United States              Air and Radiation          EPA420-F-00-014
                    Environmental Protection                           April 2000
                    Agency
                    Office of Transportation and Air Quality
vvEPA       Emission
                   Facts
                    The History of Reducing Tailpipe
                    Emissions from Cars and Light
                    Trucks
                    1970-1975: The First Standards
                    In 1970, Congress passed the Clean Air Act, which called for the first
                    exhaust (tailpipe) emissions standards. The pollutants limited were
                    carbon monoxide (CO), volatile organic compounds (VOC), and oxides
                    of nitrogen (NOx). The new standards took effect for the 1975 model
                    year, with a NOx standard for cars and light-duty trucks of 3.1 grams
                    per mile (gpm).
                    1977-1988: Tightening Standards for the First Time
                    In 1977, Congress amended the Clean Air Act and tightened emission
                    standards in two steps: First, between 1977 and 1979, the NOx standard
                    was lowered to 2.0 gpm for cars. Then in 1981, the NOx standard for
                    cars was reduced to 1.0 gpm. Effective in 1979, pursuant to the Clean
                    Air Act requirements, EPA tightened NOx standards for light-duty
                    trucks to 2.3 gpm. Effective in 1988, EPA then set the first tailpipe NOx
                    standards for heavier light-duty trucks at 1.7 gpm, and revised the
                    standard for lighter trucks to 1.2 gpm.
                    1990-1994: Tier 1 Standards
                    In 1990, Congress again amended the Clean Air Act, further tightening
                    emission standards. The NOx standard was set at 0.6 gpm for cars,
                                                             > Printed on Recycled Paper

-------
effective in 1994. The new standards  known as "Tier 1" represent a
40 percent reduction from the 1981 standard. For light-duty trucks, the
new standard ranged from 0.6 to 1.53 gpm, depending on the weight of
the vehicle.

The Clean Air Act Amendments of 1990 also required EPA to assess the
air quality need, cost effectiveness, and feasibility of tighter emission
standards for the 2004 model year and beyond.
1998: Voluntary Agreement For Cleaner Cars
In 1998 the Clinton Administration, along with the automotive industry
and the Northeastern states, reached an innovative, voluntary agreement
to put cleaner cars on the road before they could be mandated under the
Clean Air Act. The new cars are called National Low Emission Vehicles
(NLEV). The first NLEV cars under the agreement reached consumers in
New England in the 1999 model year, and will be available in the rest of
the country for model year 2001. NLEV cars operate under a NOx
standard of 0.3 gpm, an additional 50 percent reduction from the Tier 1
standards. The NLEV agreement also called for a 0.5 gpm NOx standard
for the lighter light-duty trucks only, a 17 percent reduction from Tier 1
requirements for these vehicles.

In 1998, as required by the Clean Air Act Amendments of 1990, EPA
issued the "Tier 2 Report to Congress." The report contained strong
evidence of the need, cost-effectiveness and feasibility for tighter tailpipe
emission standards in the future (beginning in the 2004 model year).
Three main factors supported EPA's decision:

   1. Highway vehicles currently account for 30 percent of smog-forming
     emissions (VOC and NOx) nationally, and because the total number
     of miles driven is increasing (up 127 percent since 1970), they will
     continue to be a significant contributor to pollution;

  2. Larger, heavier vehicles, such as sport-utility vehicles (SUVs), that
     currently are not required to meet the same tailpipe emission stan-
     dards as cars, pollute three to five times as much as do cars and
     make up 50 percent of the vehicles sold today; and

  3. The technology to meet more stringent emission standards is avail-
     able and cost-effective.

-------
In 1998, EPA also determined that sulfur reductions in gasoline are
needed to enable the full performance of low emission-control devices.
(Sulfur is not an inherent or necessary component of gasoline, but rather
is a contaminant introduced during the refining process; limiting the
allowable levels of sulfur in gasoline will allow new technology catalytic
converters to operate at their intended effectiveness and to continue to
perform well for longer periods of time.)
      Tier 2
In 2000, EPA finalized the Tier 2 tailpipe emissions standards, to take
effect beginning in the 2004 model year. This represents the first time
that both cars and light-duty trucks will be subject to the same national
pollution control requirements. The new standard is 0.07 gpm for nitro-
gen oxides, a 77 percent reduction for cars, and a 86-95 percent reduc-
tion for light trucks, beyond the NLEV agreement. EPA also proposed a
reduction in average sulfur levels to 30 parts per million (ppm), with a
maximum allowable sulfur level of 80 ppm, to  achieve the full perfor-
mance of vehicle emission control technologies.

As part of these new standards, EPA has included several measures to
ensure maximum flexibility and cost-effectiveness. These include:

   *  emissions averaging  within each manufacturer's fleet to  achieve the
     0.07 standard;

     allowing additional time for larger light trucks (those between 6000
     and 8500 pounds gross vehicle weight (GVW)), and smaller petro-
     leum refiners, to meet their respective standards; and

   *  allowing for a market-based credit trading-and-banking system for
     both industries to reward those who lead the way in reducing
     pollution.

-------
         Cars
Model
Year
NOx
Standard
(gpm)
NOx
reduction
(from
previous
standard)
1975


3.1






1977


2



35%


1981


1.2



50%


1994


0.6



40%


1999/2001
(NLEV)

0.3



50%


2004-2007


0.07



77%


SUVs,
    (Up to 6000 Ibs)
Model
Year

NOx
Standard
(gpm)
Reduction
(from
previous
standard)
1975



3.1



1979



2.3


26%
1988



1.2


48%
1994



0.6


50%
19997
2001
(NLEV)

0.5


17%
2004-2007



0.07


86%

-------
        SUVs,
                  6001  and        Ibs)
Model
Year
NOx
Standard

Reduction
(from
previous
standard)
1988

1.7




1994

1.53


10%

2004-2007

0.2


87%

2008-2009

0.07

65%
(95% from
the 1994
standard)
For
You can access additional documents on emission standards for cars and
light trucks electronically from the Office of Transportation and Air
Quality web site at:

    http://www.epa.gov/otaq/ld-hwy.htm

More information on the Tier 2 standards is available on the Tier 2 home
page at:

  http ://www. epa.gov/otaq/t2home.htm

You can also contact the National Vehicle and Fuel Emissions
Laboratory's library for additional information and documents, by mail
or phone, at:

  U.S. Environmental Protection Agency
  Office of Transportation and Air Quality
  NVFEL Library
  2000 Traverwood Drive
  Ann Arbor, MI 48105
  (734)214-431'

-------