This study considers the characteristics of nitrogen dioxide (NO₂), ozone (O₃) and sulfur dioxide (SO₂) in three cities of Daegu-Gyeongbuk Area (Daegu, Pohang, and Gumi), which have different city or industrial characteristics, over a time period of 2 years. The diurnal, weekly, monthly and seasonal concentration variations of criteria air pollutants were attributed to compounds or city types. However, the seasonal variations of O₃ concentrations were dependent on compounds, but not on city types. Lower O₃ concentrations were observed in July when comparing with other summer months. For SO₂ and NO₂, the concentrations were higher in Daegu when compared to Pohang and Gumi, while the concentrations of O₃ were higher in Pohang and Gumi. SO₂ exhibited higher levels in the morning hours, while O₃ and NO₂ exhibited higher levels in the afternoon hours for all cities. For O₃, the concentrations observed during Sunday were higher than those of other week or weekend days. Furthermore, the monthly and seasonal concentration variations of air pollutants depended on compounds or city types. It is noteworthy that the current monthly and seasonal variations were consistent with several previous studies.