Air filters are most effective at removing particles of which size?

Air filters are designed to capture airborne particulate matter, which varies in size. Their effectiveness relies heavily on the mechanisms of particle capture, including inertial impaction, interception, and diffusion. Particles that are smaller than 5 micrometers are particularly challenging for the respiratory system, as they can penetrate deeper into the lungs and even enter the bloodstream.

Filters, especially high-efficiency particulate air (HEPA) filters, are specifically formulated to excel at trapping these smaller particles. The diffusion process works well at this size range, allowing the filter's fibers to capture these tiny particles more effectively due to their random motion in the air. This property is essential in various applications, particularly in environments that demand high air quality, such as hospitals, laboratories, and clean rooms.

In contrast, larger particles are less likely to penetrate deeply into the lungs, and as a result, many air filtration systems do not prioritize their capture as much as they do for smaller particles. This understanding of filtration efficiency is rooted in the physical principles governing particle behavior in air and the design specifications of the filters used.