Data from continuous measurements of SO2 NOx, suspended particulate matter (SPM) and meteorological parameters at seven sites around a highly industrialized region in the Aegean coast of Turkey, between July 15, 1991 to July 31, 1992 were used to evaluate spatial and temporal variations of air quality parameters. Low annual averages and insignificant differences between day and night concentrations were observed at stations far from sources. At stations close to sources, annual average concentrations were high and diurnal patterns were significant. Annual average SO2 and SPM concentrations in all stations used the 'Krigging' technique to assess the impact of industries on air quality in the surrounding airshed. Results have demonstrated that Turkish air quality standards for SO2 were exceeded in a circle with a radius of 4 km and which was centered on the petrochemical complex and refinery. Similarly, standards for SPM were exceeded in a circle with a radius of 1.2 km and which was centered on the ironwork plants. Both SO2 and SPM showed well defined diurnal variations, particularly in stations close to sources. The SO2 concentrations showed a maximum during day-time, while SPM concentrations peaked after midnight. Although annual average SO2 and SPM concentrations were highly variable depending on distances between stations and sources, background concentrations of the same pollutants, calculated by stripping episodes from data, did not change significantly from one station to another. Long range transport and resuspension of local soil were suggested as sources of background SO2 and SPM, respectively. The difference between observed and background concentrations of SO2 and SPM in each station was related to the impact of industries on air quality at that particular site.