Forest decline in Japan has long been traced to air pollution and acid rain/fog, with ozone having high tree damaging records. This study investigated the eco-physiological changes brought to the evergreen conifer, Japanese red pine, by simultaneous fumigation of O₃ (O) and fluoranthene (F), a four ring polycyclic aromatic hydrocarbon, in a 90 d period. Seedlings were exposed singly or combined to 10 μM fluoranthene and O₃ (3 ppm h in the first 60 d, or 6 ppm h in the last 30 d period) in open top chambers. After 90 d, O+F treatment showed negative effects on the needle visual symptoms, net photosynthesis rate at near saturated irradiance, stomatal conductance,photochemical efficiency of PS II in the dark, total chlorophyll content and Chl a :Chl b ratios. F treatment showed similar results but in lesser magnitude compared with F+O treatment. O treatment alone showed no significant negative effect, probably due to its low concentration in the first two months; in most cases, its effects are same with the control. Mannitol(M) additions mitigated O+F & F negative effects. Fluoranthene deposited on needle surfaces of Japanese red pine presents greater ecological damages risk to the red pine at low O₃ concentration. The ubiquitous nature of fluoranthene combined with increasing trends of O₃ effects on vegetation should be a major global environmental interest.