Mass Urban

“Urban Forests = Cleaner, Cooler Air

Key Facts:

Poor air quality has led to an explosion of asthma cases and other health problems among vulnerable populations including children, the elderly, and low-income residents. Each year bad air causes two million deaths worldwide. Also, in the U.S., there have been 8,000 premature deaths from excessive heat over the past 25 years. Urban heat islands, which are caused, in part, by sunlight being absorbed by paved surfaces and roofs, lead to higher surface temperatures, up to 90 degrees. Atmospheric air temperatures are also higher: in the day by up to 6 degrees, and at night, by up to 22 degrees. Vulnerable populations also face greater risks of heat exhaustion. (Source: World Health Organization (WHO) and Heat Island Impacts, U.S. Environmental Protection Agency (E.P.A.) )

Increasing the tree canopy in cities is one way to fight both poor air quality and urban heat islands. Research shows significant short-term improvements in air quality in urban areas with 100 percent tree cover. There, trees can reduce hourly ozone by up to 15 percent, sulfur dioxide by 14 percent, and particulate matter by 13 percent. U.S. trees remove some 784,000 tons of pollution annually, providing $3.8 billion in value.”

Via: American Society of Landscape Architects