| Atmospheric Concentrations | SOURCE DOMINATED: Trace amounts of 2-methyl-1-butene were detected in brush fire smoke Cajon Pass, CA. 2-Methyl-1-butene was also detected in samples from an industrial area of Los Angeles County, CA, a Riverside, CA shopping center parking lot, and a nearby busy intersection with three filling stations. The compound was not detected in smog taken from the University of California Riverside campus(1). Air samples taken downwind from a natural gas facility at Piceance Creek in Rio Blanco County, CO, contained 2-methyl-1-butene at 10.7 ppbC(2). Monitoring data was collected from 6 self-service stations in the US (Cincinnati, OH, Phenoix, AZ, Los Angeles, CA) to assess consumer exposure to airborne gasoline components(3). 2-Methyl-1-butene was detected (detection of quantitation = 3 ug/sample) at a range of 0.02-5.2 mg/cu m(3).URBAN/SUBURBAN: Weekday air samples were taken from 6 to 9 am in 39 US cities during a 1984 through 1986 time period(1). In 822 samples, 2-methyl-1-butene was detected at a median concn of 2.6 ppbC, with a maximum value of 242 ppbC(1). Ambient air from Tulsa, OK contained 2-methyl-1-butene at a range of 0.6-6.4 ppbC(2). During a severe Los Angeles area photochemical smog episode in September 1993, 2-methyl-1-butene was measured in the vapor phase at an average concentration of 1.13 ug/cu m (range not detected to 3.40 ug/cu m)(3). Air samples collected from the industrial area of Houston, TX, contained 2-methyl-1-butene at concentrations of not detected to 53.8, 8.7 to 47.6 and not detected to 3.7 ppbC on separate days in September 1973, January 1974, and April, 1974, respectively (detection limit not reported) (4). Air samples collected by aircraft over Miami in May 1976 contained 2-methyl-1-butene at concentrations of 0.5 and 0.6 ppbC(5). Air samples collected from downtown Los Angeles during morning rush hour, fall 1968, contained 2-methyl-1-butene at 15 ppbC(6). The average concentration of 2-methyl-1-butene in downtown Porto Alegre, Brazil over the period March 1996 to April 1997 is 4.4 mg/cu m (n=46)(7). Concentrations of 2-methyl-1-butene inside and outside the town of Boone, NC (university town, little industry) from September 1981 to October 1982 ranged from 1.5 to 3.7 and 0.3 to 0.5 ppbC, respectively(8). The average concentration of 2-methyl-1-butene is 0.5 ppbv (0.5 weight %n=140) in the morning air of Sydney, 30 day monitoring period at 3 different sampling sites (1 downwind of central business district, 2 sites downwind of a refinery-petrochemical complex)(9). 2-Methyl-1-butene was present at 2.0 ppb in ambient air samples collected at the Riverside CA County Building of Health and Finance between August 1965 and March 1966 in the early morning(10). The mean concentration of 2-methyl-1-butene measured between 6 and 9 am during the summers of 1984 to 1RURAL/REMOTE: 2-Methyl-1-butene was detected in the ambient air of Sevier County, TN in the Great Smokey Mountains National Park, ranging from not detected to 1.1 ppbC(1). Air samples collected in the remote Piceance Creek Basin, Colorado contained 2-methyl-1-butene at concentrations from 0.4 to 1.2 ppbC(1). The concentration of 2-methyl-1-butene in air samples collected above a mixed deciduous forest in southern Ontario, Canada in 1993 was 0.002 and 0.003 ppbv in day and nighttime samples, respectively(2). 2-Methyl-1-butene was measured at 0.3 and 0.4 ppbC in ground level air samples collected in an orange grove during May near Dunedin, FL(3). An average 2-methyl-1-butene concentration of 0.2 mg/cu m was measured 30 km southeast of Porto Alegre, Brazil (upwind of the city during sample collection) in November 1996(4). Concentrations of 2-methyl-1-butene at 5 remote locations in the southern Appalachian Mountains of northwestern North Carolina from September 1981 to October 1982 ranged from not detected to 0.4 ppbC(5). 2-Methyl-1-butene was measured in air samples at concentrations from 0.2 to 3.2 ppbC collected from a picnic area at Jones State Forest between January 4 to 6, 1978(6). |
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