Additionally, the two sites evaluated might not be representative of other locations, and it is unclear how the models for those two sites represent exposure of nearby populations to air pollution. However, they noted that there was not enough variation in some of the new parameters to include them in the statistical models. The Committee concluded that strengths of the study were the detailed characterization of the study areas and incorporation of the perspectives from transportation and other fields into the study of near-road air quality, the use of novel traffic indices with distance-weighted traffic activity, and the use of dispersion model parameters as contributors to statistical models of air pollution. In its independent review of the study, the HEI Review Committee concurred with the investigators that this study demonstrated that detailed characterization can sometimes be useful for developing statistical models that estimate near-road air pollutant concentrations. Inclusion of dispersion model parameters improved the statistical models of the pollutants most strongly related to traffic at the freeway site but were less useful for predicting fine particle concentration at the freeway site or any of the pollutants measured at the urban intersection site. Some other new potential parameters explored by the investigators (e.g., built environment and elevation) were not included in the final models because they did not contribute to the model R 2, most likely because the study areas were very small. Local and real-time weather and traffic were useful parameters in statistical models of some of the pollutants, especially near the freeway. At the freeway site, the models had moderate performance for black carbon, moderate to good for ultrafine particles, nitric oxide, and nitrogen oxides, and good for fine particles at the urban intersection site, the models had poor performance for fine particles, moderate for ultrafine particles, and good for ozone. Statistical model performance varied by both pollutant and site. Air pollutant concentrations were higher near the freeway than the urban intersection and decreased with increasing distance from traffic at both sites. They incorporated key concepts from various fields related to roads and air pollution, including transportation, mobile source emissions, traffic operations, and meteorology.įrey and colleagues compiled a comprehensive database of traffic-related and land use variables from measurement campaigns in two study locations (a freeway and a busy urban intersection) in North Carolina. One question they posed was whether more detailed measurements of factors affecting near-road air pollutant levels can help with the development of models of concentrations of primary and secondary air pollutants within hundreds of meters of roads, and which of those measurements most improved the air quality model performance at different locations and times. Christopher Frey from North Carolina State University and his team proposed a study to explore how traffic activity metrics, land use parameters, and transport of pollutants influence near-road air pollutant concentrations. Developing accurate models of traffic-related air pollution for use in exposure assessment for epidemiological studies relies on understanding traffic activity and air flow at small spatial scales within cities.ĭr. ![]() However, exposure assessment is challenging because traffic-related air pollution is a complex mixture of many particulate and gaseous pollutants and is highly variable across locations and time. For more information go to emissions are an important source of urban air pollution, and exposure to traffic-related air pollution has been associated with various adverse health effects. Proposition 65 Warning for California Residents: This product can expose you to chemicals including Benzene, which is known to the State of California to cause cancer and birth defects or other reproductive harm. ![]() (8.4 cm x 17.8 cm x 4.4 cm)įour AA-size batteries or optional AC adapter TSI 5725 Velocicalc Rotating Vane AnemometerĪctual range is a function of velocity and duct areaģ.3 in.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |