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Pollution of the environment with ozone (O3) and organic pollutants has been steadily increasing over the past decades. Field studies on the synergistic effects of these pollutants are limited. We studied the effects of elevated O3 levels on pyrene degradation in soil, the bioaccumulation of pyrene, and the oxidative stress on wheat (Triticum aestivum L.) using a free-air concentration enrichment system. We grew wheat plants for two growing seasons in pots containing soil spiked with 0, 100 or 200 mg pyrene per kilogram of soil under ambient or elevated (+50%) O3 levels. Pyrene concentration in soil decreased over time and elevated O3 further. However, pyrene concentration in wheat shoots and seeds was higher under elevated O3 levels than under ambient conditions. Pyrene concentration in the soil was correlated to a higher activity of wheat superoxide dismutase, peroxidase, ascorbate peroxidase, and catalase, suggesting that pyrene caused an oxidative stress. Enzymes were higher under elevated O3 levels, except in soil with 200 mg added pyrene per kilogram of soil. Our results indicated that increasing O3 levels in the future may on one hand stimulate pyrene biodegradation, but on the other hand lead a higher accumulation in wheat. Thus, synergetic effects of these pollutants may increase their threat to food safety in the future.