Lichens are considered to be excellent indicator species for pollution. Areas with healthy lichen populations are lower in air pollution and water pollution. Lichens are very sensitive to which chemical in the air?

Lichens are indeed excellent indicator species for pollution levels, particularly air pollution. They are very sensitive to sulfur dioxide (SO2) in the air. Sulfur dioxide is a common pollutant emitted from industrial processes, burning fossil fuels (such as coal and oil), and volcanic eruptions. High concentrations of sulfur dioxide can harm lichen populations, leading to their decline or absence in polluted areas. Therefore, the presence and health of lichen populations can provide valuable information about air quality and pollution levels in a given environment.