So far in this book, we have presented the evidence for agriculture as a polluter of our environment. Yet agriculture also suffers from pollution, in particular from pollutants in the air derived from industrial and urban activity, and from agriculture itself. Crops and livestock may be damaged by concentrated pollutants emitted by nearby industries, for example sulphur dioxide from power stations or fluorides from brick factories:. Equally, though, agricultural production is at risk from moderately raiised levels of pollutants in the ambient air of rural areas, as a result of long distance dispersal from industrial, urban or agricultural origins.