ABSTRACT
Motor vehicles are the primary source of acid-forming pollutants such as nitrogen oxides, and are responsible for growing levels of ground-level ozone, a substance which hastens the formation of acid rain. Acid rain is acknowledged to be a widespread problem in the industrialized nations—with damaged trees, corroded buildings and dead lakes highlighting the urgency of remedial measures. Some researchers believe that acid rain increases the acidity of the forest soil, causing essential nutrients to be washed away whilst leaving roots of trees exposed to toxic aluminium. In the Black Forest of Germany a direct link between transport and acid rain damage was made by the forestry authorities in the mid 1980s. Nitrogen compounds are seriously stressing Europe’s forests. The estimated total nitrogen inputs to forests in central Europe and southern areas of the Nordic countries usually exceed the calculated tolerance limits of nature several times over.
