Air Pollution Bioindicators

Lichen

Lichen can be used as a biosignal to detect air pollution because it is sensitive to changes in the environment, including changes in air quality. When exposed to pollutants such as sulfur dioxide, nitrogen oxides, and heavy metals, lichens can experience changes in growth and reproductive patterns, as well as changes in their chemical composition. These changes can be used to indicate the presence and levels of pollutants in the air. Additionally, because lichen can grow on a wide range of surfaces, including rocks, trees, and buildings, it can be used to monitor air pollution in a variety of locations. This method of monitoring air pollution is known as "lichenometry."

To use lichen as a bioindicator, it is important to identify which lichen is in your area. The chart on the right shows the nine different types of lichen and what their presence entails.

Tar Spot Fungus

Tar spot fungus is a type of fungus that grows on sycamore leaves. It is sensitive to air pollution, particularly sulfur dioxide and nitrogen oxides, which are commonly found in urban areas. When these pollutants are present in high concentrations, they can cause the fungus to grow more abundantly and produce larger, darker spots on the leaves. By monitoring the presence and severity of tar spot on sycamore leaves in a specific area, scientists can use it as a biosignal to detect levels of air pollution in that area.

If you notice a high amount of tar spot fungus on sycamore trees near you, you may be in an area with high levels of air pollution.