HEPA (High Efficiency Particulate Air) is an air filtration standard. Filters meeting the HEPA standard must satisfy certain levels of efficiency. There are two similar standards. ASME, U.S. The DOE standard requires that HEPA air filters must remove—from the air that passes through—at least 99.97% of particles whose diameter is greater than or equal to 0.3 µm. The European standard is that the filter removes at least 99.95% of the most penetrating particle size. The Atmosphere Mini Treatment System filter has been shown to meet each of these standards and even exceed the standards.