Pollen allergies, fine dust, odors or viruses — air purifiers promise a lot. But which technology is truly effective? This guide separates fact from marketing.
The 4 Purification Technologies Explained
HEPA Filter (High Efficiency Particulate Air)
This is the reference technology. A HEPA 13 filter retains 99.97% of particles 0.3 microns and larger — pollen, dust mites, mold spores, bacteria. This is the minimum recommended for allergy sufferers.
Activated Carbon
Complementary to HEPA, the activated carbon filter absorbs VOCs (volatile organic compounds), odors (cooking, tobacco, pets) and gases. Most effective purifiers combine HEPA + activated carbon.
Ionizer
The ionizer emits negative ions that charge particles and make them fall on surfaces. Limited effectiveness and risk of ozone production (a lung irritant). Avoid if you have asthma.
UV-C Lamp
UV-C light destroys the DNA of bacteria and viruses. Useful as a complement to HEPA, but of no value if used alone.
CADR: The Key Indicator
CADR (Clean Air Delivery Rate) measures the volume of clean air delivered per hour. Formula: CADR = room area (m²) × height (m) × 2.5.
| Room size | Min. CADR | Recommended CADR |
|---|---|---|
| 15 m² | 90 m³/h | 150 m³/h |
| 25 m² | 150 m³/h | 250 m³/h |
| 40 m² | 240 m³/h | 375 m³/h |
Frequently Asked Questions
When should filters be replaced?
The HEPA filter is generally replaced every 12 months (with daily 8h use). The activated carbon filter wears faster: every 6 months.
Is an air purifier useful against viruses?
HEPA 13 purifiers combined with a UV-C filter can reduce viral load in indoor air, according to multiple studies (EPA, ASHRAE 2021). They do not replace ventilation but are a useful complement in enclosed spaces.