Field Notes from an Urban Forester – #2 Urban Forests and Human Health

  • Studies in urban woodlands have found effects of improved immune system response, lowered stress indicators, reduced depression and lower glucose levels in diabetics.
  • Increasing tree density, and resulting reduction in air pollution, has been shown to lower the prevalence of asthma attacks.
  • Exposure to air pollution has been positively correlated with negative birth outcomes such as preeclampsia, preterm birth and heart defects in newborns. Urban forests have been shown to effectively remove 5 of the 6 criteria air pollutants regulated by the U.S. EPA.
  • Bronchitis rates and hospital admissions are highly correlated with air pollution, in particular PM 10. Urban forests have been shown to effectively remove PM 10 from the air.
  • Increases in air pollutants such as sulfur dioxide (SO2) can result in increased respiratory-related hospital admissions. Urban forests have been shown to effectively remove SO2 from the air.
  • Hospital admissions for heat-related illnesses such as dehydration, heat stroke and heat exhaustion increase significantly during heat wave events. These heat-related illnesses are often more pronounced in urban areas due to a lack of shade and cooling effects of vegetation from evapotranspiration.
  • Green parks and restorative settings are becoming standard features at hospitals and recovery facilities. The experience of nature promotes more rapid and thorough healing.

For further information please visit the University of Washington’s ‘Green Cities-Good Health’ website:    http://depts.washington.edu/hhwb/