The research operationalizes sprawl through population density, housing unit density, roadway length density, and housing unit density measured against roadway density.
Because different aspects of traffic including density, roadway configuration, and average vehicle speed may affect emission rates, pollutant mix, and dispersion, we opted to create a suite of 25 traffic indicators (Table 1) capturing varying aspects of traffic.
NO2 showed significant spatial variability, predicted by population density and roadway length within 50 m of the home, modified by site characteristics (obstruction), and with higher concentrations during summer (R2 = 0.56).
Increases in eNO in those children with a higher density of roadways near their home would not be inconsistent with an allergic mechanism.
Thus, our final multivariate model (Table 5) includes covariates for traffic density, distance to roadways, roadway length and distance to the airport terminal.
Various GIS parameters (such as traffic and roadway density, population density, and land use) are used to predict the measured concentrations (Jerrett et al. 2007).
When we limited analysis to those children with both eNO and spirometry measures available, the association between eNO and roadway density, but not the association between spirometry and roadway density, remained statistically significant.
Roadway density was significantly associated with eNO, whereas LUR estimates of individual traffic-related pollutants were not, suggesting that local roadways may be a significant source of exposure not captured by the LUR, or that roadway density may better represent the complex mixture of traffic-related air pollution, which includes combustion products, asphalt, and rubber.
After controlling for age, sex, race, socioeconomic status, roadway density and air pollution levels, the scientists found that each increase of 10 decibels in noise level was associated with a 3.5 percent increase in cardiac-related hospitalization — for heart failure, heart rhythm disturbances, cerebrovascular events, ischemic heart disease or peripheral vascular disease.
Ventilatory lung function was not significantly associated with roadway density or air pollutant concentrations.
Finally, local roadway density may be a better indicator of traffic-related airway inflammation than LUR estimates of individual air pollutants.
