Correlations between PM exposures, traffic proximity, road traffic noise, and short-term environmental variables were assessed with Spearman's rank correlation coefficient.
In fact, our work is the first study that can make a direct comparison between the effects and hence indirectly of the toxicity related to the same amount (here for 1 μg/m) of PM-mass from traffic PM and from total PM that also contains several constituents which are not relevant for health such as e.g., sea salt [ 25].
We used generalized additive models, adjusting for short-term PM, meteorology, traffic proximity, and individual risk factors.
PM from traffic comprises road dust, vehicle particles, and exhaust particles, which have all been linked to adverse health outcomes [ 1].
Black carbon exposure showed the strongest associations, which suggests that carbon-containing PM from traffic or power plants were most important in causing vascular effects.
However, these are widely understood as reflecting primarily an effect of the complex mixture, including PM, from traffic combustion, rather than an effect of NO2 per se.
These variables are potential confounders because they are associated with BP outcomes and may be associated with residential location and therefore with PM and traffic exposures.
We used Pearson correlation analysis to explore the relationship between school CO ,PM concentrations, traffic counts, and distance to major roads using SPSS version 12.0.
Similarly to the findings of the Netherlands Cohort Study, in the German study conducted in North Rhine Westphalia the effects of PM and traffic appeared stronger for - or limited to - cardiopulmonary mortality (ICD-9 codes: 400-440 or 460-519) [ 9].
It is difficult to disentangle the effect of single air pollutants in epidemiologic designs because they are part of complex mixtures, but it seems likely that for cancer risk PM from traffic emissions is most important.
