Spun Melt Fiter Media Sample was clamped between cascade impactor and an aerosol chamber at a distance of 15 cms. Bacterial aerosol of bacteria -Staphylococcus aureus were generated in the chamber using the nebuliserassembly.Aerosols of test organisms of size 3 microns were drawn through the test mateial using a vacuumattached to cascade impactor. Postive control samples cllected aerosol wth no test specimen to detemine theupstream aerosol counts. Negative control was impermeable polyethylene sheet.The ratio of upstream to downstream was reported as Percentage Bacterial Filtration effciency. Following results are the Average of three readings.