The MTBE air concentrations in the cabin of automobiles while fueling

Methyl tertiary-butyl ether (MTBE) is the most commonly used oxygenated com pound added to gasoline to reduce ambient carbon monoxide levels. Complaint s about perceived MTBE exposures and adverse health symptoms have been regi stered in several states, including New Jersey (NJ). Fueling automobiles is the activity thought to cause the highest environmental MTBE exposures. Th e current study was conducted to determine the MTBE concentrations inside a utomobile cabins during fueling, which represents the peak exposure that ca n occur at full service gasoline service stations, such as those that exist in NJ. Air samples were collected at service stations located on the NJ an d PA turnpikes from March 1996 to July 1997 during which the MTBE content i n gasoline varied. A bimodal distribution of MTBE concentrations was found in the cabin of the cars while fueling. The median MTBE, benzene and toluen e in cabin concentrations were 100, 5.5 and 18 ppb, respectively, with the upper concentrations of the distribution exceeding 1 ppm for MTBE and 0.1 p pm for benzene and toluene. The highest in cabin concentrations occurred in a car that had a malfunctioning vapor recovery system and in a series of c ars sampled on an unusually warm, calm winter day when the fuel volatility was high, the evaporation maximal and the dispersion by wind minimal. The i n-cabin concentrations were typically higher when the car window was opened during the entire fueling process. Thus, exposure to MTBE during fueling c an be reduced by properly maintaining the integrity of the fuel system and keeping the windows closed during fueling.