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The spatial relationship between traffic-generated air pollution and noise in 2 US cities
Ryan W Allen1, Hugh Davies, Martin A Cohen
1Faculty of Health Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada. allenr@sfu.ca
Environmental Research
|February 6, 2009
Summary
Traffic-generated air pollution and noise share common sources, potentially causing confounding in health studies. Moderate correlations suggest considering regional pollution and wind direction to minimize this effect.
Area of Science:
- Environmental Health
- Epidemiology
- Cardiovascular Health
Background:
- Traffic-generated air pollution and noise are independently linked to cardiovascular disease.
- Shared traffic sources may lead to correlated exposures, posing a risk of confounding in epidemiological studies.
- Understanding the relationship between noise and air pollution is crucial for accurate health impact assessments.
Purpose of the Study:
- To investigate the correlation between traffic-generated air pollution (NO, NO2) and noise levels (L(eq)).
- To assess the impact of regional gradients, wind direction, and roadway proximity on these correlations.
- To determine if roadway proximity is a unique exposure surrogate for both air pollution and noise.
Main Methods:
- Measured nitrogen oxides (NO, NO2) and equivalent continuous sound pressure levels (L(eq)) at multiple locations across 9 US communities.
- Collected ultrafine particle (UFP) counts at a subset of sites.
- Analyzed correlations between pollution and noise metrics, considering roadway proximity, regional gradients, and wind direction.
Main Results:
- Noise (L(eq)) measurements were reliable and representative of long-term levels.
- Roadway proximity metrics effectively characterized noise levels, comparable to NO and NO2.
- Moderate correlations (0.20-0.60) were observed between noise and NO, increasing after accounting for regional gradients and especially when downwind of roads.
Conclusions:
- Roadway proximity is not a unique surrogate for both air pollution and noise exposure.
- Moderate correlations between traffic air pollution and noise indicate potential confounding in epidemiological studies.
- Epidemiological studies should consider regional pollution gradients and wind direction to mitigate confounding.
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