When does interception occur in air filtration?

Interception occurs in air filtration when particles closely match the size of the fiber. In this process, the airflow carries particles through the filter, and when a particle's trajectory brings it into close proximity with a fiber, the particle is captured due to the adhesive forces acting between the fiber and the particle. This mechanism is particularly effective for particles that are similar in size to the filter media, as their paths are more likely to intersect with the fibers, leading to effective filtration. This contrasts with other mechanisms like inertial impaction or diffusion, which also contribute to filtration but depend on different physical phenomena. Understanding interception is crucial for evaluating filter efficiency and determining proper filter design and application.