EPA's Tier 2 Emission Standards for New Motor Vehicles: A Fact Sheet

Order Code RS20247

Updated June 12, 2000

CRS Report for Congress

Received through the CRS Web

EPA's Tier 2 Emission Standards for

New Motor Vehicles: A Fact Sheet

(name redacted)

Environmental Information Analyst

Resources, Science, and Industry Division

The Clean Air Act Amendments of 1990 established “Tier 1” standards to limit

tailpipe emissions from new motor vehicles. The law also required the Environmental

Protection Agency (EPA) to determine if stricter controls would be necessary by model

year (MY) 2004 to assist states in attaining or maintaining the National Ambient Air

Quality Standards. EPA also was required to assess the availability and cost-effectiveness

of technologies necessary to control emissions. In a report submitted to Congress in

August 1998, EPA concluded that tougher standards are necessary and that essential

technologies are available and cost-effective.1 As a result, EPA finalized stricter “Tier 2”

standards on February 10, 2000.2 The new standards will be phased in beginning in

MY2004 and will require all new passenger cars and light trucks up to 8,500 pounds, and

all new heavier passenger vehicles up to 10,000 pounds (including large sport-utility

vehicles), to demonstrate full compliance by MY2009. To improve the efficiency of

emission control technologies, oil refiners also will be required to limit gasoline sulfur

levels to an average of 30 parts per million (ppm) nationwide beginning in 2005, roughly

90% less than the current national average of 340 ppm.

The new Tier 2 standards will require vehicle manufacturers to reduce tailpipe

emissions of carbon monoxide (CO), formaldehyde (HCHO), nitrogen oxides (NOx), nonmethane organic gases (NMOG), and particulate matter (PM). However, manufacturers

will have the flexibility to average the NOx emissions of their vehicle fleets to demonstrate

compliance with the standards instead of certifying each vehicle according to the same

stringency. The standards will require the most reductions in emissions of NMOG and

NOx to help control the formation of ground-level ozone pollution. Relative to the Tier

1 standards, the fleet average standard for NOx will require vehicle manufacturers to

reduce overall tailpipe emissions by 88% to 95%. The standards also will require at least

an 80% reduction in PM emissions but will require less stringent reductions in CO

emissions. The standard for HCHO is a new requirement that is intended to reduce

emissions of carcinogenic pollutants. The table on page 2 compares the current Tier 1

standards, which became effective in MY1994, to the new Tier 2 standards that will be

phased in beginning in MY2004.

1

EPA. Office of Air and Radiation. Tier 2 Report to Congress. July 31, 1998. 55 p.

2

EPA. Federal Register. February 10, 2000. p. 6698-6870.

Congressional Research Service ˜ The Library of Congress

CRS-2

Comparison of Tier 1 and Tier 2 Tailpipe Emission Standards for Motor Vehicles

Intermediate Useful Life (grams/mile) a

Vehicle Type/Weight

NMHC/

NMOG b

CO

NOx

PM

Full Useful Life (grams/mile) a

HCHO

NMHC/

NMOG b

CO

NOx

PM

HCHO

Tier 1 Standards

LDVs/LDTs (< 3,751 lbs.)

LDTs (3,751-5,750 lbs.)

LDTs (> 5,750 lbs.)

.250

.320

.390

3.4

4.4

5.0

.40

.70

1.10

.08

.08

n/a

n/a

n/a

n/a

.310

.400

.560

4.2

5.5

7.3

.60

.97

1.53

n/a

n/a

n/a

.125/.160

.075/.140

.100/.125

.075

.075

.075

n/a

n/a

n/a

n/a

n/a

n/a

n/a

3.4/4.4

3.4

3.4

3.4

3.4

3.4

n/a

n/a

n/a

n/a

n/a

n/a

n/a

.40

.20

.14

.11

.08

.05

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a .015/.018

.015

n/a

.015

n/a

.015

n/a

.015

n/a

.015

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

.280

.156/.230

.090/.180

.125/.156

.090

.090

.090

.070

.055

.010

.000

n/a

n/a

7.3

4.2/6.4

4.2

4.2

4.2

4.2

4.2

2.1

2.1

2.1

0.0

.07

.20/.30

.90

.60

.30

.20

.15

.10

.07

.04

.03

.02

.00

.10

.10

.12

n/a

n/a

n/a

Tier 2 Standards

Final Fleet Average c

Interim Fleet Averages d

Interim Bin 11 e

Interim Bin 10 f, g

Interim Bin 9 f, g

Bin 8 g

Bin 7

Bin 6

Bin 5

Bin 4

Bin 3

Bin 2

Bin 1

n/a

n/a

n/a

n/a

.032

.12

.08 .018/.027

.018

.06

.018

.02

.018

.02

.018

.01

.018

.01

.011

.01

.011

.01

.004

.01

.000

.00

a

The intermediate useful life standards set a benchmark for the amount of pollutants that a vehicle is expected to emit after being driven

for 50,000 miles. The Tier 1 full useful life standards reflect the amount of pollutants that a vehicle is expected to emit after 100,000

miles of vehicle use. The Tier 2 standards increase the full useful life benchmark to 120,000 miles. If a manufacturer voluntarily chooses

to certify a vehicle to a higher useful life of 150,000 miles, compliance with the Tier 2 intermediate standards is optional.

b

Tier 1 vehicles are subject to the testing procedure for NMHC, but Tier 2 vehicles will be subject to the testing procedure for NMOG.

Both pollutants are closely related hydrocarbon compounds that can combine with NOx in the presence of sunlight to form ground-level

ozone pollution. EPA selected the NMOG testing procedure under Tier 2 because it more accurately measures hydrocarbon levels.

c

Each manufacturer will have the flexibility to select any set, or “bin”, of emission standards when certifying different models of vehicles,

as long as it meets the fleet average requirement for NOx emissions.

d

During the phase-in period, the interim fleet average for LDVs and LLDTs will be .30 grams/mile and will expire at the end of

MY2006. The interim fleet average will be .20 grams/mile for HLDTs and MDPVs and will expire at the end of MY2008.

e

Bin 11 will only apply to MDPVs and will expire at the end of MY2008 when phase-in is complete.

f

Bins 9 and 10 will expire at the end of MY2006 for LDVs and LLDTs and at the end of MY2008 for HLDTs and MDPVs.

g

The higher values will apply only to HLDTs during the phase-in period and will expire at the end of MY2008.

LDV = light duty vehicle (<6,001 lbs.)

LLDT = (light) light duty truck (<6,001 lbs.)

HLDT = (heavy) light duty truck (6,001-8,500 lbs.)

MDPV = medium duty passenger vehicle (8,501-10,000 lbs.)

NMHC = non-methane hydrocarbons

NMOG = non-methane organic gases

CO = carbon monoxide

NOx = nitrogen oxides

PM = particulate matter

HCHO = formaldehyde

Prepared by the Congressional Research Service based on data from the Environmental Protection Agency.

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