Question

Why do lichens are rare or absent in cities​

Answer 1

Answer:

Lichens are used as the indicators of air pollution. These structures grow on tree bark and rocks. Air pollutants which are in the gaseous forms get dissolved in the rainwater, especially SO

2

(sulfur dioxide) can damage lichens, and check them from growing. In places where lichens are not growing, it indicates that the air is heavily polluted with sulfur dioxide and other pollutants. In cities, SO

2

is one of the most common air pollutants as it releases from the vehicles.