What HEPA means
High-efficiency particulate air. It's a filter standard, not a brand. The grade tells you what share of particles the filter catches at the size that's hardest to trap.
The grades
| Label | Catches at least | Notes |
|---|---|---|
| E12 | 99.5% | “Efficient” grade, not true HEPA |
| H13 | 99.95% | Plenty for most homes |
| H14 | 99.995% | Worth it for bad allergies or asthma |
| True HEPA | 99.97% at 0.3 µm | US wording, tested a different way; broadly similar to H13 |
E and H grades come from the European standard EN 1822.
“HEPA-type” and “HEPA-style”
There's no standard behind these words. The filter may still be good; Levoit's is, for example. But the label promises nothing, so look for lab test results instead.
Grade versus speed
An H14 filter in a slow unit cleans less air than an H13 filter in a fast one. For a room, the clean air delivery rate (CADR) matters more. Sealing matters too: air that leaks around the filter isn't filtered.
Work out the CADR your room needs
Looking after a HEPA filter
- Don't wash it unless the maker says you can.
- Vacuum the pre-filter monthly in summer.
- Replace it every 6 to 12 months, sooner after heavy smoke. Set a reminder.
- Buy genuine or well-reviewed filters. Cheap copies may not seal properly.