The associations between traffic-related air pollution and noise with blood pressure in children: Results from the GINIplus and LISAplus studies

Although traffic emits both air pollution and noise, studies jointly examining the effects of both of these exposures on blood pressure (BP) in children are scarce. We investigated associations between land-use regression modeled long-term traffic-related air pollution and BP in 2368 children aged 10 years from Germany (1454 from Munich and 914 from Wesel). We also studied this association with adjustment of long-term noise exposure (defined as day-evening-night noise indicator "Lden" and night noise indicator "Lnight") in a subgroup of 605 children from Munich inner city. In the overall analysis including 2368 children, NO₂, PM_2.5 mass (particles with aerodynamic diameters below 2.5μm), PM₁₀ mass (particles with aerodynamic diameters below 10μm) and PM_2.5 absorbance were not associated with BP. When restricting the analysis to the subgroup of children with noise information (N=605), a significant association between NO₂ and diastolic BP was observed (-0.88 (95% confidence interval: -1.67, -0.08)). However, upon adjusting the models for noise exposure, only noise remained independently and significantly positively associated with diastolic BP. Diastolic BP increased by 0.50 (-0.03, 1.02), 0.59 (0.05, 1.13), 0.55 (0.03, 1.07), and 0.58 (0.05, 1.11)mmHg for every five decibel increase in Lden and by 0.59 (-0.05, 1.22), 0.69 (0.04, 1.33), 0.64 (0.02, 1.27), and 0.68 (0.05, 1.32)mmHg for every five decibel increase in Lnight, in different models of NO₂, PM_2.5 mass, PM₁₀ mass and PM_2.5 absorbance as the main exposure, respectively. In conclusion, air pollution was not consistently associated with BP with adjustment for noise, noise was independently and positively associated with BP in children.