Are air purifiers safe?
In one line: yes — a mechanical filter (HEPA/MERV-13) air purifier is safe to run continuously, including in a bedroom, nursery or around pets. The one category to avoid is ozone-generating devices (some ionisers), because ozone is a lung irritant.
Filter-based purifiers are safe
The vast majority of home purifiers simply pass air through a HEPA or MERV-13 filter — a purely mechanical process with nothing emitted into the room. They're designed for continuous use, safe to leave on overnight, and safe around children and animals. Normal electrical safety applies: use a certified unit (look for recognised marks), keep cables tidy, and site it where it can't be knocked over.
The exception: ozone
Some ionising, "plasma" or "activated oxygen" devices produce ozone, which irritates the lungs and can worsen asthma — best avoided in occupied rooms, and especially around babies, the elderly and pets (birds are very sensitive). Stick to a mechanical filter, or an ioniser only if it's clearly ozone-free / CARB-compliant. See ionisers & ozone and UV-C.
Common safety questions
- Babies & nurseries: safe and often beneficial — choose quiet and ozone-free (nursery guide).
- Pets: filter units are safe for cats, dogs and even birds; avoid ozone (pets guide).
- Leaving it on 24/7: fine for a filter unit — that's how they're meant to be used.
- Do they release anything harmful? Filter units don't. Only ozone-generating devices are the concern.
Next step
See safe, ozone-free, filter-based units at Best Air Purifier UK.
FAQ
Are air purifiers safe to breathe / run all the time? Yes for filter-based units — they emit nothing; they just remove particles. Continuous use is intended.
Which air purifiers are not safe? Ozone generators and some ionisers that produce ozone. Choose a mechanical filter or a clearly ozone-free model.