California's Achievements in Mobile Source Emissions Control

Untitled Document

Since its formation in 1967, the California Air Resources Board (CARB) has successfully launched numerous emissions reduction programs in the state. These programs have significantly improved California’s air quality, despite the number of people and vehicles more than doubling over the past four decades. CARB’s programs have resulted in major advancements in emissions control technologies, which have served as the basis for similar federal programs developed by the U.S. Environmental Protection Agency (EPA). California’s programs remain vital, and CARB has outlined its plans for continuous progress through 2020. This article presents an overview of California’s achievements in mobile source emissions control.


California’s statewide efforts for air pollution control began in 1955 with the formation of the Bureau of Air Sanitation within the state Department of Public Health. California enacted legislation in 1959 that required the Department of Public Health to establish air quality standards and necessary controls for motor vehicle emissions, and in 1960, created the California Motor Vehicle Pollution Control Board to certify emissions control devices for vehicles. Subsequently, under the Federal Air Quality Act of 1967, California was granted a waiver to adopt and enforce its own emissions standards for new vehicles, in recognition of the state's unique air quality need to set more stringent emissions control requirements compared to the rest of the nation.1 Also in 1967, CARB was formed through the Mulford-Carrell Air Resources Act by merging the California Motor Vehicle Pollution Control Board and the Bureau of Air Sanitation. CARB's mission is to promote and protect public health, welfare, and ecological resources through the effective and efficient reduction of air pollutants while recognizing and considering the effects on the state's economy.

Poor Air Quality

California’s geography and the quantity of air contaminants emitted are the main causes of unhealthy air within the state. The most heavily populated areas are valleys or basins hemmed in by mountains. Combined with hot ambient temperatures in the summer and stagnant atmospheric inversion layers (see Figure 1), all the ingredients for poor air quality are prevalent. In 1952, Dr. Arie Haagen-Smit (see Figure 2), a professor at the California Institute of Technology, discovered the nature and causes of photochemical smog that produced poor air quality. He determined that oxides of nitrogen (NOx) and hydrocarbon (HC) emissions in the presence of sunlight created smog, of which ozone is a key component. The agents in this process are byproducts of petroleum fuel combustion. These conclusions were not readily accepted by the automobile industry, however, and it was not until 1954 that general agreement was reached.3 This scientific breakthrough of the formation of ozone led to the development of emissions control regulations that specifically targeted the reduction of HC and NOx emissions. Dr. Haagen-Smit later became the first chairman of CARB in 1968.

Customer comments

No comments were found for California's Achievements in Mobile Source Emissions Control. Be the first to comment!