Ambient and Emission Trends of Toxic Air Contaminants in California.
After initiating a toxic air contaminant (TAC) identification and control program in 1984, the California Air Resources Board adopted regulations to reduce TAC emissions from cars, trucks, stationary sources, and consumer products. This study quantifies ambient concentration and emission trends for the period 1990-2012 for seven TACs that are responsible for most of the known cancer risk associated with airborne exposure in California. Of these seven, diesel particulate matter (DPM) is the most important; however DPM is not measured directly. Based on a novel surrogate method, DPM concentrations declined 68%, even though the state's population increased 31%, diesel vehicle-miles-traveled increased 81%, and the gross state product (GSP) increased 74%. Based on monitoring data, concentrations of benzene, 1,3-butadiene, perchloroethylene, and hexavalent chromium declined 88-94%. Also, the ambient and emissions trends for each of these four TACs were similar. Furthermore, these declines generally occurred earlier in California than elsewhere. However, formaldehyde and acetaldehyde, which are formed in the air photochemically from volatile organic compounds (VOCs), declined only 20-21%. The collective cancer risk from exposure to these seven reviewed TACs declined 76%. Significant reduction in cancer risk to California residents from implementation of air toxics controls (especially for DPM) is expected to continue.
California Air Resources Board, 1001 "I" Street, P.O. Box 2815, Sacramento, California 95812, United States.
Ralph
R
Propper
California Air Resources Board, 1001 "I" Street, P.O. Box 2815, Sacramento, California 95812, United States.
Patrick
P
Wong
California Air Resources Board, 1001 "I" Street, P.O. Box 2815, Sacramento, California 95812, United States.
Son
S
Bui
California Air Resources Board, 1001 "I" Street, P.O. Box 2815, Sacramento, California 95812, United States.
Jeff
J
Austin
California Air Resources Board, 1001 "I" Street, P.O. Box 2815, Sacramento, California 95812, United States.
William
W
Vance
California Air Resources Board, 1001 "I" Street, P.O. Box 2815, Sacramento, California 95812, United States.
Álvaro
Á
Alvarado
California Air Resources Board, 1001 "I" Street, P.O. Box 2815, Sacramento, California 95812, United States.
Bart
B
Croes
California Air Resources Board, 1001 "I" Street, P.O. Box 2815, Sacramento, California 95812, United States.
Dongmin
D
Luo
D000393:Air Pollutants / Q000032:analysis* / Q000633:toxicity*; D002140:California; D004784:Environmental Monitoring; D006801:Humans; D009369:Neoplasms / Q000209:etiology; D052638:Particulate Matter / Q000032:analysis; D018570:Risk Assessment; D055549:Volatile Organic Compounds / Q000032:analysis
D000393:Air Pollutants; D052638:Particulate Matter; D055549:Volatile Organic Compounds