This series of maps shows statewide trends in estimated inhalable cancer risk from estimated air toxic emissions between 1990 and 2010. The maps show the decline in risk as a result of air pollution controls that are in place in California. The estimates represent the number of potential cancers per million people, based on a lifetime of breathing air toxics. The cut point of 250 cancers per million was selected only because it conveniently illustrates the trends associated with urban areas. Local maps with additional risk cutpoints can be accessed either by emission category or year. The maps shown on this web site reflect an ongoing effort to provide a picture of relative risk and will be periodically updated as additional data become available.

The ARB is publicly releasing the maps on this web site showing estimated outdoor inhalation cancer health risk on a regional basis, using the best available scientific methodologies, and noting the limitations and uncertainty associated with the data and methodologies.

The above map and the other inhalation cancer risk maps available on this web site were produced by ARB staff using the Assessment System for Population Exposure Nationwide (ASPEN) dispersion model. This is the same model used in the United States Environmental Protection Agency's (U.S.EPA's) National Air Toxics Assessment (NATA) study. The ASPEN model's use in the NATA study was reviewed by the U.S.EPA's Science Advisory Board, and the U.S.EPA has released the science advisory resulting from that review. The ASPEN model as implemented by both the ARB and USEPA generally shows lower toxics concentrations when compared to air toxics monitoring data. To look at actual measured air pollution in your neighborhood, go to the ARB's air quality data page.

These risk maps depict inhalation cancer risk due to modeled outdoor toxic pollutant levels, and do not account for cancer risk due to other types of exposure. The largest contributors to inhalation cancer risk are diesel engines. The goal of ARB's Diesel Risk Reduction Plan is to reduce diesel emissions by 75% from the year 2000 levels.