Mobile Sources

Mobile Sources in the United States

Mobile Sources in Environmental Law

This term includes motor vehicles and aircraft that are regulated as pollution sources under the Clean Air Act. Mobile sources contribute carbon monoxide, hydrocarbons, nitrogen oxides, and particulate pollution to the air. Before unleaded gasoline was introduced, they also emitted lead.

Environmental regulation of mobile sources began as early as 1955, but only small steps were taken until the 1970 Clean Air Act was passed, giving the Environmental Protection Agency (EPA) the power to set standards for emissions for new automobiles and to regulate fuels. The Clean Air Act forced automobile manufacturers to develop emission controls and fuel efficiency for cars before the technology for them existed. The deadline for compliance was 1975, a deadline the manufacturers did not meet. When the act was amended in 1977, more realistic standards were set. The goals were not abandoned, but the deadlines were extended.

Today, the federal government controls many aspects of mobile sources: cold start carbon monoxide emissions, vapor recovery systems, emission control devices and diagnostic equipment, and testing of vehicles both before they are marketed and after they have been purchased. Other issues closely related to mobile sources involve fueling, such as fuel additives, vapor recovery from gasoline nozzles, and reformulated or oxygenated gas.

Fine-tuning mobile sources and fuels has greatly reduced air contamination. Still, many areas of the country remain out of compliance with the National Ambient Air Quality Standards for ozone, nitrogen oxides, carbon monoxide, and particulates. Mobile sources contribute large percentages of the total for all of these pollutants.

As a result, the Clean Air Act Amendments of 1990 focused not only on motor vehicles but on their use. Congress envisioned the vehicle owner playing a significant role in creating clean air. Methods of control include periodic inspections of the emission control equipment and vapor recovery systems at gasoline stations. Transportation control measures, such as driving restrictions and special lanes for carpools, have become necessary in some places. Large employers and business owners in major metropolitan areas often must develop and implement a plan to reduce the number of cars being driven to work during peak business hours. Many businesses that own ten or more vehicles must phase in fleet vehicles that run on cleaner fuels. See also nonattainment areas.

California is required to operate a pilot program to reduce emissions from mobile sources within the state. By 1996,150,000 vehicles sold must be capable of running on clean fuel. The number doubles by 1999. Other areas of the country were allowed to opt into the program, but they are not required to do so.
Based on “Environment and the Law. A Dictionary”.



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