The major goals of this work are executing quality assurance checkups on aerosol monitoring from supersite and validating monitoring data. To achieve this goal, the standard operating procedures for performance audit are established and regular and irregular audits are performed. At the end of October, this work had accomplished seven monthly regular checkups, two irregular checkups, half-of-the-year calibration on instruments, and five monthly meetings for performance coordination. From January to October 2003, data availability for instruments in supersite is as follows. 98% for PM10, 98% for PM2.5, 87% for PM2.5 carbon, 77% for PM2.5 nitrate, 66% for PM2.5 sulfate, 75% for PM2.5 PAH, 99% for PM2.5 black carbon, 77% for aerosol light-scattering coefficient, 95% for aerosol size distribution from submicron to micron size, 90% for aerosol size distribution from nanometer to submicron size. The downtime for PM2.5 sulfate was 3 months and PM2.5 nitrate measurement had occasionally low values. This year, more than 30 intercomparisons between manual sampling and continuous measurement were accomplished in yellow dust (YD) and non-yellow-dust (NYD) periods. The correlation coefficient for PM2.5 measurement was 0.91 in YD and 0.95 in NYD period. PM2.5 carbon measurement was correlated well at 0.95 for NYD period and moderately at 0.78 for YD period. PM2.5 sulfate got only YD comparison at 0.95 for correlation coefficient. For PM2.5 nitrate measurement, it showed a correlation coefficient at 0.8 for YD and 0.87 for NYD, respectively. Although a good correlation was found for instrument intercomparison, the values from continuous measurement are consistently lower than that from manual sampler. It was observed a great amount of transported dusts from significant YD events last year. This year, however, more PM2.5 in PM10 was observed and with a consistent high-and-low variation between PM2.5 and PM10.