Research results show that the mortality rate of residents is lower in areas where more street trees are planted

In recent years, it has become known that the ``surrounding environment of the place where you live'' affects

life expectancy and health , and it has been reported that living in a place with a lot of nature has various benefits . A new study led by the U.S. Department of Agriculture Forestry Service and the Barcelona Institute for Global Health (ISGlobal) showed that ``inhabitant mortality is lower in areas with more planted street trees.''

The association between tree planting and mortality: A natural experiment and cost-benefit analysis - ScienceDirect

Planting Trees Can Save Lives, Study Shows - News - ISGLOBAL

People in Portland Planted Trees. Decades Later, a Stunning Pattern Emerged : ScienceAlert

While a variety of studies show the health benefits of being in contact with nature, most studies use satellite imagery to estimate local vegetation indices, says ISGlobal researcher Payam Dadvand. Point is the problem. Since it is not possible to distinguish various vegetation from satellite images, it is difficult to reflect research results in concrete policies.

Therefore, the research team of Dadvand and others focused on the tree planting activities that the non-profit organization Friends of Trees has been doing in Portland, Oregon for 30 years. Friends of Trees planted 49,246 street trees between 1990 and 2019 and kept records of the locations and times when trees were planted, so the research team used this data for analysis. I was.

The research team examined the number of street trees planted over the past 5, 10, and 15 years in specific regions or census tracts used in the US Census. In addition, data from the Oregon Department of Health was used to correlate and analyze mortality from non-accidental causes, such as cardiovascular disease, respiratory disease, and accidents and incidents, in each district.

Studies have shown that areas with more trees have lower resident mortality rates. The correlation between street trees and mortality was significant in mortality from cardiovascular disease and non-incidental causes, especially in men aged 65 years and older. Specifically, the study found that planting an average of 11.7 trees per district per year would reduce the number of deaths from cardiovascular disease by 5 and by 15.6 from non-accidental causes per year. The team is estimating.

Furthermore, it was found that the effect of reducing the mortality rate increased with the growth of trees. The mortality rate reduction associated with street trees planted in the last 1-5 years was 15% per 11.7 trees, but reached 30% for street trees planted in the last 11-15 years. The results suggest that older trees are associated with significantly lower mortality and that preservation of mature trees may have public health benefits. The age of the tree when it was planted by Friends of Trees was 4 to 8 years old.

The researchers estimated that planting one tree in each of Portland's 140 census tracts would reduce the number of non-accidental deaths by 1.33 per year. The US Environmental Protection Agency estimates the value of statistical adult life at $ 10.7 million (about 1.4 billion yen), and the cost of planting and maintaining 140 street trees is $ 2716 to $ 13,720 (about 360,000 yen to about 1.8 million yen), the research team wrote that even if one street tree was planted in each district, the cost would be balanced.

Geoffrey H. Donovan of the U.S. Department of Agriculture Forestry Service, the first author of the paper, said, ``The effect was confirmed in both areas with lush greenery and those without. It was suggested that it would bring benefits,' commented. 'Our findings provide an important evidence base for specific interventions such as planting trees to extend the lifespan of urban dwellers,' said Dadvand.

in Science, Posted by log1h_ik