11 February 2004

The South Coast Air Quality Management District (SCAQMD)—an air pollution control agency in Southern California, including Los Angeles—started a new one-year study to assess levels of cancer-causing toxic air pollutants and the risk they pose to residents of Southern California.

Sampling for all substances in the Multiple Air Toxics Exposure Study III (MATES III) is expected to begin in mid-February. This study follows the MATES II, conducted in 1998-1999, and the MATES, run in 1986-1987.

The SCAQMD said it has reduced cancer-causing emissions through numerous regulations issued since the Mates II project. The MATES III study will shed more light on the effectiveness of these regulations and serve as a tool in shaping future air quality policies.

The goal of MATES III is to update toxic air pollution levels and inventories, and then input those data into a computer model to determine the cancer and non-cancer health risks from air toxics. MATES III will monitor for 21 toxic air contaminants and four other substances at 10 sites across the Los Angeles Basin. In addition, SCAQMD will use moveable monitoring stations to sample at a dozen or more neighborhood sites near toxic emission sources or in areas where community members are concerned about health risks from air pollution. Such neighborhood sites could be near airports, railroads, warehouses, landfills, high-volume vehicle traffic or multiple commercial or industrial facilities.

MATES III monitoring will continue through early 2005. The study is expected to be finished in summer 2005.

The previous MATES II study, which monitored more than 30 toxic air pollutants, included an effort to estimate cancer risk from exposure to diesel particulates. The study identified particulate emissions—attributed mostly to diesel engines—as an important cancer risk factor. According to MATES II, diesel particulates accounted for about 70% of the total cancer risk associated with the investigated group of air pollutants.

Outdoor toxic air pollution accounts for about 0.6% of the total cancer risk in California.

SCAQMD press release