Why the class matters here specifically
The International Agency for Research on Cancer classifies wood dust as a Group 1 carcinogen. The fraction that causes the harm is the fine one — small enough to stay airborne for hours after the machine stops, and small enough to reach the deepest part of the lung.
That is precisely the fraction a filter class describes. FFP2 lets through about six times more of it than FFP3, for a couple of euros less per mask.
Checking the seal
Fit the mask, pinch the nose bridge to the shape of your face, and breathe in sharply. The mask should pull against your face. If air comes in at the edge, the class on the box is irrelevant.
Valved or not
A valve lets exhaled air out, which keeps the mask cooler and your glasses clear — and which is why it stays on. It protects you and not the people around you. In a one-person workshop, valved.
When to replace
When breathing through it becomes noticeably harder, or when it stops sealing. A loaded filter is still working; a mask that has lost its seal is not.
This does not replace your machine’s manual. Guards, riving knives and safe working procedures differ between machines, and the manufacturer’s instructions for yours take precedence over anything written here.
What comes up most often
Does a beard stop a mask working?
Yes. A disposable mask seals against skin, and facial hair across the seal breaks it. No filter class compensates for a leak — a powered respirator with a hood is the alternative.
Last reviewed 2026-08-12
