How to Choose an Air Purifier for Smoke, Pet Hair and Odours
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An air purifier can make a real difference to dust, pet hair and smoke particles in a room, but only if it suits the space and you keep its filter fresh. Here's what to look for, in plain English.
What an air purifier can and can't do
A portable air purifier pulls room air through filters. Most are built to catch particles: dust, pollen, pet dander and the fine particles in smoke. Smells and gases need a different kind of filter, usually activated carbon.
The US Environmental Protection Agency puts it simply: no air cleaner removes every pollutant, and none fixes the cause of damp or mould. Keep opening windows, use the cooker hood when you cook, and deal with any damp as well.
HEPA: the filter to look for
HEPA stands for high-efficiency particulate air. A true HEPA filter catches a very high share of tiny airborne particles, which is why the best-rated purifiers tend to use one. In Europe, HEPA filters are graded H13 or H14. Be wary of vague wording such as "HEPA-type" or "HEPA-style".
Carbon filters for smells
If cooking smells, pet odours or the smell of smoke are the main problem, choose a purifier with an activated carbon filter as well as HEPA. Carbon traps some of the gases and odours that a particle filter lets through, and the more carbon there is, the better it tends to work.
Size it to your room with CADR
CADR (clean air delivery rate) tells you how much filtered air a purifier delivers. The higher it is, the faster it cleans a room. The EPA's rule of thumb is a CADR of at least 195 cubic feet per minute for a 300 sq ft room. In metric, with a standard 2.4 m ceiling, that's roughly 12 m³/h of CADR for every square metre of floor, so a 15 m² bedroom needs about 180 m³/h. For high ceilings, or to clean the room faster, go bigger, and check the maker's recommended room size.
What to avoid
- Purifiers that deliberately produce ozone, sometimes sold as "ozone generators". Ozone irritates the lungs, and the EPA advises against them.
- Models with no clear information on the filter type, replacement filters or room size.
Running costs and noise
Every filter needs replacing. Follow the maker's replacement schedule, change the filter sooner if it looks dirty, and check that replacement filters are easy to buy before you choose a model. If the purifier will run in a bedroom, look at how loud it is on its lowest setting and whether it has a sleep mode.
Where to put it
Stand it where air can flow freely, away from walls and furniture, in the room you use most. For most people that's the bedroom or the living room. Close the doors while it runs if you want that room cleaned quickly.
Our air purifier
Our HEPA Air Purifier for Smoke, Odour and Pets is a compact, USB-powered unit for a desk, bedside table or small room. The maker says it suits spaces of up to about 20 m², runs at about 20 dB in sleep mode, and has a filter that meets HEPA standards plus an activated carbon layer for smells. For a large living room, choose a bigger purifier with a higher CADR.
Quick answers
Does an air purifier help with cigarette smoke?
A HEPA filter catches smoke particles and a carbon filter helps with the smell. Neither removes every gas in smoke, so ventilation still matters.
Will it help with pet hair?
It catches pet dander and hair floating in the air. Hair that has already settled on floors and sofas still needs the vacuum.
How often should I change the filter?
Follow the maker's guide, check the filter regularly and replace it sooner if it's visibly dirty.