Health-related sampling is required for risk assessment of personal exposure to dust. Foams are used for sampling the thoracic and respirable dust fractions, but there is a limit in dust holding capacity of the foams. This study supply data on the holding capacity of foams. The size selector tested incorporated two stages in series followed by a back up filter. The first stage was a 30 ppi foam (thickness 10 mm) and the second stage was a 90 ppi foam (thickness 30 mm). At a Face velocity of 0.13 m/s the foams mimic the ISO-CEN penetration curves for the thoracic (30 ppi foam) and respirable (90 ppi foam) dust fractions. The dust holding capacity of the size selector was tested for non-neutralized dust generated from nine different materials and the capacity was low ( < 1 mg/cm(2) race area) for five of the materials. The highest capacity observed was 10 mg/cm(2) face area. (C) 2000 Elsevier Science Ltd. All rights reserved.