WOUIRG PARTY I: AlIALYSIS or POLLUTAIITS Chairman: A. LIBERTI (CNR - Roma, I) Summary by the Chairman 3 Detection of gaseous nitric acid by OH (A~X) - fluorescence gen­ erated by ArF-laser irradiation Th. PAPENBROCK and F. STUHL 5 Preparation of standard atmospheres of nitrogen acid compounds: the N02 permeation tube I. ALLEGRINI, P. BUTTINI, V. DI PALO and M. POSSANZINI 15 Automated denuder systems J. SLANINA, A. M. VAN WENSVEEN, C. A. M. SCHOONEBEEK and P. I. VOORS 25 A battery-powered light-weight ozone analyzer for use in the troposphere and stratosphere S. SARAND, W. SPEUSER and U. SCHURATH 33 H202 in solid precipitation A. NEFTEL, A. SIGG and P. JACOB 45 Detection of nitrated and oxygenated polyaromatic hydrocarbons (PAR) in suspended particulate matter sampled in urban areas and their relation with anthropogenic emission and photochemical smog formation A. CECINATO, E. BRANCALEONI, C. DI PALO, R. DRAISCI and P. CICCIOLI 58 Field intercomparison of sampling and analytical methods for S02 and S04 in ambient air K. NODOP and J. E. HANSSEN 69 Field measurements on the use of denuders for the evaluation of acid deposition Istituto sull'Inquinamento Atmosferico del C. N. R. , Mon- rotondo, Italy 79 -vii- Use of air - S02 mixtures for intercomparison of S02 monitors in the EEC M. PAYRI S SAT , H. RAU and G. SERRINI 103 Determination of polychlorinated dibenzo-P-dioxins and dibenzofurans in outdoor air P. KIRSCHMER and M.