Modeling population exposure to community noise and air pollution in a large metropolitan area

Epidemiologic studies have shown that both air pollution and community noise are associated with cardiovascular disease mortality. Because road traffic is a major contributor to these environmental pollutants in metropolitan areas, it is plausible that the observed associations may be confounded by coexistent pollutants. As part of a large population-based cohort study to address this concern, we used a noise prediction model to assess annual average community noise levels from transportation sources in metropolitan Vancouver, Canada. The modeled annual average noise level was 64 (inter quartile range 60-68) dB(A) for the region. This model was evaluated by comparing modeled annual daytime A-weighted equivalent continuous noise levels (L-day) with measured 5-min daytime A-weighted equivalent continuous noise levels (L-eq.day.5 min) at 103 selected roadside sites in the study region. On average, L-day was 6.2 (95% Cl, 6.0-7.9) dB(A) higher than, but highly correlated (r=0.62; 95% Cl, 0.48-0.72) with, L-eq.day.5 min. These results suggest that our model-based noise exposure assessment could approximately reflect actual noise exposure in the study region. Overall, modeled noise levels were not strongly correlated with land use regression estimates of traffic-related air pollutants including black carbon, particulate matter with aerodynamic diameter <= 2.5 mu m (PM2.5), NO2 and NO; the highest correlation was with black carbon (r=0.48), whereas the lowest correlation was with PM2.5 (r=0.18). There was no consistent effect of traffic proximity on the correlations between community noise levels and traffic-related air pollutant concentrations. These results, consistent with previous studies, suggest that it is possible to assess potential adverse cardiovascular effects from long-term exposures to community noise and traffic-related air pollution in prospective epidemiologic studies. Crown Copyright (C) 2012 Published by Elsevier Inc. All rights reserved.