Microbially Tested HEPA Filters

　　Microbially tested simply means that a filter was tested against a particular bacterial, fungal, or viral particle challenge. Many industry and university studies have shown that a HEPA filter provides the same removal efficiency against a viable or a non-viable particulate challenge of the same size. The physical laws at work governing the removal efficiency of a filter media do not discern between a viable and a non-viable particle. The same capture mechanisms apply. Thus, the removal efficiencies for a viable and a non-viable particle are equivalent. The removal efficiency of the HEPA media against a 0.027 micron viral particle is dominated by the diffusion filtration mechanism. This mechanism provides a very effective means of removing very small particles, such as viruses. In fact, the smaller the particle, the higher the removal efficiency due to the diffusion filtration mechanism.