Assessment of Personal Exposure to Black Carbon and Nitrogen Dioxide in Contrasting Urban (Road Traffic) and Industrial (Fracking) Environments

摘要

Aim: This study used real-time monitors to assess and compare environmental and occupational exposure to black carbon (BC), nitrogen dioxide (NO_2), and ozone (O_3) in contrasting urban and industrial environments. Methods: Pedestrian exposures to traffic-related air pollution in central Glasgow were compared to occupational exposures to diesel engine exhaust from industrial fracking equipment at an experimental hydraulic fracturing (HF) test site in Poland. Mobile measurements at varying distances from sources in both of the above locations were made using portable real-time micro-aethalometers (AE51) for BC and Aeroqual series-500 monitors for NO_2 and O_3 carried by researchers. Duplicate BC measurements were compared with NO2 observations, after correction of the sensor response for the latter for O_3 interference effects. Results: The highest 1-minute average BC concentrations measured at the HF test site were approximately five times higher than equivalent 1-minute average concentrations observed in central Glasgow (51.2 ug/m3 and 10.0 μg/m~3 respectively). Similarly, maximum 1-minute average NO_2 concentrations measured at the HF test site exceeded equivalent 1-min average observations in Glasgow (292.3 μg/m~3 and 108.1 μg/m~3 respectively). The overall BC mean exposure on roadside walking routes in Glasgow was higher than the overall mean exposure observed across multiple locations, upwind and downwind of diesel engine sources, at the HF test site (2.0 μg/m~3 and 1.6 μg/m~3respectively). Mean NO2 concentrations across Glasgow central roadside locations (64.7 μg/m~3) was also higher than overall mean occupational exposure to NO_2 at the HF test site (43.9 μg/m~3). Duplicate BC instruments provided very similar real-time measurements, which in turn were relatively highly correlated with NO_2 observations at 1 -minute temporal resolution at the HF experimental site (R~2 = 0.65) and the central Glasgow walking route (R~2 = 0.88). Conclusion: Marked elevations of BC and NO_2 concentrations were observed in downwind proximity to traffic and industrial fracking equipment sources. Exposure to diesel engine exhaust emissions from fracking equipment may present a significant risk to people working on HF sites over extended time periods. The short time resolution of the portable instruments used, enabled identification of sources of occupational and environmental exposure to combustion-related air pollutants.