Relative efficiency of passive dust samplers: progress towards coarse dust dispersion modelling

The collection efficiency of the DustScan DS100 directional sticky pad dust gauge has been analysed in order to estimate airborne dust concentrations for use in atmospheric dispersion models. A DS100 directional sticky pad dust monitor was tested for 10 months at a quarry boundary with respect to a Wilson and Cook (WAC) sampler, with comparisons primarily made with regard to directional wind speeds over the relevant monitoring periods, as recorded by an on-site meteorological station. The mass of dust collected using the DS100 monitor fluctuated between 3.1% and 21.3% of that caught by the WAC sampler over each period. Variations in collection efficiency were modelled using the count of wind speeds per half hour period and two distinct periods were observed. The main trend showed that higher wind speeds decreased relative DS100 efficiency, with low wind speed (<3 m/s) and high wind speed (>5 m/s) periods showing modelled efficiency above 10% and below 5% respectively in comparison to the WAC sampler. However, a central period of 9 weeks during the monitoring study showed a reverse of this pattern, with significant wind speeds over 5 m/s correlating with higher DS100 efficiency. Although dust catch on each sampler varied significantly over the study period, an average DS100 efficiency of approximately 7% in comparison to the WAC is suggested for use in estimating airborne dust concentrations for use in atmospheric dispersion models.