A report on the likely effects of current levels of air pollution on forest growth in North America concluded that, since nitrogen is a necessary nutrient for optimal plant growth, the nitrogen deposited on forest soil as a result of air pollution probably benefits eastern forests  However, European soil scientists have found that in forests saturated with sulfate and nitrate, trees begin to die when the nitrogen deposited exceeds the amount of nitrogen absorbed by the forest system
Since this finding is likely to apply to forests everywhere, large areas of eastern forests of North America are, undoubtedly, already being affected adversely
Contrary to the report cited, the nitrogen pollution now in the air is more likely to cause trees to die in eastern forests than to benefit them.