (g/bhp-hr) PM standard. It
is expected to reduce PM emissions by as much as 80
percent per bus compared to pre-retrofit levels.
Urban Bus Retrofit/Rebuild Program
On April 23, 1993, EPA finalized the Urban Bus Retrofit/Rebuild
Program which is intended to reduce the ambient levels of PM in
urban areas. The program is limited to 1993 and earlier model year
urban buses operating in metropolitan areas with 1980 populations
of 750,000 or more, whose engines are rebuilt or replaced after
January 1, 1995. Approximately 40 urban areas are affected.
Operators of the affected buses are required to choose between two
compliance options: Program 1 sets PM emissions requirements for
each urban bus engine in an operator's fleet which is rebuilt or
replaced; Program 2 is a fleet averaging program that establishes
specific annual target levels for average PM emissions from urban
buses in an operator's fleet.

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A key aspect of the program is the
certification of retrofit/rebuild
equipment. To meet either of the two
compliance options, operators of the
affected buses must use equipment
which has been certified by EPA.

Under Program 1, a transit operator must
use equipment certified by EPA as
meeting a 0.10 g/bhp-hr PM standard, if
such equipment is available for a life
cycle cost of $7,940 or less (in 1992
dollars). If such equipment is not
certified, then a transit operator must use
equipment certified by EPA as achieving
at least a 25 percent reduction in PM, if
such equipment is available for a life
cycle cost of $2,000 or less. If such
equipment is not  available, a transit
operator must rebuild to the original
engine configuration, or a configuration
having the same or lower emissions.
Equipment used for Program  2 must be
certified as providing some level of PM
reduction that would in turn be claimed
by urban bus operators when  calculating
their average fleet PM levels attained
under the program.
New Retrofit Kit Approved
EPA has certified equipment
manufactured by Engelhard Corporation
as meeting the requirements of the
Urban Bus Retrofit/Rebuild Program.
Engelhard Corporation requested EPA
approval in January, 1996, and after a
public review period and resolution of
comments, EPA has granted the
approval. This certification applies to
urban buses with 1979 through 1989
model year Detroit Diesel Corporation
6V92TA engines with mechanical unit
fuel injectors.

This is the first retrofit kit that has
demonstrated compliance with the
stringent 0.10 g/bhp-hr PM standard. It
will reduce PM emissions by as much as
80 percent per bus compared to pre-
retrofit levels. Previously approved
retrofit kits reduce PM emissions by 25
to 40 percent per bus.

Approval of this new technology does
not affect engines originally certified by
EPA as meeting California emissions
standards. For urban buses other than
those described above, the requirement
to install EPA-approved equipment
reducing PM by 25 percent will remain
in effect until such time as equipment is
certified for  such buses which complies
with the 0.10 g/bhp-hr PM standard.
Health and Environmental
Benefits
This certification will result in reduced
PM emissions in approximately 40 urban
areas covered by the program, thus
helping states improve air quality. PM is
a contributor to air pollution in both
urban and rural areas. PM has been
identified as a probable human
carcinogen. High levels of exposure also
cause increased frequency of bronchitis,
asthma attacks and respiratory
infections. Environmental impacts of
PM include reduced visibility and
deterioration of buildings.

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Affect on Industry
Prior to certification of this new
technology, affected transit operators
were required to install, at the time of
engine rebuild, retrofit kits approved by
EPA as achieving a 25 percent PM
reduction. Such retrofit kits are available
for approximately $2,000 incremental to
the cost of a typical rebuild. However, as
a result of this approval, transit operators
who rebuild 1979 through 1989 model
year Detroit Diesel Corporation
6V92TA engines with mechanical unit
fuel injection will be required to install
an EPA-approved retrofit kit meeting a
stringent 0.10 g/bhp-hr PM standard.
The cost  of such equipment may be up
to $7,940 incremental to the cost of a
typical rebuild.

EPA determined in the original
rulemaking for this program that such
costs resulted in a cost-effective PM
reductions. In an effort to lessen the cost
impact of this decision on transit
operators, EPA has approved several kit
supply options aimed at providing
increased purchasing flexibility.
   TTNBBS: 919-541-5742 (1200-
   14400 bps, no parity, 8 data bits,
   1 stop bit);
   voice helpline: 919-541-5384

Information is also available by calling
202-233-9322 or writing to:

   U.S. EPA
   Office of Mobile Sources
   EPCD/ECPG (6403J)
   401 M Street SW
   Washington, DC 20460
For More Information
Information on the Urban Bus Retrofit/
Rebuild Program is available
electronically via the EPA Internet
server or via dial-up modem on the
Technology Transfer Network (TTN),
an electronic bulletin board  system
(BBS).
   World Wide Web: http://www.epa.
   gov/OMSWWW

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