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                                 SEP  2 4 2008

 Dear Manufacturer or other Interested Party:

 Subject: Implementing Nitrogen Dioxide Limits for Retrofit Technologies

 This letter addresses the implementation of nitrogen dioxide (NO2) limits for diesel
 retrofit technologies verified under the US Environmental Protection Agency's (EPA's)
 National Clean Diesel Campaign (NCDC). As described in the December 20, 2007
 notice EPA420-B-08-005 (http://www.epa. gov/otaq/retrofit/documents/420b08005.pdf),
 the NCDC will implement a requirement that limits the increase in NO2 emissions
 associated with some types of retrofit technologies to levels no greater than 20 percent
 above baseline engine levels. This requirement takes effect on January 1, 2009.

 In order to demonstrate that technologies do not exceed this emission limit, all
 manufacturers of EPA-verified retrofit technologies must provide emission test data to
 EPA by November 1 , 2008 or those technologies will be removed from the NCDC
 Verified Technology List as of January 1, 2009.  As EPA is working to harmonize with
 the similar California Air Resources Board (ARE) requirement also effective
 January 1, 2009,  we expect manufacturers should provide the same data and information
 to EPA and ARE regarding the increase in NO2 emissions from these technologies.
 Verified technologies for which EPA does not have NOi data and which utilize catalytic
 reduction to reduce emissions and/or aid in the combustion of particulates will be
 removed from EPA's Verified Technology List on January 1 , 2009.

 As manufacturers and fleets prepare for changes in  available verified technologies, there
 have been some questions about when products may be sold or installed if they face
 removal from the Verified Technology List as of January 1, 2009. Verified products that
 do not meet the NO2 emission limit may remain in service, provided they are installed
 prior to January 1, 2009. However, as of January 1, 2009, technologies that do not meet
 the N02 emission limit may not be installed or sold as EPA verified technologies, except
 as described below.

 EPA recognizes that completion of a contract or grant project to install verified
 technologies may require a significant amount of time and experience unforeseen delays.
 To facilitate the completion of contracts and grants executed in advance of the
January 1, 2009 deadline, EPA is instituting a grace period.  Installation of technologies
that do not meet the NO2 emissions limit may continue through March 31, 2009, provided
the sales contract to the final purchaser was executed no later than December 31, 2008.

EPA recommends fleets and manufacturers prepare for the implementation of this
emission limit. Contracts and competitive bids for retrofit technologies should specify
that devices meet this NOa limit if the sales agreement and installation may not occur
within the dates described above.  Additionally, manufacturers of verified technologies
are responsible for meeting this requirement. As of January 1, 2009, manufacturers may
not represent or sell technologies as verified when responding to bids or contracts unless
the product has been evaluated and verified by EPA or ARB as meeting this emission

If you have questions regarding this new emission limit, please contact Dennis Johnson
of my staff at 202-343-9278 or by e-mail at johnson.dennis@epa.gov.
Jim Blubaugh, Manager
Innovative Strategies Group
Office of Transportation and Air Quality