J. Environ. Monit., 1999, 1 53N AIRMON ’99, The Third International Symposium on Modern Principles of Air Monitoring This issue includes 20 papers presented at AIRMON 99, Geilo, in Norway, February 10–15, 1999. The previous AIRMON meetings were held in Geilo in 19931 and in Sa�len, Sweden, in 1996.2 The symposium, as with previous meetings in this series, was organized by the National Institute of Occupational Health (NIOH), Oslo, Norway and the National Institute ofWorking Life (NIWL) in Umea°, Sweden.The meeting focused on the increasing requirement of air monitoring within the preventive framework of identifying and controlling health hazards in the work place and in the environment. For the characterisation of exposure to chemical and biological agents, sensitive, selective and user-friendly methods and relevant sampling and monitoring strategies are needed.The plenary programme was planned with a view to providing a comprehensive overview of the latest developments in this scientific field. There were 146 registrants representing 17 countries. Over the four days symposium, a total of 27 invited lectures were presented in five sessions: (1) Exposure Assessment—Strategies and Methodologies; (2) Aerosols; (3) Gases, Vapours and Mixed Phases; (4) Low Level Exposure—Indoor and chemical contaminants which occur simultaneously in vapour and aerosol form.Of special interest were inorganic gases, complex mixtures of isocyanates and water-mixed metal working fluids. Biosensors in air monitoring achieved considerable interest.In session 4 dispersion models in the estimation of both population and individual exposures were discussed. Such methods have been used in Norway, both for cross-sectional studies and for panel studies, and both in areas with industrial pollution sources and with traYc pollution as the primary source. Measuring strategies and monitoring of ambient and indoor-air for ozone and volatile organic compounds were also reported.Finally, session 5 was devoted to European regulations and international method standardisation and harmonisation. The 38 poster presentations dealt with on-site analysis, new methodologies for measurements of a broad range of chemical compounds and bioaerosols and exposure assessment in a variety of occupations, completed the scientific programme.We gratefully acknowledge the financial support fromthe commercial companies exhibiting their latest air monitoring equipment during the conference. Special thanks are extended to Siri Hetland,MargaretaKarlsson and Margaret Rhen, members of the Organising Committee, for their excellent administrative and organisational handling of the details and their care of everyone during themeeting.The symposium format with mid-day outdoor activities (12.00 to 16.00 hrs), which is much appreciated by the participants, will be continued. Plans have been set in motion to hold the Fourth AIRMON symposium in Sweden, in February 2002. 1 Analyst, 1994, 119, 1–107 2 Analyst, 1996, 121, 1151–1305 Yngvar Thomassen National Institute ofOccupationalHealth Oslo, Norway J.O.Levin National Institute for Working Life Umea° , Sweden Ambient Air and (5) International Regulations, Standardisation and Quality Assurance. Session 1 focused on data needs for epidemiology and the evolution of strategies for exposure assessment. Variation in workplace monitoring programmes and self-assessment of chemical exposure were also highlighted. Session 2 on Aerosols was very ably started with a lecture from Professor James Vincent, who was later recruited to JEMas the US Associate Editor (see overleaf ).The session dealt with recent advances in aerosol sampling towards the development of improved sampling devices, sampling and characterisation of nano-size aerosols and individual particles. A novel instrument for personal, time-resolved concentration monitoring and sampling of the inhalable, thoracic and respirable fractions were also presented. Based onmanikin aspiration eYciency in calm air, results were reported which suggests that the current personal inhalable samplers are unsuitable for the measurements of particle sizes greater than the current maximum size of the inhalable convention (diameter=100 mm). Session 3 was devoted to the complexities in sampling and measuring Preparation for the evening session during AIRMON ’