How HEPA filter works
A HEPA filter stops different-sized particles in various ways. Large particles are too big to pass through the gaps in the filter, so they get stuck. Smaller particles (things like bacteria, for example) get stuck to the fibres of the filter, preventing them from passing through.
And the smallest particles are caught via diffusion – being so small, they zoom around in zig-zagging movements instead of passing straight through the gaps in the filter, so they eventually get stuck in the filter’s fibres too.
HEPA filters are very effective and can even capture nanoparticles. That’s why they can remove 99.95% of particles from the air. But does the HEPA filter always stay this effective? Does it need any maintenance or cleaning?
