United States Air and Radiation EPA420-F-98-021
Environmental Protection April 1998
Agency
Office of Mobile Sources
v/EPA Announcement/
Update
Tier 2 Study
In the Tier 2 Study, the Environmental Protection Agency examines
whether it is appropriate to require more stringent emission standards
for new passenger cars and light duty trucks, which make up the
majority of motor vehicles on the road. This study is the first step in
determining if more stringent vehicle standards are needed to meet the
National Ambient Air Quality Standards. In this examination, EPA
assesses the air quality need, technical feasibility and cost
effectiveness of more stringent standards. EPA is not making
determinations now. The study includes a presentation and discussion
of evidence that will support a determination by the Agency on future
regulatory actions.
Background
The Clean Air Act Amendments of 1990 set specific exhaust emission
standards, beginning with the 1994 model year, for light duty vehicles
(LDVs), or passenger cars, and light duty trucks (LDTs), which include
sport utility vehicles, minivans and pick-up trucks. These are "Tier 1
standards." The Act requires EPA to study whether further reductions in
emissions from these vehicles should be required—"Tier 2 standards"—
which could not take effect before the 2004 model year.
Summary of the Tier 2 Study
EPA must address the need for further reductions in motor vehicle emis-
sions to attain and maintain the National Ambient Air Quality Standards,
including, at a minimum, three factors:
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Air quality need for more stringent standards: The study includes
evidence that supports the need for emission reductions beyond those
provided by the Tier 1 standards. Motor vehicle emissions will remain a
significant contributor to air pollution in many areas of the country.
This assessment includes the finding that, in the time frame contem-
plated for potential Tier 2 standards, there will be an air quality need for
emission reductions to aid in meeting and maintaining the NAAQS for
both ozone and particulate matter.
Availability of technology to implement more stringent standards:
The study includes an examination of the technological feasibility of
controlling light duty vehicle and light duty truck emissions beyond the
level of control provided for by Tier 1 emission standards. Evidence is
presented that more stringent LDV and LDT emission standards are
technologically feasible.
Cost effectiveness of more stringent motor vehicle standards: The
technology projected to be available for the 2004 model year and beyond
appears to be comparable or more cost effective than many alternative
means of emissions reductions.
Issues Related to Potential Tier 2 Standards
There are several issues that EPA will take into account when consider-
ing more stringent emission standards for cars and light duty trucks:
Appropriateness of different standards for cars and light duty
trucks: Sport utility vehicles and light pick-up trucks are an increas-
ingly larger portion of passenger vehicles and a growing portion of
emissions from vehicles. EPA will consider whether these heavier
vehicles, which are often used for personal transportation, should have
the same emission standards as passenger cars.
Sulfur in Gasoline: Sulfur in gasoline inhibits the performance of the
catalyst on advanced technology vehicles and has other negative affects
that increase emissions of HC, CO and NOx. EPA is issuing a separate
staff paper that discusses latest information on sulfur impacts on vehicle
emission controls and summarizes various approaches to controlling
sulfur levels in gasoline. A workshop to discuss these issues will be held
on May 12.
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Uniform Fuel Standards: EPA will consider the application of the same
emission standards to vehicles regardless of what fuel is utilized.
Future Standards: Both the National Low Emission Vehicle Program
(NLEV) and California's proposed second phase of LEV standards set a
benchmark for future vehicle emission controls. EPA will examine these
standards to understand their relationship to potential Federal Tier 2
standards.
Completion of the Tier 2 Report to Congress and Tier
2 Standards
The draft Tier 2 Study is being released now to allow for a 45-day public
comment period. Tier 2 Report to Congress will be issued by July 31,
1998, under a draft agreement with the Sierra Club.
Following submission of this Report to Congress, EPA will, through the
rulemaking process, determine whether: 1) there is an air quality need for
further emission reductions; 2) the technology for meeting more stringent
emissions standards will be available; 3) obtaining further reductions in
emissions from light duty vehicles and light duty trucks will be needed
and cost effective. If these conditions exist, EPA plans to promulgate a
final rule by December 1999.
For More Information
A copy of the draft Tier 2 Study and related information are available
electronically from the EPA Internet server at:
http://www.epa.gov/OMSWWW/tr2home.htm
For further information on the draft Tier 2 Study, please contact Karl
Simon at:
U.S. Environmental Protection Agency
Office of Mobile Sources (6401)
401 M Street SW
Washington, DC 20460
202-260-3623
simon.karl@epamail.epa.gov
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