Effects of Greenness and Noise Exposure on Health

Abstract

Environmental epidemiology has begun to investigate attributes of the physical environment in which people live, work and play daily that are associated with health. Features of the environment bear on risk factors for chronic diseases prevalent in the U.S. and elsewhere. For example, physical inactivity, overweight and obesity all profoundly influence downstream health, and the physical environment may provide opportunities to intervene for desirable outcomes. Interventions in the physical environment can complement education and behavior change activities already being pursued, such as incentives to exercise and education on healthy diets. Among these attributes of the physical environment important for health, researchers have begun to study the effects of exposure to nature. Growing evidence seems to suggest that nature (often operationalized as exposure to vegetation, or vegetative density) may positively influence many health endpoints. Another recent exposure of interest is neighborhood noise level, which has been investigated not solely as a cause of annoyance or auditory effects but as a potential contributor to cardiovascular disease. Both of these relatively new research areas provide opportunities for environmental health interventions. The evidence base, however, would benefit from prospective studies in large cohorts. The objective of my doctoral research was to examine the association between these exposures and prevalent risk factors and health outcomes prospectively. Using data from the long-running cohort of professional women, the Nurses’ Health Study, I examined the relationship between surrounding greenness and depression, finding that those who lived in the greenest areas were statistically significantly less likely to develop depression over the course of follow-up. I also considered the relationship between surrounding greenness and incident overweight and obesity in the Nurses’ Health Study II, finding little evidence for an association. Finally, I examined the association between nighttime residential noise level and incident hypertension in the Nurses’ Health Study II. I found that greater noise levels were statistically significantly associated with increased risk for incident hypertension. These studies contribute to our understanding of how attributes of the physical environment may influence health, incorporating information from large prospective cohort studies in the U.S.