United States                Air and Radiation           EPA420-F-99-004
 Environmental Protection                               January 1999

 Office of Mobile Sources

 The U.S. Environmental Protection Agency (EPA) is proposing a finding
 that spark-ignition (SI) engines rated above 19 kilowatts (25 horsepower)
 contribute to air pollution in ozone or carbon monoxide nonattainment
 areas. EPA intends to propose a national program to control emissions
 from this currently unregulated source to help reduce the harmful health
       of ozone and carbon monoxide.
EPA intends to propose a national program to control emissions of oxides
of nitrogen (NOx), hydrocarbons, and carbon monoxide from large
nonroad SI engines. These engines are used in a variety of industrial
equipment, including forklifts, airport ground-service equipment, genera-
tors, and compressors.  Emissions from large nonroad SI engines account
for approximately 2 percent of total mobile source NOx emissions na-

The results of an EPA study completed in 1990 demonstrated the need for
control of air pollution in the nonroad engine and vehicle arena. EPA
published this finding in conjunction with the first rulemaking to set
emission standards for nonroad engines, which was completed in June
1994. In September 1997, the Agency issued a proposal for more strin-
                                                 > Printed on Recycled Paper

gent emission standards for diesel
engines used in most nonroad applica-
tions. EPA has subsequently finalized
emission standards for nonroad SI
engines rated at or below 19 kilowatts,
which consist predominantly of residen-
tial and commercial lawn care equip-
Many of the engines that would be
affected by these new emission stan-
dards have counterpart engine models
used in highway applications. While
highway engines have seen extensive
technological developments,  the
nonroad engine designs have changed
little to reflect these improvements.
Shifting toward these technologies that have been developed for cars and
trucks, such as electronically controlled closed-loop injection systems
with three-way catalytic converters, there is a great potential to dramati-
cally improve engine performance and fuel economy in addition to the
anticipated emission reductions.
If the standards are implemented as discussed, the resulting emission
reductions would translate into significant, long-term improvements in
air quality in many areas of the U.S. Application of basic automotive
emission control technologies would reduce NOx and hydrocarbon
emissions by 70 to 90 percent. The emission standards being considered
are part of an overall program designed to ensure that engine emissions
are controlled throughout a lifetime of field operation,  not just in the
laboratory. Overall, the program would provide much-needed assistance
to states facing ozone and carbon monoxide air quality problems that are
causing a range of adverse health effects for their citizens, especially in
terms of respiratory impairment and related illnesses.

Protection Agency
EPA desires full public participation in the rulemaking process. The
Agency solicits comments from all interested parties. Wherever appli-
cable, full supporting data and detailed analysis should also be submitted
to allow EPA to make maximum use of the comments. Commenters are
especially encouraged to provide specific suggestions for changes to any
aspects of the proposal that they believe need to be modified or im-

EPA will  accept comments on the proposed finding for 30 days after
publication in the Federal Register. For instructions on submitting
written comments, please see the Federal Register notice, which is
available  from the EPA Air and Radiation Docket by calling 202-260-
7548; please refer to Docket No. A-98-1. In addition, the proposed
finding and related documents are available electronically via the EPA
Internet server at:

       http ://www. epa.gov/om s/nonroad .htm

There will also be an opportunity for oral and written comment when
EPA publishes a subsequent Notice of Proposed Rulemaking.
          Document information is also available electronically at the Internet site
          given above, or by writing to:

                 U.S. Environmental Protection Agency
                 Office of Mobile Sources
                 2000 Traverwood Drive
                 Ann Arbor, MI 48105