What is a HEPA filter's efficiency at capturing 0.3 micron particles?

A HEPA (High-Efficiency Particulate Air) filter is specifically designed to trap particles that are 0.3 microns in size with an efficiency of 99.97%. This means that when air is passed through a HEPA filter, it can capture at least 99.97% of airborne particles that are 0.3 microns in diameter. This level of efficiency is crucial for ensuring that the air is clean and free from harmful particles, making HEPA filters a standard in healthcare, clean rooms, and other environments where air quality is critical.

The significance of the 0.3 micron particle size is related to the most penetrating particle size (MPPS) for HEPA filters. It is at this size that particles are most likely to pass through the filter rather than being trapped. However, due to their design and the mechanisms through which they operate (including inertial impaction, interception, and diffusion), HEPA filters still maintain an exceptionally high efficiency at capturing these particles. This distinguishes HEPA filters from other types of filters that do not achieve such a high level of particulate removal.