Common questions about performance, room sizing, running costs and UK certifications.
What is an air purifier?
An air purifier draws room air through a filter — True HEPA, activated carbon, or both — removing airborne particles such as pollen, pet dander, dust, mould spores and smoke. Performance is measured by CADR (Clean Air Delivery Rate) in m³/h. A CADR of 246 m³/h means 246 m³ of fully cleaned air per minute. True HEPA captures 99.97% of particles ≥0.3 microns; activated carbon adsorbs gases and odours. For UK buyers the relevant certification standards are Allergy UK Seal of Approval, ECARF Quality Seal, and EN 1822 (the European HEPA grading standard). The running cost — electricity at the Ofgem rate (24.5p/kWh) plus filters — is often higher than the purchase price over three years.
Which is the best air purifier in the UK in 2026?
The Levoit Core 300S is the best air purifier for most UK bedrooms: £84.99 unit price, 12 m² at 3 ACH, 24 dB in sleep mode, 3-year total cost £230.70 at the Ofgem rate — the lowest 3-year total in our dataset. For ECARF-certified allergy relief in a medium bedroom, the Coway Airmega 150 (18 m², 20 dB, £287.15 over 3 years) is the better pick. For rooms above 20 m², the Levoit Core 400S covers 25 m² at 3 ACH for a 3-year total of £363.57.
How do I size an air purifier for my room?
Formula: CADR needed (m³/h) = room area (m²) × ceiling height (m) × target ACH. For a 15 m² bedroom with 2.4 m ceilings at 3 ACH: 15 × 2.4 × 3 = 108 m³/h minimum. Buy 20–30% above the minimum for filter ageing and real-world airflow resistance. Manufacturers' room size claims often assume 1–2 ACH — too low for allergy relief. Use the CADR calculator on this site to calculate at 3, 4 and 5 ACH for your exact room.
What is EN 1822 and does it matter?
EN 1822 is the European standard for HEPA filter testing. It grades filters from H10 (85% efficiency at 0.3 µm) to H14 (99.995%). "H13-grade claimed" without EN 1822 certification means the manufacturer asserts H13 performance but has not had it independently verified to the European standard. Philips is the main brand in the UK dataset with confirmed EN 1822 H13 certification on the 3200 AC3220/10 and 3000i AC3033/30. For allergies and asthma, verified H13 or above is the correct standard.
What is the difference between Allergy UK Seal and ECARF?
Both are independent certifications for allergy sufferers, but from different bodies. The Allergy UK Seal of Approval is awarded by the British allergy charity Allergy UK after independent product testing. ECARF (European Centre for Allergy Research Foundation) is a German-based certification used across Europe. In our UK dataset, the Coway Airmega Mighty holds the Allergy UK Seal; the Coway Airmega 150 holds the ECARF Quality Seal. Neither certification is "better" — they test by different protocols. Both confirm independent third-party allergy testing.
How much does it cost to run an air purifier in the UK?
At the Ofgem Q1 2026 rate of 24.5p/kWh and 12 hours/day run time, electricity costs range from £5.37/year (Blueair Mini Max, 5W) to £49.36/year (Blueair Blue Pure 211i Max, 46W). Filter costs dominate for most models: the Blueair Blue Max 3250i costs £70.00/year in filters versus £21.46/year in electricity. The Levoit Core 300S costs £39.98/year in filters and £8.59/year in electricity — a total annual running cost of £48.57. Always calculate the 3-year total (unit + filters + electricity), not just the sticker price.
Do air purifiers help with mould?
Air purifiers capture airborne mould spores (1–20 µm) — True HEPA captures them efficiently. They do not remove existing surface mould, and they do not address the underlying damp that causes mould growth. In UK homes with damp, the Meaco Arete Two combines a compressor dehumidifier with HEPA filtration in one unit — this is the correct tool when both moisture reduction and spore capture are needed. A standalone air purifier in a damp room is incomplete; moisture control comes first.
Are air purifiers worth it in the UK?
Yes — if correctly sized and in the right use case. A Levoit Core 300S in a 12 m² bedroom running 12 hours/day at 3 ACH costs £48.57/year all-in and delivers measurable reduction in airborne allergens within hours. The same machine in a 30 m² open-plan living room delivers under 1 ACH and provides almost no measurable benefit. The most common reason air purifiers disappoint is undersizing — not a bad product. Size to the room first.
