The Stochastic Human Exposure and Dose Simulation for Particulate Matter (SHEDS-PM) is a population exposure and dose model for particulate matter developed by the US EPA's National Exposure Research Laboratory (NERL). SHEDS-PM uses a probabilistic approach to estimate distributions of PM exposure and dose for a specified population based on PM concentrations supplied as input to the model. SHEDS-PM is intended to be used for providing estimates of the range in exposure and dose across a population (variability), and the likelihood of exposures above a particular level. The stochastic basis for the model also allows for the uncertainty in any given percentile of the exposure or dose distribution to be estimated. SHEDS-PM is driven by a graphical user interface (GUI) that allows the user to specify most inputs needed by the model. At minimum, the user is expected to supply a database of ambient outdoor PM concentrations for the population of interest. Additional inputs required include distributions for the parameters of equations used to estimate microenvironmental PM concentrations based on the ambient outdoor PM concentration and smoking prevalence data (if exposure to environmental tobacco smoke is included in the model run scenario).