What a HEPA purifier removes
A true HEPA filter is tested to capture at least 99.97% of particles at 0.3 microns, the size that is hardest to trap.
- Fine particles from smog and smoke (PM2.5).
- Dust and dust mite debris.
- Pollen and pet dander.
- Mould spores.
The benefits
- Cleaner air in the room where you sleep or work, especially in smog season.
- Fewer airborne allergy triggers such as pollen, dust and dander.
- Less dust settling on furniture.
- For people with asthma or allergies, fewer airborne triggers can help. A purifier supports, but does not replace, the treatment your doctor recommends.
What a purifier cannot do
- It cannot clean the air of a whole house from one room, or a room with open doors and windows.
- A particle filter alone does not remove gases and odours. That needs an activated carbon stage.
- It does not bring in fresh air, so it does not lower CO2 in a closed room. A fresh air unit does.
- Ozone generators and ionizers that produce ozone are not a substitute for HEPA filtration.
Air purifier and humidifier in one?
Combined units add moisture as well as filtering. That can help in very dry winter air, but the water tank needs regular cleaning to avoid mould. If your main problem is smog or dust, choose on HEPA performance and room size first.
Do you need one?
- You live in a city with winter smog.
- Someone at home has allergies or asthma.
- You live near a busy road, construction or other dust sources.
- You run an office, clinic or classroom with many people in closed rooms.
Frequently asked questions
Do air purifiers help with smog?
Yes, indoors. A true HEPA purifier sized for the room removes most PM2.5 from that room's air while doors and windows are closed.
Can an air purifier help with asthma?
It can reduce airborne triggers such as dust, pollen and smog particles in the room. It supports treatment but is not a replacement for medical advice.
Should I run an air purifier all day?
In smog season, yes, in the room you use most. Purifiers work best running continuously with the room closed.
