Figure 3

Chronic ambient O3 exposure reduced the leaf injury index percentage (LII%). Seedlings cultured in charcoal-filtered air (CF, n = 24) and indoor ambient air (NF, n = 24) for 3 weeks were exposed to 150 ppb O3 for 8 hours in a controlled chamber. The LII% was measured 2 days after exposure. The extent of foliar injury in NF seedlings was significantly decreased compared to that in CF seedlings (p < 0.01, t-test).