Abstract
Background: Modern urban travel includes mixtures of transit options, which potentially impact individual pollution exposures and health. This study aims to investigate variations in traffic-related air pollution and noise levels experienced in traffic in Chengdu, China. Methods: Real-time PM2.5, black carbon (BC), and noise levels were measured for four transportation modes (car, bus, subway, and shared bike) on scripted routes in three types of neighborhoods (urban core, developing neighborhood, and suburb). Each mode of transportation in each neighborhood was sampled five times in summer and winter, respectively. After quality control, mixed effect models were built for the three pollutants separately. Results: Air pollutants had much higher concentrations in winter. Urban Core had the highest PM2.5 and BC concentrations across seasons compared to the other neighborhoods. The mixed effect model indicated that car commutes were associated with lower PM2.5 (−34.4 μg/m3; 95% CI: −47.5, −21.3), BC (−2016.4 ng/m3; 95% CI: −3383.8, −648.6), and noise (−9.3 dBA; 95% CI: −10.5, −8.0) levels compared with other modes; subway commutes had lower PM2.5 (−11.9 μg/m3; 95% CI: 47.5, −21.3), but higher BC (2349.6 ng/m3; 95% CI: 978.1, 3722.1) and noise (3.0 dBA; 95% CI: 1.7, 4.3) levels than the other three modes of transportation. Conclusion: Personal exposure to air pollution and noise vary by season, neighborhood, and transportation modes. Exposure models accounting for environmental, meteorological, and behavioral factors, and duration of mixed mode commuting may be useful for health studies of urban traffic microenvironments.
Highlights
A time-series plot for PM2.5 and black carbon (BC) raw data for day is shown in Figure 2 and shows the variations in different exposures that commuters experience as a single day is shown in Figure 2 and shows the variations in different exposures that commuters they transition between transportation modes within a multi-modal trip
Linear mixed models showed PM2.5 and BC levels in transportation were much higher in the winter time than the summer months, while noise levels were lower in the winter months
The current study showed that PM2.5 and BC concentrations were highly correlated (ρ = 0.84) in the Urban Core, which suggests that the source of the air particles in that area is likely traffic
Summary
Public, and shared options, physically active and non-active options, as well as combinations of mode types, such as walking, bicycling, and trips by car, bus, light rail, and train. Changes in urban mobility can potentially alter numerous population health determinants through physical activity levels, stress, access to resources, transportation-related costs, and time, as well as exposures to air pollution, noise, and other environmental stressors [1,2,3,4]. The impacts associated with mobility changes may differentially affect certain populations based on income and residential location [5,6,7,8]. Modern urban travel includes mixtures of transit options, which potentially impact individual pollution exposures and health. This study aims to investigate variations in traffic-related air pollution and noise levels experienced in traffic in Chengdu, China
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