The etiopathogenesis of potentially malignant oral disorders (PMOD) has not been fully understood yet. Recent results suggest that oxidative stress may be involved in the etiology of PMOD. Production of oxidants seems to be the major biological effect responsible for tissue injury and inflammatory response to air pollution. The aim of this study was to compare the oxidative stress markers and antioxidant potential in saliva of PMOD subjects and healthy controls in periods of high and low air pollution. Among enrolled 40 participants, there were 20 PMOD patients and 20 healthy volunteers. The exposure to air pollution was assessed by exhaled CO (eCO). Four oxidative status parameters: 8-hydroxy-2'-deoxyguanosine (8-OHdG), malondialdehyde (MDA), reduced glutathione (GSH) and total antioxidant capacity (TAC) were measured in saliva. Measurements were carried out in June (low air pollution) and November (increased air pollution). In both groups, significantly higher concentrations of 8-OHdG (P < 0.001 for PMOD patients and P = 0.001 for healthy controls), MDA (P = 0.002 and P = 0.012 respectively) and eCO (P < 0.001 and P < 0.001 respectively) were observed in periods of high air pollution. The concentration of TAC did not change between visits. The concentration of salivary GSH (P < 0.001 and P < 0.001 for both groups) decreased when compared between consecutive visits. We conclude that exhaled carbon monoxide (reflecting exposure to air pollution) correlated with the oxidative stress markers in patients with PMOD and healthy controls.