Bitumen, polycyclic aromatic hydrocarbons and vehicle exhaust: exposure levels and controls among Norwegian asphalt workers.

OBJECTIVES To characterize exposures of asphalt workers in Norway and to evaluate exposure control measures. METHODS Representative asphalt paving and mixing operations were monitored in Norway in 1991-92 for exposures to bitumen fume, organic vapor, polycyclic aromatic hydrocarbons (PAHs) and vehicle exhaust (NO2, CO). Linear regression was used to evaluate introduced control measures. RESULTS A total of 320 samples of airborne organic matter were gathered (279 from paving). Median personal bitumen fume measurements ranged from 0.03 to 0.15 mg/m3 and were similar in paving and asphalt mixing. According to principal component analysis, there were three independent sets of PAHs: (i) PAHs lighter than 228 g/mol; (ii) 4- to 6-ring PAHs non-detectable in 80-90% of samples; and (iii) naphthalene. Some NO2 (1/49) and CO (12/58) concentrations near paving equipment exceeded 15 min exposure limits, 2 and 25 p.p.m., respectively. Changing sampling methods midway through the study had a significant impact on the measured bitumen fume and organic vapor levels. For pavers, lower application temperatures reduced organic vapor, but not bitumen fume, exposures. Retrofitting a paving machine produced at least a 5-fold reduction in exposure to airborne organic matter. Work in tunnels increased PAH exposures, but general ventilation partially counteracted this effect. CONCLUSIONS The observed exposure levels indicate that some potentially hazardous exposures may have occurred during paving in Norway. Bitumen fume, organic vapor and PAH exposures can be reduced using appropriate engineering control measures.