As emissions from passenger cars are reduced, emissions from vehicle refueling, fuel transportation, processing, and feedstock extraction represent a larger share of the total emissions that are attributed to vehicle operation. Quantifying these fuel-cycle emissions is an important aspect of assessing the total emissions impact of vehicle operation. This project builds upon the 1996 ARB study, “Evaluation of Fuel-Cycle Emissions on a Reactivity Basis” (Unnasch 1996), with the purpose of examining uncertainties and further document assumptions.
Although significant strides have been made toward improving California’s air quality, health-based state and federal air quality standards continued to be exceeded in regions throughout California. Areas exceeding the federal 1-hour ozone standard include the South Coast Air Basin (SoCAB), San Diego County, San Joaquin Valley, the Southeast Desert, the Broader Sacramento area, and Ventura County. With promulgation of the new federal 8-hour ozone standard, more areas of the State are likely to be designated as nonattainment. Ozone (created by the photochemical reaction of reactive organic gases (ROG) and oxides of nitrogen (NOx)) leads to harmful respiratory effects including lung damage, chest pain, coughing, and shortness of breath, especially affecting children and persons with compromised respiratory systems. Other environmental effects from ozone include crop damage. In addition, because ozone precursors, such as NOx, also react in the atmosphere to form particulate matter (PM), reductions in NOx will be crucial to meet existing state and federal PM10 standards, as well as the new federal standards for fine particulate matter (PM2.5).
California’s plan for achieving the federal 1-hour ozone standard is contained in the California State Implementation Plan (SIP) that was approved by the ARB in 1994. A significant part of the SIP pertains to the control of mobile sources, which are estimated to account for approximately 60 percent of ozone precursors statewide. The SIP calls for new measures to cut ozone precursor emissions from mobile sources to half of what the emissions would be under existing regulations. These measures includes Improved Technologies for Light-Duty Vehicles, which calls for the adoption of technology-based emission control strategies for light-duty vehicles to be implemented beginning with the 2004 model year.
The pressing requirements for meeting air quality attainment goals have brought about amendments to ARB’s Low Emission Vehicle (LEV) standards with the LEV II standards (ARB 1998). The LEV II regulations will help achieve and maintain the federal 1-hour ozone standard in regions such as the San Joaquin Valley and the Sacramento area, the federal 8-hour ozone and particulate matter in a number of areas, and the state ozone and particulate matter standards throughout California.
The LEV II standards include a new emission standard category — Super Ultra Low Emission Vehicle (SULEV) for passenger cars and light trucks. A variety of vehicle