Women in the U.S. who live in homes surrounded by more vegetation appear to have significantly lower mortality rates than those who live in areas with less vegetation, according to a new study.
The finding is published in the journal Environmental Health Perspectives. Harvard T.H. Chan School of Public Health and Brigham and Women’s Hospital led the research.
Previous studies have suggested that exposure to vegetation was related to lower death rates, but those studies were limited in scope, and some had contradictory findings.
The new study is the first to take a nationwide look at the link between greenness and mortality rates over a period of several years.
The study incorporated data on 108,630 women enrolled in the Nurses’ Health Study across the United States in 2000-2008.
The researchers compared the participants’ rate of mortality within the study period with the level of vegetation surrounding their homes, which was calculated using satellite imagery from different seasons and from different years.
The researchers controlled other mortality risk factors, such as age, socioeconomic status, race and ethnicity, and smoking behaviors.
When they looked at specific causes of death among the study participants, they found that associations between higher amounts of greenness and lower mortality rates were strongest for respiratory-disease and cancer mortality.
Women living in areas with the most vegetation had a 34% lower rate of respiratory disease-related mortality and a 13% lower rate of cancer mortality compared with those with the least vegetation around their homes.
These more specific findings were consistent with some of the proposed benefits of greener areas, including that they may buffer air pollution and noise exposures and provide opportunities for physical activity.
The researchers suggest several mechanisms that might be at play in the link between greenness and mortality rates.
Improved mental health, measured through lower levels of depression, was estimated to explain nearly 30% of the benefit from living around greater vegetation.
Increased opportunities for social engagement, higher physical activity, and lower exposure to air pollution may also play an important role.
Citation: Peter James, et al. (2016). Exposure to Greenness and Mortality in a Nationwide Prospective Cohort Study of Women. Environmental Health Perspectives, published online. DOI: 101289/ehp.1510363.
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