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

Abstract

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 (Lday) with measured 5-min daytime A-weighted equivalent continuous noise levels (Leq,day,5min) at 103 selected roadside sites in the study region. On average, Lday was 6.2 (95% CI, 6.0–7.9) dB(A) higher than, but highly correlated (r=0.62; 95% CI, 0.48–0.72) with, Leq,day,5min. 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 ≤2.5μm (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.