Local meteorological conditions exert a strong influence over day-to-day variations in air pollutant concent-rations. Therefore, the meteorological fluctuations have to be removed in order for air quality planners andmanagers to examine underlying emissions-related trends and make better air quality management decisions forfuture. In this study, the meteorologically adjusted PM10 trends in Seoul are investigated over the period 1999~2006 using Kolmogorov-Zurbenco (KZ) filter. The result indicated that meteorological variability accounts forabout 25% of PM10 variability. Both the meteorologically adjusted and unadjusted long-term daily PM10 con-centrations had a significant downward trends and the difference between the meteorologically adjusted andunadjusted was small. So it was assumed that in long-term daily PM10 changes, localized changes in emissions ismore important than the changes caused by meteorological conditions.