Development of a filter set for breathing filters

We have studied the filter materials in the most popular foreign breathing filters. We have established that the filter set for a bacterial/viral heat and moisture exchange (HME) filter consists of a primary filtering layer which provides highly efficient removal of bacteria and viruses from the air as a result of mechanical or electrostatic filtration; barrier layers, preventing migration of fibers and moisture droplets into the primary filtering layer; and a heat and moisture exchange layer, providing the needed humidity and temperature for the air inspired by the patient. As a result of our studies, we have selected or designed de novo filter materials to make a filter set for a domestic breathing filter. We have determined the parameters of the material for the heat and moisture exchange layer: weight percent of fibers, thickness, surface and volume density, air permeability, hygroscopicity, weight percent calcium chloride.