United States                Air and Radiation           EPA420-F-03-023
Environmental Protection                               June 2003

Office of Transportation and Air Quality

       is the
The draft nonroad model calculates past, present, and future emission
inventories (i.e., tons of pollutant) for all nonroad equipment categories
except commercial marine, locomotives, and aircraft. Fuel types included
in the model are:  gasoline, diesel, compressed natural gas, and liquefied
petroleum. The model estimates exhaust and evaporative hydrocarbons
(HC), carbon monoxide (CO), oxides of nitrogen (NOx), particulate
matter (PM), sulfur oxides (SOx), carbon dioxide (CO2).  The user may
select a specific geographic area (i.e., national, state, or county) and time
period (i.e., annual, monthly, seasonal, or daily) for analysis.
What are the                          the
          of                             to         and the
The emission inventories produced by the two versions are the same if
the scenario inputs are the same, but NONROAD2002a has a few en-
  " National Inventory Format (NIF) 2.0 output option for the National
    Emissions Inventory (NEI) from the Reporting Utility
  " Update of Florida Bade County (Federal Information Processing
    Standards (FIPS) Code 26025) to Miami-Bade County (FIPS
  9 More "what-if" analysis ability for fuel sulfur-to-sulfate conversion
    rate (this is not expected to be used by state and local air agencies)
                                                 i Printed on Recycled Paper

How      is the                 for
The review period for draft NONROAD2002a will last until August 20,
2003, which is the same as the review period for the proposed Nonroad
Diesel Rule.
       will the final NONROAD        be
A final NONROAD model will be released in 2004, after the final Non-
road Diesel Engine Rule has been published.

What are the major               in
and the            June            version?
Some of the most important changes affect compression-ignition (CI)
engines where the associated NOx and PM inventories are reduced by
about 35 to 50 percent, depending on year and pollutant. The new SOx
inventories are also less than the prior version  about 75 percent less for
compression-ignition (CI) engines and 65 percent less for spark-ignition
(SI) engines. More details of the inventory changes can be found in the
workshop presentations from November 5, 2002, which are available on
the nonroad modeling web page at: www.epa.gov/otaq/nonrdmdl.htm.
      the                                          all of
       final                                          to
No. The model does not fully reflect the new recreational equipment and
large SI engine standards that were published in the Federal Register in
September 2002 (67 FR 68243). These will be added at a later date.
How do I          for                     from the
                           and              ignition
Until these benefits are incorporated into the NONROAD model, users
will need to estimate the exhaust, diurnal, hot soak, running loss, and
permeation emissions and benefits based on the information in the Sep-
tember 2002 Regulatory Support Document for this rule (EPA-420-R-
022). This document can be downloaded from the EPA Office of Trans-
portation and Air Quality web site at: www.epa.gov/otaq/recveh.htm.

            Tier 4                           and fuel
No. These standards will be incorporated into the final version of NON-
ROAD when the rule becomes final.
What is                    on the      of the
                             for official
EPA is allowing the use of the draft NONROAD2002a Model and associ-
ated default inputs in development of inventories supporting State Imple-
mentation Plans (SIPs). Although NONROAD2002a or its default inputs
may change between the public release of the draft and the final version,
now anticipated for 2004, the draft NONROAD2002a Model currently
represents EPA's best tool for estimating nonroad emissions, as evidenced
by the Agency's use in the Nonroad Diesel Engine Notice of Proposed
Rulemaking (NPRM). Therefore we are allowing state agencies to use
the draft model in SIPs during the period between public release of the
draft and final versions of the model.

EPA will not require that inventories developed using the draft version be
updated following release of the final version. However, since this
release does not include the benefits of the September 2002 final rule for
recreational vehicle, large SI, and diesel recreational marine engines, and
it also doesn't include the benefits that will be associated with the final
nonroad diesel rule, states may  choose to update SIPs after EPA releases
the final version of NONROAD.

After the release of the final version of NONROAD, states that are just
beginning new SIP development, or are in the early stages of SIP devel-
opment, should use the final version of NONROAD for those new SIPs.
     the                     for                       of the
        be       for
No. Option files created with previous versions of the model are not
compatible with NONROAD2002a.

How can I                       if I

Please send an email with your question to nonroad@epa.gov or write

    U.S. Environmental Protection Agency
    Assessment and Standards Division
    Air Quality and Modeling Center
    2000 Traverwood Drive
    Ann Arbor, MI 48105