Sulphur dioxide fumes have been affecting the forests around Wawa, Ontario, which have been under surveillance for a. number of years and which were recently covered by ultra-small-scale (1:160,000) air photography for damage-assessment purposes. Selected as a Canadian Forestry Service ERTS-1 test site, the area was imaged on four successive ERTS-1 passes during the summer of 1973. Interpretation supported by electronic color enhancement was used to delineate, on ERTS imagery, three damage zones: total-kill, heavy-kill and medium-damage zones. The zones delineated are similar to the results of aerial sketch mapping and airphoto interpretation. Band 5 provided the greatest detail for assessing the damage to the forests, followed by bands 4, 6 and 7. Comparison with winter ERTS images showed that even though the total kill could be separated from heavy-kill damage zoned, total kill could not be consistently separated from clear-cut logging, burned areas, frozen lakes and bogs.