Emissions Durability Period and Air
Index Information On Your Engine
Emissions Label
Engines that are certified to meet the California Air Resources
Board (CARB) Tier 2 Emission Standards must display
information regarding the Emissions Durability Period and Air
Index.The engine manufacturer makes this information available
to the consumer on emission labels.
The Emissions Durability Period describes the number of
hours of actual running time for which the engine is certified to
be emissions compliant, assuming proper maintenance in
accordance with the Operating & Maintenance Instructions.The
following categories are used:
Moderate: Engine is certified to be emission compliant for
125 hours of actual engine running time.
Intermediate: Engine is certified to be emission compliant for
250 hours of actual engine running time.
Extended: Engine is certified to be emission compliant for
500 hours of actual engine running time.
For example, a typical walk-behind lawn mower is used 20 to
25 hours per year.Therefore, the Emissions Durability
Period of an engine with an intermediate rating would
equate to 10 to 12 years.
The Air Index is a calculated number describing the relative
level of emissions for a specific engine family.The lower the Air
Index, the cleaner the engine.This information is displayed in
graphical form on the emisions label.
Emissions Compliance Period On
Engine Emissions Compliance Label
After July 1, 2000 certain Briggs & Stratton engines will be
certified to meet the United States Environmental Protection
Agency (USEPA) Phase 2 emission standards. For phase 2 certified
engines, the Emissions Compliance Period referred to on the
Emissions Compliance label indicates the number of operating
hours for which the engine has been shown to meet Federal
emission requirements. For engines less than 225 cc displacement,
Category C = 125 hours, B = 250 hours and A = 500 hours. For
engines of 225 cc or more, Category C = 250 hours, B = 500
hours and A = 1000 hours.
This engine has an intermediate rating with and Air Index of 3.
The EPA Emissions compliance period is Category C.The
diplacement of these engines is 305 cc.
Below is a generic representation of the emission label typically
found on a certified engine.