The objective of this study was to investigate the variations and correlations of the air pollutants during Covid-19 pandemic lock-down period for an industrialized city of Turkey. With this aim, air quality data measured at four different stations in the period March–June 2020 were used. Results of the study demonstrated that lock-down period caused significant decreases in pollution levels in urban, industrialized, and rural sites. In the city center (Station 2), reduction determined for PM10 and NOx levels were 32.95% and 58.26%, respectively whereas in the industrialized site (Station 3) decrease ratios of these pollutants were 17.11% and 47.87%, respectively. Obtained reduction ratios may indicate that industrial and traffic activities have more significant contributions to NOx emissions in the region. A strong positive correlation between CO and NOx (r = 0.87) may also be evidence for traffic-related pollution in the city center while positively correlated NOx and SO2 levels indicate the importance of point sources for Stations 1 and 3. Coherent with the literature, O3 emissions showed increasing tendency both in moderately industrialized (Station 1) and rural sites (Station 4). When average concentrations of the pollutants were compared for May 2019 and May 2020 periods, the most significant variation was noted for the industrialized region with 50.07% reduction in NOx values.