A mathematical model was developed to predict time-dependent chemical composition and size distribution of indoor aerosols. The model can be used to predict aerosol characteristics in Southern California museums based on building parameters and data on outdoor aerosols. Using the Sepulveda House Museum in Los Angeles as a prototype museum, the model was used to test the effectiveness in reducing soiling rates of adding a conventional mechanical ventilation and particle filtration system; reducing ventilation rates, improving particle filtration; reducing deposition velocity to the surface being protected; limiting indoor aerosol sources; managing a site to maintain lowered outdoor aerosol concentrations; use of display cases or framing to reduce the rate of particle deposition on surfaces to be protected. The soiling rate can be reduced by at least two orders of magnitude by these measures. Combining improved filtration with either a reduced ventilation rate for the entire building or low air exchange display cases is very effective. Times to accumulate a perceptible deposit of soiling particles on walls and ceilings can be increased from years to centuries. Some of the measures are economically attractive, for instance by reducing costs to control indoor air temperature and relative humidity, or by decreasing cleaning costs.