Abstract: The invention relates to a downdraft paint booth having an overspray filtering system integral with the floor grates, and to the floor grate filters themselves. The grates have a load bearing frame portion having enclosed within it an integral or removable recyclable filter. The filter is preferably metallic and of a construction that will withstand baking in a high temperature oven to reduce captured overspray particles to an inert ash. Alternatively, the combination floor grate filters may be cleaned of paint residue by immersion in a suitable solvent or chemical bath. The floor grate filters will have 95-99% efficiency at removing airborne particulates. Secondary filters may be used after the combination floor grate filters to remove any final over-spray passing the filters. Typically, the floor grate fillers will go through five to ten cleaning cycles before he secondary filters would need replacement.