An objective data quality assurance scheme, which can be coded algorithmatically, is developed to validate measurement of ambient sulfur dioxide data. The essential feature of the scheme is a set of data rejection criteria imposed for one minute, three minute, hourly, and twenty‐four hour averaged sulfur dioxide concentrations. The scheme also includes (i) correction of any time drifts, (ii) corrections of span and zero drifts, and (iii) conversion of the digital information on sulfur dioxide levels into absolute concentrations. The scheme was incorporated in a data processing software and implemented in a sulfur dioxide monitoring network. The data obtained from the initial four‐month monitoring period were reported. It is found that the data quality assurance scheme works well; all suspicious data have been rejected and most of the rejected data are those collected during equipment breakdown periods.