Pollutants from Vehicle Exhaust Near Highways

Abstract

Introduction 87 Background 88 Motor Vehicle Pollution 88 Air Pollutant Gradients Near Highways 89 Cardiovascular Health And Traffic-Related Pollution 93 Asthma And Highway Exposures 97 Pediatric Lung Function And Traffic-Related Air Pollution 98 Cancer And Near-Highway Exposures 99 Policy And Research Recommendations 100 Conclusion 100 Keywords 101 References 101 Credits 106INTRODUCTIONThere is growing evidence of a distinct set of freshly emitted air pollutants downwind from major highways, motorways, and freeways that include elevated levels of ultrafine particulates (UFP), black carbon (BC), oxides of nitrogen (NOx), and carbon monoxide (CO). People living or otherwise spending substantial time within about 200 m of highways are exposed to these pollutants more so than persons living at a greater distance, even compared to living on busy urban streets. Evidence of the health hazards of these pollutants arises from studies that assess proximity to highways, actual exposure to the pollutants, or both. Taken as a whole, the health studies show elevated risk for development of asthma and reduced lung function in children who live near major highways. Studies of particulate matter (PM) that show associations with cardiac and pulmonary mortality also appear to indicate increasing risk as smaller geographic areas are studied, suggesting localized sources that likely include major highways. Although less work has tested the association between lung cancerand highways, the existing studies suggest an association as well. While the evidence is substantial for a link between near-highway exposures and adverse health outcomes, considerable work remains to understand the exact nature and magnitude of the risks.