What Are Lichens Up Taking From the Air?

i was trying to balance the understanding that these lichens can't survive when there isn't so much air pollution. Yet, they are up taking pollution from from the air. We should be careful about what we take into our body and where it's coming from. There's nowhere to run from this glooino ther. So i'd be a d id watch where i collect by my herbal medicines, titat go.