Under what conditions will scale lichens have advantages?

Scale lichens can develop in places where there is a high level of pollution. They need some substances that are found in exhaust gases, combustion products and other toxic substances. Therefore, the number of lichens can tell about the degree of cleanliness or air pollution in a particular area. The more of them on trees, poles and houses, the worse the air quality. But if somewhere there is a release of harmful substances, you should not expect a quick appearance of lichens. They grow very slowly. This may take several months.