A biocidal article includes a support having a first side and an opposing second side. A polymer layer including a polymer is adhered to the first side of the support; the polymer layer has an average layer thickness and a top surface. A plurality of biocidal particles are fixed within the polymer layer, the biocidal particles are coated by the polymer, the biocidal particles have a median particle diameter less than or equal to two microns, and the biocidal particles include a metal salt having soluble constituents. The average layer thickness is less than or equal to two times the median particle diameter, at least some of the biocidal particles extend beyond the average layer thickness from the support, and the polymer forms a semi-permeable membrane through which the soluble constituents percolate to the top surface.