Which statement about HEPA filtration is consistent with the material?

Which statement about HEPA filtration is consistent with the material?

• A. HEPA filters remove particles down to 0.2 microns
• B. HEPA filters remove particles down to 0.3 microns
• C. HEPA filters remove particles down to 0.4 microns
• D. HEPA filters remove particles down to 0.5 microns

Answer: (B)

HEPA filtration is rated at a particle size of 0.3 microns because that is the most penetrating size for these filters. A true HEPA filter is designed to capture at least 99.97% of particles at that 0.3-micron size. At sizes smaller than 0.3 microns, diffusion helps trap more particles, and at sizes larger than 0.3 microns, impaction and interception capture particles even more effectively. So the standard performance claim is centered on 0.3 microns, making the statement about removing particles down to 0.3 microns the correct one. The other specific micron values aren’t the rating used to define HEPA performance, even though the filter can still capture particles around those sizes.

HEPA filtration is rated at a particle size of 0.3 microns because that is the most penetrating size for these filters. A true HEPA filter is designed to capture at least 99.97% of particles at that 0.3-micron size. At sizes smaller than 0.3 microns, diffusion helps trap more particles, and at sizes larger than 0.3 microns, impaction and interception capture particles even more effectively. So the standard performance claim is centered on 0.3 microns, making the statement about removing particles down to 0.3 microns the correct one. The other specific micron values aren’t the rating used to define HEPA performance, even though the filter can still capture particles around those sizes.