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Gasoline and the Environment

Gasoline use contributes to air pollution

Gasoline is a toxic and highly flammable liquid. The vapors given off when gasoline evaporates and the substances produced when it is burned (carbon monoxide, nitrogen oxides, particulate matter, and unburned hydrocarbons) contribute to air pollution. Burning gasoline also produces carbon dioxide, a greenhouse gas linked to global climate change.1

Did you know?

Burning a gallon of gasoline (that does not contain ethanol) produces about 19.6 pounds of carbon dioxide.

In 2014, total U.S. carbon dioxide emissions from gasoline combustion were about 1,077 million metric tons, approximately 20% of total U.S. energy-related carbon dioxide emissions.

Laws like the Clean Air Act reduce environmental impacts

Americans used about 375 million gallons of gasoline per day in 2014. Most gasoline is used in cars, light trucks, and motorcycles, but it is also used in small aircraft, boats, and water craft, and in landscaping and construction equipment. Reducing pollution from these sources has been a focus of environmental laws in the United States.

The Clean Air Act is a law that seeks to reduce air pollution in the United States. The Clean Air Act (first passed in 1970) and its amendments have aimed to reduce pollution from gasoline use by requiring the use of less polluting engines and fuels2, among other items. To meet its goals, the U.S. Environmental Protection Agency (EPA) implemented several changes following the passage of the act:

  • Required emissions control devices and cleaner burning engines—Emissions control devices on passenger vehicles were required beginning in 1976. In the 1990s, the EPA established emissions standards for other types of vehicles and for engines used in gasoline-burning off road equipment.
  • Removed leaded gasoline—Lead in gasoline proved to be a public health concern. The move away from leaded gasoline began in 1976 when catalytic converters were installed in new vehicles to reduce the emission of toxic air pollutants. Vehicles equipped with a catalytic converter cannot operate on leaded gasoline because the presence of lead in the fuel damages the catalytic converter. Leaded gasoline was completely phased out of the U.S. fuel system by 1986.
  • Required the use of reformulated gasoline—Beginning in 1995, the Clean Air Act Amendments of 1990 required the use of cleaner burning reformulated gasoline to reduce air pollution in metropolitan areas that had significant ground-level ozone pollution.
  • Required the supply of low-sulfur gasoline—Since 2006, refiners have been required to supply gasoline with 90% less sulfur content than they made in 2004. More reductions in gasoline sulfur content are planned to begin in 2017. Gasoline with lower sulfur content reduces emissions from old and new vehicles, and it is necessary for advanced vehicle emission control devices to work properly.
  • Reduced risk of gasoline leaks—Gasoline leaks happen at gas stations every day. As people fill up their gas tanks, gasoline drips from the nozzle onto the ground and vapors leak from the open gas tank into the air. Gasoline leaks can also happen in pipelines or in underground storage tanks4 where they can't be seen. Beginning in 1990, all underground storage tanks had to be replaced by tanks with double lining. The double lining provides an additional safeguard for preventing leaks.

Methyl tertiary butyl ether (MTBE), one of the chemicals added to gasoline to help it burn cleaner, is toxic, and a number of states started banning the use of MTBE in gasoline in the late 1990s. By 2007, the U.S. refining industry had voluntarily stopped using MTBE when making reformulated gasoline for sale in the United States. MTBE was replaced with ethanol, which is not toxic.

1. U.S. Environmental Protection Agency, Climate Change Science.

2. U.S. Environmental Protection Agency, Transportation: Mobile Sources.

3. U.S. Environmental Protection Agency, Nonroad Engines, Equipment, and Vehicles.

4. U.S. Environmental Protection Agency, Underground Storage Tanks.

Last reviewed: December 15, 2015

Leaded gasoline was gradually taken off the U.S. market

A combination of health and environmental concerns led to the elimination of leaded gasoline.

Did you know?

Mid-grade gasoline was introduced in 1986 as leaded gasoline was being phased out. Most gas stations already had pumps for leaded, unleaded, and unleaded premium (also called high-test) gasoline.

Leaded gasoline use was in decline, so mid-grade gasoline was offered as an additional choice for motorists who wanted a higher octane gas than regular unleaded. Offering mid-grade gasoline was also a way to solve the problem of having three pumps and only two types of gas.

Health hazards associated with lead have been documented since the early 1920s. The U.S. Surgeon General set a voluntary standard for lead content in leaded gasoline. The standard was raised in the 1950s.

Congress adopted the Clean Air Act in 1970 and created the U.S. Environmental Protection Agency (EPA). The Clean Air Act set air quality standards that included a timetable for phasing out leaded gasoline.

The Clean Air Act also regulated automobile emissions of carbon monoxide, nitrogen oxides, and hydrocarbons for the first time. The automobile industry responded to these new standards by devising methods to reduce emissions to include developing catalytic converters, which convert harmful emissions into water, carbon dioxide, and nitrogen gas. Leaded gasoline actually damaged the new catalytic converters.

By 1975, unleaded gasoline was universally available. Effective January 1, 1996, leaded gasoline was banned by the Clean Air Act for use in new vehicles other than aircraft, racing cars, farm equipment, and marine engines.

Last reviewed: December 1, 2015