Temporal variation of NO, NO2, SO2, SPM (suspended particulate matter), and O-3 were measured at a high altitude station in the northwestern part of Turkey. The long- and short-term trends in the concentrations of measured parameters were investigated to understand sources contributing to the observed concentrations of these pollutants. Higher concentrations of O-3 during summer months were consistent with higher photochemical production with increased solar flux. Seasonal patterns observed in other parameters were consistent with their source strengths during different periods of the year. O-3 showed a peak at approximately 3 pm, together with SO2 and NO2. SPM, on the other hand, showed a different diurnal pattern with a maximum concentration occurring during night hours. The main sources of O-3, SO2, and NO2 on Mt. Uludag were found to be transported from the town of Bursa and from a nearby ski resort. The vehicular activities on the road which connects the town of Bursa to the ski resort are also an observable source of O-3 and its precursors, but not of SO2 and SPM. High concentrations of O-3 were observed during night hours. Unlike daytime peaks, these peaks were sporadic and did not correlate with the SO2 and NO2. These night-time O-3 concentrations were suspected to be due to injection from the stratosphere.