AEROSOL EVALUATION DIFFICULTIES DUE TO PARTICLE DEPOSITION ON FILTER HOLDER INNER WALLS

The analysis of aerosol particles collected on aerosol samplers is most generally performed on the filter alone. A chemical digestion method, performed directly inside the filter cassette avoids any external pollution or sample loss due to handling. A systematic comparison of these two methods, performed on different industrial sites, demonstrates that a sometimes significant fraction of the sampled aerosol deposits on the inner cassette walls, resulting in severe underestimation of the occupational hazard with the first method. A review of published laboratory studies clearly indicates that every particle entering the cassette is part of the sample. As deposits on the walls are not usually taken into account, standards and commonly used practices should be reviewed to accommodate these observations. © 1990 British Occupational Hygiene Society.