The automobile is the largest single source of toxic emissions in urban areas. Vehicle emissions contribute 57 percent of the nitrogen oxides (NO_x) and 82 percent of the carbon monoxide (CO) found in the air of California urban areas, according to a study by the California Air Resources Board. Vehicular exhaust contains Volatile Organic Compounds (VOCs), and VOCs also evaporate into the atmosphere from leaks and spills. Atmospheric NO_x reacts with VOCs in the presence of sunlight and heat to create ozone. Dust from roads is a major contributor to urban particulate pollution. 

Preventing automotive pollution by improving the efficiency of engines, by switching to cleaner burning fuels or by improving traffic flow can significantly reduce urban pollution levels. But increased traffic can negate the resulting reduction in air pollution. The volume of traffic traveling the roads in an urban area must be stabilized or reduced if long-term improvement in air quality is to result. See the Transportation Section of this website for more details. One example of a program that focuses on improving air quality by promoting commuter solutions such as telework, transit and flex time is Atlanta's Clean Air Campaign.

The Clean Air Act requires EPA to set emission standards for new vehicles for CO, NO_x and hydrocarbons. The Act mandates the use of oxygenated fuels to improve combustion efficiency and reduce tailpipe emissions in areas that fail to meet federal pollution standards as the result of automotive pollution. See the Clean Fuels subsection of the Smart Communities Network Transportation Section for details.   

Clean Cities is a voluntary program sponsored by DOE, supporting public-private partnerships that deploy alternative fuel vehicles and build supporting alternative fuel infrastructure.

The Alternative Fuels Data Center is operated by the National Renewable Energy Laboratory with funding and direction from DOE, to provide alternative fuel and vehicle information. Their website includes the Alternative Motor Fuels Act of 1988, a federal statute that encourages the development and widespread use of methanol, ethanol, and natural gas as transportation fuels by consumers and the production of methanol, ethanol, and natural gas powered vehicles. 

The EPA Office of Transportation and Air Quality is responsible for programs designed to control air pollution from mobile sources such as motor vehicles, farm and construction equipment, marine engines, aircraft and locomotives.  

EPA and the U.S. Department of Transportation offer the website, It All Adds Up to Cleaner Air, which includes information on reducing transportation pollution, a community partners initiative, and the Alliance for Clean Air Transportation.

The Clean Car Campaign is coordinated by a number of nonprofit organizations, including the Union of Concerned Scientists. The website includes the Clean Car Pledge, news and information links.

Tailpipe Tally, provided by Environmental Defense, compares the environmental and economic costs of different vehicles with an online calculator.

On-line Articles and Publications 

Fuel Economy Guide: Model Year 2005 is a publication from the U.S. DOE and EPA that ranks vehicles by gas mileage. It is available online and includes a section on alternative fuel vehicles.

Fact Sheets on Alternative Fuels are offered online by U.S. EPA. 

Clearing the Air with Transit Spending, a report from the Sierra Club, links spending on public transportation with improved air quality in metropolitan areas.

Vehicle Buyer's Guide for Fleets, offered by the Clean Cities program, is designed to educate fleet managers and policy makers about alternative fuels and vehicles.

ACEEE's Green Book: The Environmental Guide to Cars & Trucks rates all new vehicles each year according to environmental friendliness.

Reducing Greenhouse Gas Emissions from Light-Duty Motor Vehicles is a comprehensive study by the Northeast States Center for a Clean Air Future, showing that within 5-10 years, motor vehicle GHG emission reductions of up to 47% could be achieved using combinations of technologies that are currently in production or under development worldwide, and that the cuts could be paid for with gas savings.

Clearing the Air, Public Health Threats from Cars and Heavy Duty Vehicles- Why We Need to Protect Federal Clean Air Laws, from the Surface Transportation Policy Project, names transportation as a major contributor to air pollution nationwide. (PDF)

Cars, Not Crops, Should Be Chief Targets in Reducing Greenhouse Gases reports research by Duke ecologists that shows that agricultural ways of keeping carbon dioxide from the atmosphere are far less effective than better fuel economy.

Last updated January 31, 2005

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