cross linking agent such as those previously described as being preferred for polymerization of acrylic acid a fibrous substrate having a coating of cross linked cellulose ether may be fabricated as follows a pre polymer solution is prepared from hydroxymethyl cellulose which is commercially available under the trade name natrosol u00ae from hercules chemical co and a cross linking agent preferred cross linking agents are melamine formaldehyde resins urea formaldehyde resins such as kymene u00ae available from hercules chemical co and dimethylolurea an especially preferred cross linking agent is kymene u00ae 917 in combination with an ammonium chloride catalyst 10 wt with respect to kymene u00ae the fibrous substrate is immersed in and removed from or sprayed with the pre polymer solution the fibrous substrate is then dried and cured at 80 u00b0 c for two hours the resulting fibrous substrate having a coating of gel forming polymer may subsequently be contacted with a surfactant laden oil to produce an anti pathogenic air filtration medium alternatively the oil and surfactant can be added to the pre polymer solution the anti pathogenic filter with a coating of gel forming polymer is further illustrated with a metal colloid suspension certain metal colloidal suspensions specifically silver and copper and more particularly silver have demonstrated anti pathogenic activity against a broad spectrum of bacterial.