Arbor Day, the holiday that encourages tree planting, is April 24th of this year. Trees offer lots of air quality benefits including absorbing carbon dioxide, releasing oxygen, and reducing particulate matter and ozone pollution. They can also address the “heat island” effect in urban areas. The “heat island” effect is observed where greenery is limited and buildings, roads, and other infrastructure absorb and reflect the sun’s energy creating “islands” of warmer temperatures compared to surrounding areas.1
Trees offer the benefit of absorption of carbon dioxide that is linked to climate change. They also provide oxygen – one tree can supply a day’s worth of oxygen for up to four people!2 The cooling effect of shade trees around buildings can help save money by reducing energy use by up to 25%.2 The shade also helps reduce the “heat island” effect in urban areas. Trees and vegetation are also able to cool the surrounding area through evapotranspiration, the process that trees and plants use to absorb water from their roots and evaporate it through their leaves. The air is cooled by using heat from the air to evaporate the water.3
Trees also filter air pollutants like particulate matter and ozone. Trees absorb gaseous pollutants like ozone through the leaf as they also intake carbon dioxide and other gases. Particulate matter can also be removed from the air by trees as certain leaves are able to trap the particulate matter that is either later removed by wind or removed by rain. 4
Some trees are better than others for removing air pollutants. Look for a future blog with information about which trees are best for removing pollutants. With all the air quality benefits offered by trees, consider planting a tree as an air quality effort to recognize Arbor Day! For more information about tree benefits, visit https://www.arborday.org or https://www.epa.gov/heatislands/benefits-trees-and-vegetation.
1 Environmental Protection Agency (EPA), https://www.epa.gov/heatislands/learn-about-heat-island-effects, Accessed 4.21.26
2 Arbor Day Foundation, https://www.arborday.org/value, Accessed 4.21.26
3 EPA, https://www.epa.gov/heatislands/benefits-trees-and-vegetation, Accessed 4.21.26
4 National Park Service (NPS), https://www.nps.gov/articles/000/uerla-trees-air-pollution.htm, Accessed 4.21.26