Not all HEPA filters are created equal. Only by using the EN1822:2019 and ISO 29463 test standards can end users really identify whether a HEPA filter has been manufactured and designed to fit the clean air requirements of their workplace. The EN1822 standard has had many iterations dating back to its original inception in the 1990s. In the latest iteration of this standard, the test procedure for ISO 29463 has been included to ensure global acceptance of the test. Whether the HEPA filter is used for controlled environments like cleanrooms or as part of a system upgrade in a HVAC system or in a standalone air cleaner, you should always check that the filter has been individually certified to these standards.
A HEPA filter's rating only means something if every single filter is verified — not just a sample pulled from the batch. Filtration efficiency is at its lowest against the most penetrating particle size (MPPS), typically between 0.1 and 0.2 microns, so a filter can perform well against both larger and smaller particles yet still fail at the MPPS if there is a pinhole leak or a flaw in the media or seal. EN 1822 and ISO 29463 address this by requiring efficiency to be measured precisely at the MPPS, and by allowing individual scan-testing that maps the entire filter face for local leaks rather than reporting a single average value. This is why Camfil scan-tests 100% of its HEPA filters instead of relying on batch sampling — so the H13 or H14 rating printed on the label reflects the exact filter you install, not a statistical estimate of the production run.
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