Four-year-old potted Norway spruce (Picea abies (L.) Karst.) grafts established with scion material from three mature trees, were exposed to either long-term fumigation with SO2, with and without water stress, or long-term ozone fumigation. The electrical conductivity of the needle diffusate was measured after the needles had been washed with chloroform and then leached in distilled water. Although none of the treatments caused visible symptoms of injury, SO2 fumigation and water stress both caused an increase in diffusate conductivity, but the effects were not synergistic. Ozone fumigation lowered both conductivity and nutrient ion concentration in the leachate.