Large trees make us healthier

Aren’t Urban Trees A Public Health Issue?

Large trees make us healthier

Sometimes, in order to bring new understanding to an issue and cut through the meaningful-but-sometimes-numbing-data, you need to reframe it. There are so many ways that big trees enhance life for people and other living things: air quality, safety, water quality, lower temperatures. These cross environmental, development, and design boundaries. All are fundamentally public health issues, and maybe we should be talking about them more using more public health language. 

Crime reduction, for example. We know (read more here, here, and here) that trees have a strong negative association with all types of crime. To quote the authors of the 2001 study, “Environment and Crime in the Inner City: Does Vegetation Reduce Crime,” by Frances E. Kuo and William Sullivan, “The greener a building’s surroundings are, the fewer total crimes.”

The effect of trees on air quality (which is closely linked to incidents of asthma) is equally compelling. According to a 2002 study by Dr. David Nowak, with the USDA Forest Service,  large, healthy trees greater than 77cm (30”) in diameter remove 70 times more air pollution annually than small, healthy trees less than 8cm (3”) in diameter.

Small Tree versus Large Tree - benefits

Soil and its microbes, in combination with trees, are also incredible mechanisms for improving water quality. As we’ve written about before, soil holds or filters some pollutants, while others are taken up or transformed by plants or microbes.

Trees and other plants also help lower temperatures, particularly in paved areas like cities, where the urban heat island effect can magnify rising temperatures by as much as 8 or 10 degrees.

These are not just “environment” issues. These are also people issues, with very real socioeconomic implications.

People tend to become passionate about particular issues when they become personal (remember “the personal is the political”?).  If you knew that you could live a safer, healthier existence by doing something as simple as designing streets, plazas, and parking lots that could support robust urban forests, wouldn’t that be one of the simplest decisions you could make?

Image: Willamor Media

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