What carbon does (and doesn't) do
Activated carbon adsorbs gas molecules — cooking smells, smoke odour, VOCs from paint and furniture, pet and bathroom odours. It does not capture fine particles, so carbon is always used alongside a particle filter, never instead of one.
When you need carbon
- Cooking, frying or persistent kitchen smells.
- Tobacco, wildfire or bonfire smoke odour (the smell, after the particles are filtered).
- New furniture, flooring or paint off-gassing (VOCs).
- Pet or damp/musty odours.
If your only concern is pollen or dust, you may not need carbon at all — a particle filter is enough.
How often to replace carbon
Carbon saturates faster than particle media — typically 3–6 months depending on odour load. Once it's full it stops adsorbing (and can even release stored odours), so it needs its own schedule. Carbon weight matters: a thin carbon-coated mesh does little; meaningful odour control needs a proper carbon bed measured in hundreds of grams.