Soiling measurements are needed to address strategies to control dust and determine its sources. There is no widely recognized method for dust monitoring in museums, but we used sticky samplers to collect deposited coarse particulate matter, and both manual microscopic observations and image analysis for determining soiling potential in the museum environment. We adopt fractional area covered by deposited particles as a surrogate for soiling and the covering rate (unit: s−1) as a measure of the rate of soiling. It was clear that visitor flow was a major contributor to soiling, such that soiling mechanisms in different museums could be compared after measurements were normalised on a per capita basis. The proximity of visitors to objects was another important factor with the soiling declining with distance from visitor pathways (a half-distance of about 0.5 m), which suggests soiling of objects on open display could be reduced by increasing the distance from visitors.