The development and chronology of autmobile emissions reductions efforts in the United States

Automobile Emissions Reduction Efforts in the U.S. - Chronology

Back to the Table of Contents page for information on many other subjects!

horizontal rule

United States Environmental Protection Agency
Air and Radiation
Office of Mobile Sources
EPA420-F-99-017
May 1999

NOTE: The on-line version of this document has been provided for your convenience, although it does not meet EPA graphic standards. Please see the Adobe Acrobat Portable Document Format (PDF) version or the original for the correct formatting and layout. The information is unchanged from the original.

horizontal rule

Emission Facts

The History of Reducing Tailpipe Emissions

1970-1975: The First Standards In 1970, Congress passes the Clean Air Act, which called for the first tailpipe emissions standards. The pollutants controlled are carbon monoxide (CO), volatile organic compounds (VOC), and oxides of nitrogen (NOx). The new standards go into effect in 1975 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 amends the Clean Air Act and tightens emission standards again in two steps. First, between 1977 and 1979, the NOx standard becomes 2.0 gpm for cars. Then in 1981, the NOx standard for cars is reduced to 1.0 gpm. Effective in 1979, pursuant to the Clean Air Act requirements, EPA tightens standards for light-duty trucks to 2.3 gpm. Effective in 1988, EPA then sets the first tailpipe standards for heavier trucks at 1.7 gpm and revises the standard for lighter trucks to 1.2 gpm.

1990-1994: Tier 1 In 1990, Congress again amends the Clean Air Act, further tightening emission standards. The NOx standard is set at 0.6 gpm for cars, effective in 1994. The new standard called "Tier 1"is a 40 percent reduction from the 1981 standard. For trucks, the new standard ranges from 0.6 to 1.53 gpm, depending on the weight of the vehicle.

The Clean Air Act Amendments of 1990 also require 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 with the auto industry and the Northeast states strike 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 reach consumers in New England in 1999 and will reach the rest of the country in 2001. NLEV cars operate with a NOx standard of 0.3 gpm, a 50 percent reduction from Tier 1 standards. The NLEV agreement also calls for a 0.5 gpm NOx standard for lighter 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 issues the Tier 2 Report to Congress. The report contains strong evidence of the need, cost-effectiveness and feasibility for tighter tailpipe emission standards in the future beginning in 2004. Three main factors support EPA's decision:

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

2) larger vehicles like SUVs, that currently do not meet the same standards as cars, pollute 3-5 times as much and make up 50 percent of the vehicles sold today; and

3) the technology to meet tighter standards is available and cost-effective.

In 1998, EPA also determines that sulfur reductions in gasoline are needed to enable the full performance of low emission-control devices.

1999: Tier 2 In 1999, EPA proposes Tier 2 tailpipe emissions standards beginning in 2004the first time both cars and light-duty trucks are subject to the same national pollution control system. The new standard is 0.07 gpm for NOx, a 77-86 percent reduction for cars and a 92-95 percent reduction for trucks beyond the NLEV agreement. EPA also proposes a reduction in average sulfur levels to 30 parts per million (ppm) (maximum of 80 ppm) to achieve the full performance of vehicle emission control technologies.

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

  • allowing averaging to meet both the car emission and gasoline sulfur standards;
  • allowing extra time for larger vehicles between 6000 and 8500 pounds and smaller 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
Year 1975 1977 1981 1994 1999 2004-2009
NOx Standard (gpm) 3.1 2.0 1.0 0.6 0.3 0.07
NOx Reduced (from previous standard
35% 50% 40% 50% 77%

Smaller SUVs, Minivans, and Light Trucks (Less that 6000 lbs)

Year 1975 1979 1988 1994 1999 2004-2009
NOx Standard (gpm) 3.1 2.3 1.2 0.6 0.5 0.07
NOx Reduced (from previous standard
26% 48% 50% 17% 86%

Larger SUVs, Vans, and Heavier Trucks (Between 6000 and 8500 lbs)

Year 1988 1994 2004-2007 2008-2009
NOx Standard (gpm) 1.7 1.53 0.2 0.07
NOx Reduced (from previous standard
10% 87% 65% or 95% from 1994 standard

For More Information

Document information is also available by writing to:

Tier 2 Team
U.S. Environmental Protection Agency
Office of Mobile Sources
2000 Traverwood Drive
Ann Arbor, MI 48105

horizontal rule

Ways to save money AND help the environment:

Eat healthier AND save money: Instant Pot Duo Crisp 11-in-1 Air Fryer and Electric Pressure Cooker Combo with Multicooker Lids that Fries, Steams, Slow Cooks, Sautés, Dehydrates

Save water AND money with this showerhead adapter, it lets the water flow until the water is hot, then shuts off water flow until you restart it, ShowerStart TSV Hot Water Standby Adapter

Protect your health with these:

Mattress Dust mite-Bedbug protector, 100% Waterproof, Hypoallergenic, Zippered

Handheld Allergen Vacuum Cleaner with UV Sanitizing and Heating for Allergies and Pet, Kills Mite, Virus, Molds, True HEPA with Powerful Suction removes Hair, Dander, Pollen, Dust,

Immune Support Supplement with Quercetin, Vitamin C, Zinc, Vitamin D3

GermGuardian Air Purifier with UV-C Light and HEPA 13 Filter, Removes 99.97% of Pollutants

5 Stage Air Purifier, Features Ultraviolet Light (UVC), H13 True Hepa, Carbon, PCO, Smart Wifi, Auto Mode, Quiet, Removes 99.97% of Particles, Smoke, Mold, Pet Dander, Dust, Odors

Interesting Reads:

THE PREPPER'S CANNING & PRESERVING BIBLE: [13 in 1] Your Path to Food Self-Sufficiency. Canning, Dehydrating, Fermenting, Pickling & More, Plus The Food Preservation Calendar for a Sustainable Pantry

The Backyard Homestead: Produce all the food you need on just a quarter acre! Paperback

The Citizens' Guide to Geologic Hazards: A Guide to Understanding Geologic Hazards Including Asbestos, Radon, Swelling Soils, Earthquakes, Volcanoes

The Uninhabitable Earth: Life After Warming

Book: The Sixth Extinction: An Unnatural History Paperback




See Echo Dot on Amazon