Monitoring acidic air pollutants near Rome by means of diffusion lines: development of a specific quality control procedure

A quality control procedure was developed for acidic air pollutant monitoring using diffusion lines (a series of annular diffusion denuders followed by a filter pack). The procedure covers the main stages involved in obtaining concentration data using this technique, i.e. preparation of the diffusion lines, sampling, chemical analysis of the samples and overall data analysis. This QC procedure was applied to a 1-yr programme for monitoring daily levels of HCl, HONO, HNO3, SO2, NH3 and related salts in a rural site near Rome. Applying the QC procedure led to production of a good-quality data set, thus confirming the reliability of this technique.