关键词：心脑血管疾病；死亡；人口
摘 要：Humans have intuitively understood the value of trees to their physical and mental health since the beginning of recorded time. A scientist with the Pacific Northwest Research Station wondered if such a link could be scientifically validated. His research team took advantage of an infestation of emerald ash borer, an invasive pest that kills ash trees, to conduct a study that gets closer to a definitive connection between the loss of trees and increased human mortality. Researchers analyzed data on demographics, tree loss from the emerald ash borer, and human mortality from lower respiratory disease and cardiovascular disease for 1990 through 2007. Results showed that the spread of the emerald ash borer across 15 states - first recorded in 2002 - was associated with an additional 15,000 deaths from cardiovascular disease and an additional 6,000 deaths from lower respiratory disease. Human mortality increased the longer emerald ash borer was present and killing trees. Deaths occurred at higher rates in wealthier counties, where more trees are typically found in urban areas. Although the study doesnt establish causation, it does suggest a link between trees and human health. This information can be applied to a range of fields including public health, urban forestry, and urban planning.