Medical air filters shall be sized for 100% of the system peak calculated demand and be rated for a minimum of ______ efficiency at ______ micron or greater.

• A. 95% @ .5
• B. none of the above
• C. 98% @ .1
• D. 100% @ .1

Answer: (B)

Medical air filtration relies on achieving very high particulate removal while ensuring the system can support the full peak demand. The rating used for this purpose is a HEPA-level efficiency at the most penetrating particle size, typically 0.3 microns, which is about 99.97% efficient. That combination—100% of system peak demand and a 99.97% efficiency at 0.3 micron or better—is the standard to ensure clean, safe medical air.

The options given do not specify that HEPA-level performance at 0.3 micron. They list lower efficiencies or different micron sizes that do not meet the HEPA criterion. Therefore, none of the listed options match the required specification. In practice, you would specify a filter rated at least 99.97% efficient at 0.3 micron, sized for 100% of the system’s peak demand.