The Sudeten Mountains are a region where the level of industrial air pollution is high due to brown coal combustion, but now the impact of pollution on the environment has greatly decreased. In this paper we attempted to determine how this fact affected the condition of silver fir trees. Our conclusions are based mainly on measurements of trunk diameter increments of 250 fir trees representing 42 populations of this species in different parts of the Sudeten. The main conclusion is that silver fir, at least to the age of 130 years, has the ability to endure unfavourable conditions and can substantially increase its growth rate in association with air quality improvement.