Passive sampling technique is used to determine the concentration of gas in the atmospher, for example, NO2 and SO2. Borisuttichun (2008) construct the test kit for determination of SO2 in ambient air by passive sampling. The polypropylene diffusion tube provided high precision and at the same time provided less percent error (high accuracy) in comparison with fluorescence technique. Moreover, 3 days exposure was found to be appropriate for measurement of SO2 in ambient air by the designed passive diffusion tube.