To assess the potential contributions of refineries to air pollution requires taking into account the formation of secondary pollutants, such as particulate matter (PM), resulting from the oxidation of emitted precursors. A plume-in-grid (PinG) model is best suited to address this issue, because it provides a realistic representation of the dispersion and transformations of the pollutants in the refinery plumes as they travel from the near field to long-range downwind distances. A PinG model that treats stack emissions as point sources and fugitive emissions as volume sources is applied here to a refinery in the Greater Paris region. The formation of secondary PM in the refinery plumes and the effect of hypothetical refinery emission controls on downwind PM concentrations are investigated. The simulation results emphasise the nonlinear relationships between emission levels and secondary PM species. These results imply that PinG modelling is recommended to correctly assess the potential impacts of refinery emissions on air pollution.