You might consider urban areas to be the epitome of cool, but that couldn’t be further from the truth. In fact, buildings, cars, pollution, and lack of soil, all contribute to an urban heat island effect, making cities considerably warmer than surrounding rural areas.

Luckily, there is a relatively simple way to spare city dwellers from the oppressive heat and extreme pollution in urban areas: planting more trees.

As it turns out, introducing more vegetation, like trees, into urban environments helps with everything from basic shade refuge to cleaner air to the reduction of energy costs.

One way that trees can help diminish both heat and pollution in urban areas is by simply providing shade. Strategically planting trees around non-shaded buildings help reduce the need for air conditioning. Lower energy costs also mean fewer pollutants and greenhouse gas emissions, so shade plays a role in maintaining healthy air quality in addition to keeping people cool.

According to the New York State Department of Environmental Conservation, trees also create cooler environments through the process of evapotranspiration. Evapotranspiration occurs when trees transpire water to cool themselves much like the way humans sweat to cool off. When the transpired water evaporates, the area surrounding the tree cools as well. The EPA notes that evapotranspiration and shade can help to lessen peak summer temperatures by 2 to 9 degrees.

Another, more commonly known, way that trees help their surrounding environment is by clearing the air of pollutants, which are often found in abundance in urban areas. Trees absorb harmful pollutants like nitrogen oxide, nitrogen dioxide, and sulfur dioxide, while simultaneously releasing the much-needed oxygen into the environment.

Lastly, trees, together with the surrounding soil, can also contribute to the well-being of a city by acting as a natural water filtration system. According to American Forests, rainwater is absorbed by the trees and is naturally filtered through the soil, meaning less water filtration is required in areas with trees than in areas without them. What’s more, planting trees in urban environments helps reduce water runoff created by storms.