A feasibility study was undertaken in Alabama near a point source of sulphur dioxide, emissions to determine the best film-filter-scale combination of aerial photography to evaluate SO2 injury to forest vegetation. Normal color film, exposed through a didymium filter, at very large scales (1:800 and 1:1,584) proved to be the most accurate sensor. Color infrared film was almost as good. Interpreter differences were least at large scale and on color film. Ground variables which were best correlated with photo interpretation were: crown color, needle color, Munsell hue, percent of current needles with tip dieback and the length of the tip dieback. A combination of photo and ground plots appears to be the most efficient design for measuring these effects--especially if done over large areas.