The global increase in air pollution has a number of consequences including damage to our environment and health. Bioindicators are living organisms which reveal certain qualities of our environment with their absence or presence. This is useful in identifying polluted areas in order to manage pollution levels. Parmelia sulcata is said to be a pollution-tolerant lichen and consequently a bioindicator. We wished to test P. sulcata's ability as a bioindicator, indicating poor air quality with its presence. We used randomized quadrat sampling of 80 trees over four municipalities on the Avalon Peninsula of Newfoundland, Canada with increasing human populations as a proxy for pollution. Results suggest that P. sulcata is not an ideal bioindicator of high pollution. It was absent or diseased in areas of highest pollution and present in areas of low-medium pollution levels. We recommend further studies evaluate P. sulcata's potential as a bioindicator of low-medium air pollution.