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Fact #502: January 21, 2008
Off-Road Diesel Equipment Facing Tougher Emissions Regulation

The Environmental Protection Agency began regulating off-road diesel emissions in 2000 with the phase in of Tiers 1-3, which only applied to diesel engines above 50 horsepower. Beginning in January 2008, Tier 4 regulations will include all diesel engines and will in some cases reduce nitrogen oxide and particulate matter limits to levels similar to current on-road diesel engines. Tier 4 regulations will be phased in over a seven year period beginning with the smallest engines and gradually including larger off-road diesel equipment.

Tier 4 Off-Highway Diesel Emission Standards
(grams per horsepower-hour)

Engine Horsepower	Effective Year	PM	NOx
Less than 25	2008	0.3	-
25 to 74	2013	0.02	3.5
75 to 174	2012-2013	0.01	0.3
175 to 749	2011-2013	0.01	0.3
Over 750	2011-2014	0.075	2.6/0.50*
Over 750	2015	0.02/0.03**	0.5***
Notes: PM: Particulate Matter NOx: Nitrogen Oxides hp: horsepower * The 0.50/g/hp-hr applies to generator sets more than 1200 hp. ** The 0.02/g/hp-hr applies to generator sets; the 0.03 g/hp-hr applies to other engines. *** Applies to all generator sets only. - Not regulated Source: U.S. Environmental Protection Agency.

 

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