A HEPA vacuum is capable of filtering particulates of 0.3 microns or greater to what efficiency?

A HEPA vacuum is capable of filtering particulates of 0.3 microns or greater to what efficiency?

• A. 99.5%
• B. 99%
• C. 99.9%
• D. 99.97%

Answer: (D)

HEPA filters are rated to capture the most challenging particle size, about 0.3 microns, with the highest efficiency. This size is called the most penetrating particle size, and at this point the filter must remove 99.97% of particles. For 0.3 microns or larger, the efficiency stays at least 99.97% because larger particles are captured even more easily by mechanisms like impaction and interception, while smaller particles are helped by diffusion. That’s why 99.97% is the correct benchmark for a HEPA vacuum. The other options fall short of the standard minimum expected for HEPA performance.

HEPA filters are rated to capture the most challenging particle size, about 0.3 microns, with the highest efficiency. This size is called the most penetrating particle size, and at this point the filter must remove 99.97% of particles. For 0.3 microns or larger, the efficiency stays at least 99.97% because larger particles are captured even more easily by mechanisms like impaction and interception, while smaller particles are helped by diffusion. That’s why 99.97% is the correct benchmark for a HEPA vacuum. The other options fall short of the standard minimum expected for HEPA performance.