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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 gasoline is burned (carbon monoxide, nitrogen oxides, particulate matter, and unburned hydrocarbons) contribute to air pollution. Burning gasoline also produces carbon dioxide, a greenhouse gas.

Did you know?

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

In 2017, total U.S. carbon dioxide emissions from aviation and motor gasoline combustion were about 1,142 million metric tons, or about 22% of total U.S. energy-related carbon dioxide emissions.

Laws like the Clean Air Act reduce environmental effects

The United States used about 392 million gallons of gasoline per day in 2017. Most consumers use gasoline in cars, light trucks, and motorcycles, but they also use it in small aircraft, boats and other watercraft, and landscaping and construction equipment. Some of the environmental laws in the United States focus on reducing pollution from these sources.

The Clean Air Act (the Act) seeks to reduce air pollution in the United States. Specifically, the Act (first passed in 1970) and its amendments require engines and fuels to produce less air pollution, among other requirements, to reduce air pollution from gasoline use.1 To meet the air pollution reduction goals of the Act, the U.S. Environmental Protection Agency (EPA) took several actions:

  • 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 non-road equipment.2
  • 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 emissions 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 1996.
  • Required the use of reformulated gasoline
    Beginning in 1995, the Clean Air Act Amendments of 1990 required cleaner burning reformulated gasoline to reduce air pollution in metropolitan areas that had significant ground-level ozone pollution.
  • Required the supply of ultra-low sulfur gasoline
    As of January 1, 2017, refiners are required to supply gasoline with 97% less sulfur content than the gasoline made in 2004. Gasoline with lower sulfur content reduces emissions from old and new vehicles and is necessary for advanced vehicle emission control devices to work properly.
  • Reduced the 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 tanks where they can't be seen.3 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, Transportation: Mobile Sources.

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

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

Last updated: August 28, 2018

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

A combination of health and environmental concerns led to a ban on the sale of leaded gasoline for most uses in the United States.

Did you know?

Mid-grade gasoline was introduced in 1986 as the United States began phasing out leaded gasoline. Most gasoline stations already had pumps for leaded, unleaded, and unleaded premium (also called high-test) gasoline.

Because leaded gasoline use was in decline, mid-grade gasoline was offered as an additional choice for motorists who wanted a higher octane gasoline than regular unleaded. Offering mid-grade gasoline was also a way to continue using all three pumps to sell three grades of gasoline.

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.

The U.S. 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 ways to reduce emissions such as developing catalytic converters, which convert harmful emissions into water, carbon dioxide, and nitrogen gas. Leaded gasoline damages 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 updated: January 2, 2019