title: Day-of-week patterns in toxic air contaminants in southern California.
abstract: Day-of-week mean ambient concentrations were computed for six high-cancer-risk toxic air contaminants (TACs): 1,3-butadiene, benzene, acetaldehyde, formaldehyde, carbon tetrachloride (CCl4), and perchloroethylene. Data from six urban sites in southern California, from 1989 through 2001, were analyzed. Graphical displays were used to search for repeated patterns. Benzene and 1,3-butadiene, emitted mainly by mobile sources, exhibit distinctly lower concentrations on Sundays and slightly lower concentrations on Saturdays and Wednesdays. Acetaldehyde and formaldehyde show some trace of a weekly pattern similar to that of benzene and 1,3-butadiene, but the pattern is not strongly marked. Perchloroethylene, used primarily as a dry-cleaning solvent, is also distinctly lower on Sundays. CCl4 does not show a day-of-week pattern.
authors.affiliation: Planning and Technical Support Division, California Air Resources Board, Sacramento, California 95812, USA. jaustin@arb.ca.gov
authors.forename: Jeff
authors.initials: J
authors.lastname: Austin
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D002140:California; D002273:Carcinogens / Q000032:analysis*; D004784:Environmental Monitoring; D010083:Oxidants, Photochemical / Q000032:analysis*; D010126:Ozone / Q000032:analysis*; D010507:Periodicity; D012016:Reference Values
chemical_list: D000393:Air Pollutants; D002273:Carcinogens; D010083:Oxidants, Photochemical; D010126:Ozone