Traffic noise and particulate matter exposure; how can we distinguish between them in effect studies?

Abstract

Evaluating the health effects of traffic related air pollution at the one hand and noise at the other suffers from the uncertainties resulting from the co-exposure to noise and air pollution. In air pollution research, it has recently been observed that a large fraction of the diurnal exposure of traffic related components of air pollution such as black carbon (BC) is inhaled while in-traffic. Exposure at home or at work contributes only between 40% and 80% of the diurnal exposure, depending on the time-activity pattern, the travelled routes and the modal choice. The in-traffic exposure to BC is strongly affected by local traffic conditions (road type, traffic intensity, congestion, speed) and factors affecting dispersion (street canyons, microenvironment, meteorological conditions). To investigate combined exposure, a personal BC exposure measurement database with GPS registration is used. A strong relationship between noise levels extracted from noise maps and the measured BC level was observed for both indoor and in-car activities. A model for BC exposure based on LDEN noise levels and meteorological conditions could be established for different microenvironments allowing predicting the exposure to BC based on noise maps. Epidemiological evaluations based on stratification of the in-traffic contribution of personal BC exposure can be used to distinguish between the health effects of noise and air pollution. The in-traffic contribution of aggregated personal BC exposure can be estimated by evaluating the time-activity pattern on noise maps.