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Exposure assessments were conducted aboard diesel locomotives. Results were evaluated to determine variables that affect exposure to DPM (diesel particulate matter) and to assess use of EC (elemental carbon) and OC (organic carbon) as surrogates for DPM. National Institute for Occupational Safety and Health Method 5040 was used for collection and analysis of samples in locomotives and in nonrailroad settings. The level of EC, but not OC, in locomotives was found to be significantly affected by position of exhaust stacks and windows. EC ranged from <1 to 45 (mu)g/m^sub 3^ with a geometric mean (GM) of 3.7 (mu)g/m^sub 3^ and OC ranged from 4 to 4570 (mu)g/m^sup 3^ with a GM of 36.3 (mu)g/m^sup 3^. Background measurements of EC ranged from <1 to 8 (mu)g/m^sup 3^ and OC levels were 4 to 84 (mu)g/m^sup 3^. This study confirms that train crew exposure to DPM is much lower than exposures for miners, is comparable to background urban exposures, and is lower than but comparable to exposures for truck drivers. It also indicates that EC levels are highly predictive of diesel exhaust exposure whereas OC levels are not, and that open windows and exhaust stacks) in front of the locomotive cab have a significant effect on EC.
Keywords: diesel exhaust, elemental carbon, organic carbon, railroad
Since the late 1950s essentially all locomotives in railroad freight service have been diesel powered. The current fleet consists of approximately 22,000 locomotives ranging in size from 1500 to 6000 horsepower that are manufactured principally by General Electric (GE) and the Electro-Motive Division (EMD) of General Motors. Historically, all EMD locomotives have used two 2-cycle engines, whereas GE used a four-cycle engine.(1) Both manufacturers use the diesel engine to power electric drive motors.
Diesel exhaust is a complex mixture of gases, vapors, and particulates. Constituents have been reported to include carbon monoxide; carbon dioxide; sulfur dioxide; nitrogen oxides; benzene; 1,3-butadiene; various aldehydes; and polynuclear aromatic hydrocarbons.(2) Diesel particulate (soot) consists of an elemental carbon (EC) core comprising 60-70% of the particle, onto which other material may be adsorbed. Diesel particulates are less than 1 lim aerodynamic diameter in size and tend to form chains or clusters.(3,4) Estimates of the number of different compounds generated by a diesel engine that can...