CITY TREES SAVE LIVES

Access to their benefits is a human right

Research amply establishes that urban tree canopy protects human health. 

In an example from 2020 specific to the Highline community, Public Health Seattle King County recommended (p 38) expanding green space and planting more trees near the airport to protect residents from aviation pollution. The report detailed research findings linking this pollution with shorter lifespans, widespread illness,  higher rates of premature births and low birthweights, and learning problems in children near SeaTac International Airport. 

Thousands of studies on tree benefits in urban areas conducted in the United States and throughout the world have been published in recent years.  A recent scientific review  examined 201 " published findings of quantified relationships between urban trees and human health" conducted prior to March, 2018.  A small sampling of the health benefits that the study identified include:

• Removing a variety of air pollutants,

• Reducing respiratory illnesses and deaths

• Cooling outdoor temperatures and, thus, reducing illness and death from heat

• Associated with reductions in crime rates

• Reducing sun exposure associated with skin cancer

• Associated with better birth outcomes,

• Associated with reduced stress, restored focus, and higher cognitive function

• Leading to improved immune function 

  Improved immune functioning was one of the strongest findings across multiple studies:

"Findings are consistently positive, indicating increased numbers of Natural Killer (NK) cells and NK activity, and reduced pro-inflammatory levels. It was found that increased NK activity can last more than seven days after a forest trip "  Urban Trees and Human Health: A Scoping Review, Kathleen L. Wolf et al, Int. J. Environ. Res. Public Health 2020, 17(12), 4371; https://doi.org/10.3390/ijerph17124371

(Urban Trees and Human Health: A Scoping Review, Kathleen L. Wolf et al, Int. J. Environ. Res. Public Health 2020, 17(12), 4371; https://doi.org/10.3390/ijerph17124371)

The scientific research on tree benefits continues. An important area of inquiry is which tree species provide the most protection for city dwellers. A study published in 2023 examined the relative ability of twenty different species of trees to shield reduce particle pollution from traffic and other urban sources:

“According to studies, tree species can successfully filter out atmospheric pollutants and retain particulate matter, which makes them a potent tool for enhancing urban environments and reducing the burden of air pollution. Each type of urban tree can accumulate different amounts of atmospheric PM2.5 on its leaves (Chen et al., 2017). According to Nowak et al., [10], trees clean the air by gathering particulate matter on their surfaces and absorbing gaseous pollutants through the stomata on their leaves. It has become commonly accepted in recent years that the removal of suspended particulate matter (SPM) from the air can be accomplished by using the right vegetation  

(Variation in the Ability of Various Tree Species to Capture Particulate Matter in Industrial and Urban Areas, Maisnam Sushima Devi, et al, International Journal of Environment and Climate Change, 13 (10), 37-46, 12/8/2023 )

The Port of Seattle, in its rush to strip forest from the residential communities near SeaTac Airport, is joining in a dangerous trend leading to loss of health and life across the country and significantly reducing both climate stability and the ability of people living in cities to withstand increasing levels of climate-change-related heat, dust, and drought:

“In the United States, urban tree canopy cover is estimated to be declining at a rate of roughly four million trees per year due to rapid urbanization and tree diseases and pests.”

(Urban Trees and Human Health: A Scoping Review, Kathleen L. Wolf et al, Int. J. Environ. Res. Public Health 2020, 17(12), 4371; https://doi.org/10.3390/ijerph17124371)