HEPA filters operate based on three primary mechanisms: interception, impaction, and diffusion. Interception occurs when particles follow a line of flow in the air stream and come within one radius of a fiber and adhere to it. Impaction is when larger particles are unable to avoid fibers by following the curving contours of the air stream and are forced to embed in one of them directly. Diffusion is a process that enhances capture of very small particles as they are bombarded by gas molecules, causing them to deviate from the air stream and collide with filter fibers.
