Oxides and acids of nitrogen play an important role in regulating atmospheric radical levels, in particular, that of the OH radical the main initiator of the degradation of chemicals in the atmosphere. A comprehensive overview on the methods used to measure nitrogen oxides and acids in the troposphere is given and difficulties and artefacts associated with the use of the techniques for measurements in urban and mega city environments is illustrated. State-of-the-art methods for the measurement of OH and HO2 radicals are reviewed and recently recognised difficulties, in particular with the...

Oxides and acids of nitrogen play an important role in regulating atmospheric radical levels, in particular, that of the OH radical the main initiator of the degradation of chemicals in the atmosphere. A comprehensive overview on the methods used to measure nitrogen oxides and acids in the troposphere is given and difficulties and artefacts associated with the use of the techniques for measurements in urban and mega city environments is illustrated. State-of-the-art methods for the measurement of OH and HO2 radicals are reviewed and recently recognised difficulties, in particular with the...