Selected aspects of the urban environment in relation to human health : An analysis of residential road traffic noise and surrounding greenness in the Heinz Nixdorf Recall study
The main aim of this thesis was to analyze residential road traffic noise and surrounding greenness in relation to different aspects of human health. The thesis comprises two publications, which used data from the German Heinz Nixdorf Recall study including 4,814 middle aged and older men and women living in the Ruhr metropolitan region in Germany. For the first publication, a prospective approach was used to study the effect of residential road traffic noise with depressive symptoms after five years of follow-up in participants that were free from depressive symptoms at baseline. We found that high depressive symptoms occurred about 30% more frequently in study participants exposed to mean annual road traffic noise levels >55 dB(A) compared with ≤55 dB(A), taking relevant potential confounding factors into account. The second publication comprises a cross-sectional analysis of the association between residential surrounding greenness measured by Normalized Difference Vegetation Index (NDVI) and self-rated health. Further, relationships of greenness and self-rated health with neighborhood satisfaction, perceived safety, social satisfaction and neighborhood social capital were analyzed. We found that a 0.1-increase in residential NDVI reduced the odds of poor self-rated health by approximately 10%, considering NDVI both in the 100-m and the 1000-m radius around home and adjusting for potential confounders. Greenness was also positively associated with neighborhood satisfaction and neighborhood social capital which in turn were also associated with better self-rated health. Social satisfaction and perceived safety were associated with better self-rated health, but not with residential surrounding greenness measured by NDVI. The results of this thesis are in line with the presumed health impacts of residential road traffic noise and surrounding greenness and provide support for results that have been reported in previous research. This stresses the importance of the environmental factors traffic noise and surrounding greenness for public health and urban planning. Future studies on these topics should aim to additionally incorporate qualitative measures of environmental exposures.