What to look for before you buy
Choose an air purifier that works
A good purifier can clearly cut the fine dust (PM2.5) in a room. A badly chosen one barely makes a difference. Here's how to pick well.
- 1
Look for 'True HEPA' (H13)
This filter catches fine soot and dust from traffic, smoke and cooking. Avoid vague labels like 'HEPA-type'.
- 2
Match the CADR to your room
CADR is how much clean air it makes per hour. Rough guide: a 20 m² bedroom needs about 250 m³/h. Bigger room, bigger number.
- 3
For traffic gas, add carbon
HEPA can't trap NO₂. Only a thick activated-carbon filter (often 1 kg or more) helps with gases. A thin carbon sheet does little.
- 4
Check it's quiet enough
You'll only use it if you can sleep next to it. Look for under 35 dB on the low setting for bedrooms.
- 5
Budget for filters
Replacement filters can cost £30–£80 a year. Check the price before you buy the machine.
- 6
Skip ozone and ioniser gadgets
Some 'air fresheners' and ionisers release ozone, which irritates the lungs. Health agencies advise against them.
Where to compare purifiers
We don't sell or recommend specific brands and earn nothing from these links. Independent tests are the best guide.