Weather eye: Tracking air pollution wth lichens

Lichens are formed by a partnership between algae and fungi. They can be found growing on trees, pavements, gravestones and in other inhospitable places. These crusty organisms also tell us how dirty our air is.
Modern-day air pollution mostly comes from traffic, farming and industry, but the trouble is that we cannot always see it. Most lichens are like canaries in coalmines — they are very sensitive to dangerous gases and die. However, other lichens actually thrive on them.
A new study of lichens has been launched to map air pollution across the UK, and the public are being asked for help. Volunteers are needed to record the different lichens found growing on trees in their neighbourhood, and also count the number of tar spots on sycamore leaves. These are black blotches caused by a fungus that is also sensitive to air pollution. By gathering information from across the country, the Open Air Laboratories (Opal) project will map the impact of air pollution. “Are we seeing more of certain species in certain areas because the air is cleaner today? Or is it because the pollutants have changed?” asks Pat Wolseley, of the British Lichen Society, which is closely involved in the survey. “Everyone’s contribution to this survey is valuable; even a result of ‘no lichens’ still tells us something about the air quality in that area.”
Anyone can take part, and a free survey pack and recording chart can be obtained from airsurvey.org