What is the smallest sized particle that HEPA filters are able to remove?

What is the smallest sized particle that HEPA filters are able to remove?

• A. 0.2 microns
• B. 0.3 microns
• C. 0.4 microns
• D. 0.5 microns

Answer: (B)

HEPA filter performance is defined using a particle size around 0.3 microns because this is the most penetrating size—the hardest to capture. At this size, the filter’s efficiency is about 99.97%, which is the standard performance specification. Smaller particles are captured very well too, mainly by diffusion as they zigzag and bump into fibers, while larger particles are captured more easily by impaction and interception due to their inertia. So, while HEPA filters can remove particles smaller and larger than 0.3 microns, the 0.3-micron size is the benchmark used to rate their effectiveness. That’s why 0.3 microns is the best answer.

HEPA filter performance is defined using a particle size around 0.3 microns because this is the most penetrating size—the hardest to capture. At this size, the filter’s efficiency is about 99.97%, which is the standard performance specification. Smaller particles are captured very well too, mainly by diffusion as they zigzag and bump into fibers, while larger particles are captured more easily by impaction and interception due to their inertia. So, while HEPA filters can remove particles smaller and larger than 0.3 microns, the 0.3-micron size is the benchmark used to rate their effectiveness. That’s why 0.3 microns is the best answer.