Airborne Concentrations of Benzene Due to Diesel Locomotive Exhaust in a Roundhouse

Abstract

Concentrations of airborne benzene due to diesel exhaust from a locomotive were measured during a worst-case exposure scenario in a roundhouse. To understand the upper bound human health risk due to benzene, an electromotive diesel and a General Electric four-cycle turbo locomotive were allowed to run for four 30-min intervals during an 8-h workshift in a roundhouse. Full-shift and 1-h airborne concentrations of benzene were measured in the breathing zone of surrogate locomotive repairmen over the 8-h workshift on 2 consecutive days. In addition, carbon monoxide was measured continuously; elemental carbon (surrogate for diesel exhaust) was sampled with full-shift area samples; and nitrogen dioxide/nitric oxide was sampled using full-shift and 15-min (nitrogen dioxide only) area samples. Peak concentrations of carbon monoxide ranged from 22.5 to 93 ppm. The average concentration of elemental carbon for each day of the roundhouse study was 0.0543 and 0.0552 microg/m(3 )for an 8-h workshift. These were considered "worst-case" conditions since the work environment was intolerably irritating to the eyes, nose, and throat. Short-term nitrogen dioxide concentrations ranged from 0.81 to 2.63 ppm during the diesel emission events with the doors closed. One-hour airborne benzene concentrations ranged from 0.001 to 0.015 ppm with 45% of the measurements below the detection limit of 0.002-0.004 ppm. Results indicated that the 8-h time-weighted average for benzene in the roundhouse was approximately 100-fold less than the current threshold limit value (TLV) of 0.5 ppm. These data are consistent with other studies, which have indicated that benzene concentrations due to diesel emissions, even in a confined environment, are quite low.

Exposure to Airborne Asbestos During Removal and Installation of Gaskets and Packings: A Review of Published and Unpublished Studies

“…The simulation studies involve characterizing exposures associated with specific products or worker tasks by reenacting work activities in a contaminant-free environment. These types of studies often provide useful insight as to the extent a particular work activity might contribute to a worker's overall exposure and are preferred over collecting samples at work sites when other worksite sources could confound measurements (Madl & Paustenbach, 2002a, 2002bPaustenbach et al, 2004).…”

Occupational exposure to diesel engine exhaust: A literature review

“…In addition, area levels of visible smoke, the number of detectable NO 2 samples, and peak CO levels were higher in a roundhouse when the doors were shut than when they were open (Madl, et al, 2002). …”

Health risk communication using comparative risk analyses

“…A good example of an intrachemical comparison involves a simulation study of airborne benzene concentrations in a locomotive roundhouse. As part of this study, Madl and Paustenbach (2002) estimated a railroad worker's ''worst-case'' benzene exposure and cumulative dose from diesel exhaust over a 40-year period, and compared these findings to estimated benzene exposure/dose levels from other common sources or activities over this same time period (see Figure 1). Benzene exposure and cumulative dose estimates from inhalation of diesel exhaust (0.18 ppm-years and 1.5 g, respectively) were found to be substantially lower than what would be received from moderate smoking (32 cigarettes per day), and were found to be comparable to living in Los Angeles breathing urban ambient air or refueling at the gas pump for 5 min per week.…”