Scientists at Portland, Oregon, are investigating evidence from multiple scientific fields which indicates that exposure to the natural environment can improve human health. The research was a reaction to the loss of 100 million trees in the eastern and mid-western United States. This deforestation gave them an opportunity to study the impact of a major change in the natural environment on human health.
The researchers used the analysis of 18 years of data from 1,296 counties in 15 states and found out areas infested by the emerald ash borer, a beetle that kills ash trees, had an additional 15,000 deaths from cardiovascular disease and 6,000 more deaths from lower respiratory disease, compared to uninfected areas. When emerald ash borer comes into a community, city streets lined with ash trees become bare. The emerald ash borer was first discovered near Detroit, Michigan, in 2002. The borer attacks all 22 species of North American ash and kills virtually all of the trees it infests.
Analysis of demographic data, human mortality rates and forest health data between 1990 and 2007 was done using information from counties with at least one case of emerald ash borer infestation. This suggests that there is an association between loss of trees and human mortality from cardiovascular and lower respiratory disease. The analysis did not prove a causal link, but a common pattern was found among the various demographic makeups considered in the study. The reason for the association is yet to be determined.
This information has intriguing implications. Similar work has shown that hospital patients recover faster when they have a more ‘natural’ environment, such as a view of natural landscape. The link between nature and human health may not be fully established, but this work adds to a body of work that does imply a relationship. Deforestation could therefore have implications beyond the more obvious environmental consequences – our very health may be affected.
