The development of a novel method for directional dust monitoring

Dust monitoring using sticky pads was popularised in the 1980s. The discolouration caused by dust adhering to white adhesive material was measured with a smoke stain reflectometer. This loss of reflectance was expressed as the percentage effective area coverage (EAC%) per day. EAC% can be used as a measure of nuisance caused by dust. EAC% may also be measured with a hand-held Sticky Pad Reader (SPR). Sticky pads can be mounted on flat or cylindrical surfaces to measure dust by deposition or in flux. An alternative method was developed in the 1990s that measured total dust coverage using computer-based scanning. DustScan used a transparent adhesive film wrapped around a vertical cylinder with magnetic north marked. The sticky pad was sealed with another transparent sheet before scanning at 50 dots per inch (dpi). Dust levels were assessed by comparing the grey-scale values of pixels in the exposed area with an unexposed reference area. Insects and other extraneous material could be 'masked out' from the computer analysis. Dust coverage was expressed as percentage absolute area coverage (AAC%). DustScan has subsequently been developed commercially. A limited trial indicated that monitoring periods of 7-14 days were preferred to avoid dust saturation of the sticky pad. A method for calculating EAC% has been developed and shown to have a high degree of correspondence with an SPR. A trial for the Minerals Industry Research Organisation (MIRO) made comparisons between DustScan and other dust monitoring methods. Dust nuisance limits based on AAC% and EAC% are proposed.par.