Critical Load/Level Values

10 µg SO2 m-3 annual mean.

Status
UNECE, 2004
Habitat/Ecosystem Type
Cyanobacterial lichens
Description

SO2 dissolves in water to produce acidic ions which are readily absorbed through the lichen thalli disrupting photosynthesis. SO2 has also been shown to inhibit the activity of nitrogenase, which is used by cyanobacterial photobionts to fix atmospheric nitrogen.

Reference: Gries, C. (2008). Lichen sensitivity to air pollution, Chapter 13 in Nash, TH, III (ed.) Lichen Biology (2nd. ed.), Cambridge University Press, Cambridge.

Reliability
quite reliable i.e. the results of some studies are comparable