Abstract. The aim of this study are (i) to determine the yearly and monsoonal variations of the criteria pollutants in Kuala Terengganu, (ii) identify the influences of the meteorological factors and other minor criteria pollutants that impose on the concentration of the most significant criteria pollutant using Principal Component Analysis (PCA). The hourly data for the criteria pollutants (PM10, CO, O3, NO2, and SO2) and meteorological factors (temperature, relative humidity, windspeed) for the duration of 10 years procured from the Department of Environment, Malaysia were analyzed. PM10 is the only pollutant that frequently recorded concentrations exceeding the MAAQG in the length of the year 2001 to 2010 and the criteria pollutants reported differ significantly between the monsoon seasons. PCA showed that sources contributing to the most significant criteria pollutant (PM10) are meteorological factor influences and industrial emissions.