Objects in Southern California museums may become perceptibly soiled within periods as short as a year due to the deposition of airborne particles onto their surfaces. Methods for reducing the soiling rate include reducing the building ventilation rate, increasing the effectiveness of particle filtration, reducing the particle deposition velocity onto surfaces of concern, placing objects within display cases or glass frames, managing a site to achieve low outdoor aerosol concentrations, and eliminating indoor particle sources. A mathematical model of indoor aerosol dynamics and experimental data collected at an historical museum in Southern California are combined to illustrate the potential effectiveness of these control techniques. According to model results, the soiling rate can be reduced by at least two orders of magnitude through practical application of these control measures. Combining improved filtration with either a reduced ventilation rate for the entire building or low-air-exchange display cases is a very effective approach to reducing the soiling hazard in museums.