Which description best characterizes HEPA filters?

Which description best characterizes HEPA filters?

• A. Filters that remove 99.97% of particles at 0.3 microns
• B. Filters that kill bacteria in air
• C. Filters that humidify air
• D. Filters that remove odors only

Answer: (A)

HEPA filters are defined by their high particle-capture efficiency. They are designed to remove at least 99.97% of particles that are 0.3 microns in diameter. This specific size is used in testing because it’s the most challenging to capture, so meeting this level ensures broad effectiveness for a wide range of particle sizes. The filters capture particles through interception, impaction, and diffusion as air passes through the filter fibers. They do not kill microorganisms, humidify air, or remove odors—those require other technologies. So the description that best fits HEPA filters is that they remove 99.97% of particles at 0.3 microns.

HEPA filters are defined by their high particle-capture efficiency. They are designed to remove at least 99.97% of particles that are 0.3 microns in diameter. This specific size is used in testing because it’s the most challenging to capture, so meeting this level ensures broad effectiveness for a wide range of particle sizes. The filters capture particles through interception, impaction, and diffusion as air passes through the filter fibers. They do not kill microorganisms, humidify air, or remove odors—those require other technologies. So the description that best fits HEPA filters is that they remove 99.97% of particles at 0.3 microns.