California ARB sued over the identification of diesel PM as a toxic air contaminant

21 January 2000

Industry groups, including California Trucking Association, American Trucking Association, and California Bus Association filed a lawsuit in California state court in San Diego against the California Air Resources Board (ARB), charging the ARB with inappropriate use of scientific data in its identification of diesel particulates as a toxic air contaminant (TAC).

The ARB's decision of August 1998 was based on recommendations by ARB's Scientific Review Panel (SRP) and California Office of Environmental Health Hazard Assessment (OEHHA). California scientists established the carcinogenic character of diesel particulates and calculated unit cancer risks from exposure to ambient levels of diesel exhaust using data from old railroad worker diesel exposure studies. That data was deemed inappropriate for the purpose of quantitative risk assessment from exposure to diesel emissions by scientists from the Health Effects Institute, from the federal EPA's Clean Air Scientific Advisory Committee (CASAC), as well as by the authors of the railroad studies.

In the filed lawsuit the charging groups said the ARB and OEHHA staff selectively manipulated scientific data to support its conclusion of the carcinogenic character of diesel exhaust. The group also stated, the California ARB is not willing to change the TAC classification of diesel particulates, so it can mandate natural gas engines and vehicles, rather than promoting new cleaner diesel technologies. Since natural gas technologies are much more expensive than diesel, the industry is facing high costs associated with the expected mandatory conversions to natural gas engines.

The South Coast Air Quality Management District (SCAQMD) has already used the ARB diesel carcinogenicity guidelines to release a report blaming 71% of lung cancer risk from TACs on diesel exhaust particulates and to propose rules restricting purchases of diesel vehicles.

Source: Hart’s Diesel Fuel News