J. Aerosol Sci., Vol. 14, No. I, pp. 65 68, 1983. 0021 8502/83/010065 04 $03.00/0 Printed in Great Britain. ~: 1983 Pergamon Press Ltd. SAMPLING EFFICIENCY OF AEROSOL SAMPLERS FOR LARGE WIND-BORNE PARTICLES--A PRELIMINARY REPORT P. HOFSCHREUDER,E. VRINS and J. VAN BOXEL Department of Air Pollution, Agricultural University Wageningen, P.O. Box 8129, 6700 EV Wageningen, Netherlands (First received 31 March 1982 and in revised form 7 September 1982) Abstract--The feasibilityof assessing the sampling efficiency of aerosol samplers for large wind- borne particlesin the open air was determinedin a pilot study. The experiments with 17 gm diameter monodisperseaerosolsshow the low sampling efficiency of widelyused instrumentssuch as the EPA high volumesamplerand LIB sampler for a coarseaerosol.A new developed tunnel samplershowsa high sampling efficiency for this aerosol relativeto the Rotorod as a reference sampler. Additional experiments with different aerosol sizes and under varyingmeteorological situations are planned. During the last decade much research effort was devoted to assess the large particle sampling efficiency of aerosol samplers and specially designed inlets. Wind-tunnel experiments to develop sampling theory were performed by Raynor (1970), Belyaev and Levin (1974), Davies and Subari (1978), Lundgren et al. (1978), Zebel (1979), Durham and Lundgren (1980), Tufto and Willeke (1981), Jayasekera and Davies (1980) and Davies and Subari (1982). Wind-tunnel research on commercial instruments or prototypes was performed by Sehmel (1970), Pattenden and Wiffen (1977), McFarland et al. (1977), Wedding et al. (1977), Ogden et al. (1978), Wedding et al. (1980), and Liu and Pui (1981). Comparisons of sampling instruments using pre-existing aerosol in the open air were made by Friedrichs and Grover (1977), Baiulescu and Marinescu (1979), and Laskus et al. (1980). The only test of commercially available aerosol samplers in the open air with monodisperse aerosols, was conducted by May et al. (1976). They used sampling instruments important at that time. Sampling instruments widely used nowadays such as the EPA high volume sampler, LIB sampler (Landesanstalt Immissionsschutz Essen, BRD), a 47 mm filter holder and virtual impactor inlet were not tested and were not all available at that time. Field tests of aerosol sampling instruments with well defined test aerosols are very important since the intensity and structure of turbulence in the open air are thought to differ from those in wind-tunnels, due to limitations of the latter in size, and to wall effects. Large particle sampling characteristics are important because: ( 1 ) The proposed inspirability curve for aerosols by ISO-TC 146 (1981) extends to 180/~m diameter. (2) Models for dispersion and deposition of aerosols should be validated by measure- ments of total suspended particles (TSP). (3) Source strengths of fugitive dust sources can only be estimated by TSP measurements. In 1978 the Dutch Study Group on Aerosols initiated a research project on the sampling efficiency of aerosol samplers under field conditions in which the Air Pollution Department of the Agricultural University Wageningen, the Atomic Research Establishment, Mol (Belgium), the Netherlands Energy Research Centre, Petten, the Prince Maurits Laboratories TNO, Rijswijk, and the Institute for Environmental and Occupational Hygiene TNO, Delft, participated. The experimental set-up consisted of an emission line, per- pendicular to the wind direction, consisting of three spinning-top generators (May, 1966) producing monodisperse dioctylphthalate (DOP) aerosols and three SF 6 tracer gas emission units. The aerosol sampling line (Fig. 1) was located parallel to the emission line at a distance 65