Cities should be planting more trees, but the reasons why may be more complicated than you think. As it turns out, trees provide so much more than aesthetics and a way for humans to connect with nature. More and more research is emerging about how the proper implementation of tree planting in urban areas and cities could help solve growing environmental issues.

adult and child use their hands to plant a tree in soil

We already know that nature can improve mental health. It can inspire positive engagement with community and provide the kind of groundedness one needs to live in the moment. A 2017 study published in the Journal of Positive Psychology examined the emotional effects of taking time to notice nature versus human-built objects by dividing participants into three different groups. The group instructed to pay more attention to nature had significantly higher levels of elevating experiences, a sense of connectedness and intent to help others. That means you don’t necessarily have to plan an epic week-long camping trip (though that sounds great!) to reap nature’s benefits. Something as simple as walking through a park on your morning commute or stopping to admire a tree at the bus stop can create positive effects.

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A report published by the Nature Conservatory in 2016 found that investing $100 million annually in tree planting in cities could provide cooler temperatures for 77 million people and cleaner air for 68 million people. That’s a pretty important statistic, considering that a “vast majority” of humanity will be living in cities, towns and other urban areas by the year 2050. When it comes to pollution, the bulk of cities are most greatly affected by particulate matter, AKA the consequence of burning fossil fuels from cars and factories. Fine particulate matter inhalation into the lungs alone causes an estimated 3.2 million deaths per year from complications such as stroke, heart disease and respiratory illness. According to the report, by the year 2050 this number could almost double if something isn’t done. The good news is, the leaves of trees act as an absorber of these pesky pollutants, and the matter itself can get caught or retained on the tree surfaces.

view of tall tree illuminated by sun rays from the ground

Fortunately, we already have some of the answers to these pressing problems. The Nature Conservatory studied 245 cities in 2016 to find that trees are already providing humans with benefits such as reductions in fine particulate matter and reduction in summer maximum temperatures, and that was just the trees that were already there. Significant tree cover in cities can also help reduce the need for air conditioning, reducing utility costs and lowering energy usage.

Tree planting, when combined with other strategies, appears to be a cost-effective, simple way to improve the environment and soak up air pollution, all while beautifying the neighborhood. In order to make this approach most effective, the types of trees planted must be considered as well. Trees with larger leaves provide more sufficient shade and are more productive in absorbing pollutants. Species that are less susceptible to drought may also be considered in areas where water is more scarce. Maintenance is another factor to consider, as it may not cost much to plant the trees in the first place, but watering, pruning and protecting against diseases all require added costs and labor for city trees.

person used shovel to pour soil into planted tree

Trees aren’t the only air purifiers in the natural world. Certain types of moss can produce oxygen while binding environmental toxins such as particulate matter and nitrogen oxides, which at high levels can damage the ozone layer and human lungs. Berlin-based company Green City Solutions is creating irrigated city park benches made of condensed moss. The benches have the ability to absorb air pollutants and use installed fans to create large area-covering air flow. In 2018, Goodyear released a tire design made with living moss that helps improve air quality as you drive.


Air pollution was the theme for the 2019 World Environmental Day, held on June 5. Thousands of people took to social media to show their support with the hashtag  #BeatAirPollution and pledging to make lifestyle choices to support the fight for cleaner air. Officials from different countries made big announcements involving environmental issues such as Kenyan President Uhuru Kenyatta, revealing a ban on single-use plastics in national parks. Other politicians who joined were Canadian Prime Minister Justin Trudeau’s who pledged to phase out coal-use in Canada by 2030 and Chilean President Sebastian Piñera’s plan for Chile to go carbon neutral by the year 2050. UN Secretary-General António Guterres was quoted saying, “My message to governments is clear: tax pollution; end fossil fuel subsidies; and stop building new coal plants. People everywhere are demanding action. On World Environment Day, let us heed their call.”

Via UN Environment

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