What explains the lack of lichens near major motorways and industrial sites?

Lichens obtain mineral substances mainly from dust in the air and from drops of rainwater. Therefore, they have a high sensitivity to the purity of the air, since together with minerals they absorb harmful toxic substances. This is due to the lack of organs in lichens to extract fluid and absorb it with the entire thallus (lichen body). The main reason for the death of many lichens is the high content of sulfur dioxide in the air.