How Trees Reduce Air Pollution

Planting trees helps to improve air quality through 3 key impacts:

1. Altering the concentration of pollutants by reducing air temperatures
2. Reducing energy consumption in buildings (particularly for temperature control), which in turn reduces the consumption of energy from polluting sources 
3. Directly removing pollutants from the air

These impacts combine to create powerful, lasting effects for the the communities where trees are planted.

The Two main types of pollutants that trees remove from the atmosphere:

1. Gaseous air pollution: Tiny pores on the leaves of trees, called stomata, inhale air that contains toxic pollutants. Once absorbed, gases, including pollutants such as SO2, NO2, CO, and ozone, diffuse within the inner surfaces of the leaves, and are broken down.
2. Particulate matter:Trees remove some particulate matter from the air by temporarily “catching” it on their vegetative surfaces. When it rains, these particulates wash off of the tree and are carried into the soil or dissolve into stormwater. 

How Do Trees Produce Oxygen?

Trees produce oxygen through a process that you’ve probably heard of; photosynthesis. The tree’s leaves absorb carbon dioxide and water from the air, and use solar energy to convert it into chemical compounds, including sugars, that it can consume as food. Oxygen is a by-product of this process and is released by the tree. It has been estimated that, thanks to this process, one large tree can provide a day’s supply of oxygen for up to 4 people.

How much co2 do trees absorb?

In addition to absorbing airborne pollutants and releasing clean oxygen for us to breathe, trees absorb carbon dioxide from the atmosphere and use it to build their leaves, branches, trunks, roots, and the soil.

To determine the amount of carbon dioxide a tree can absorb, we combine average planting densities with a conservative estimate of carbon per hectare to estimate that the average tree absorbs an average of 10 kilograms, or 22 pounds, of carbon dioxide per year during the first 20 years of growth.