MATES III Fact Sheet

The South Coast Air Quality Management District is currently involved in an intensive study to assess current levels of cancer-causing toxic air pollutants and the risk they pose to Southland residents.

This wide ranging and comprehensive air sampling program, called the Multiple Air Toxics Exposure Study III (MATES III), began in April 2004 and is expected to conclude in early March 2006. The study, originally slated for one year, was extended for an additional year due to near-record rainfall this past winter and its potential effects on the pollutant levels being monitored. This study follows the landmark MATES II, conducted in 1998-1999, and the seminal MATES, run in 1986-1987.

The goal of MATES III is to update toxic air pollution levels and toxic emission inventories, and then input those data into a computer model of air dispersion to determine the cancer risk, as well as non-cancer health risk, from air toxics across the Southland. The study also investigates potential toxic “hot spots” in communities.

Compounds Monitored

MATES III is monitoring for 21 toxic air contaminants and four other substances at 10 sites across the Los Angeles Basin (see lists below). In addition, AQMD is utilizing mobile monitoring stations to sample at several 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. Sampling at each neighborhood site will last up to three months.

During MATES III, AQMD will double the sampling frequency of the previous study from one-in-every-six days to one-in-three. In addition to the most significant pollutants sampled in MATES II, the current study also includes limited sampling for naphthalene, a combustion by-product that may pose a significant health hazard according to current assessments by environmental agencies and academic researchers.

AQMD scientists have convened a Technical Advisory Group, including representatives of other environmental agencies, universities, industry and environmental groups. The committee is providing guidance throughout the duration of the study and has assisted in selecting specific neighborhood monitoring sites.

Toxic Air Contaminants Monitored in MATES III

1,3-Butadiene
Acetaldehyde
Arsenic
Benzene
Beryllium
Cadmium
Carbon Tetrachloride
Chloroform
Elemental Carbon
Formaldehyde
Hexavalent Chromium
Lead
Manganese
Methylene Chloride
Naphthalene
Nickel
Perchloroethylene
Polycyclic Aromatic Hydrocarbons (PAHs)
Propylene Dichloride
Trichloroethylene
Vinyl Chloride

AQMD’s Governing Board has placed a high priority on reducing toxic air pollution and resulting health risk. In 2000 and 2001, the Board adopted a series of clean fleet rules to reduce diesel exhaust from transit buses, trash trucks, street sweepers, airport taxis, school buses and other fleets.

AQMD’s Board also has adopted regulations to reduce perchloroethylene from dry cleaners and other industries, and hexavalent chromium from metal plating facilities. In addition, the Board has approved more than $100 million in local and state funding to help replace aging, dirty diesel engines in school buses, marine vessels and other vehicles with lower-emission diesel and alternative fuel models.

MATES II, the nation’s most comprehensive study of toxic air pollution to date, found that:

AQMD is the air pollution control agency for Orange County and major portions of Los Angeles, San Bernardino and Riverside counties.