Very fine wood dust can be inhaled into the lungs. There, particles can linger and cause breathing problems, allergic reactions, and decreased lung capacity. Wood dust is a known carcinogen, which can be a serious problem during long-term occupational exposure.
In wood shops, even high-end dust collection systems mostly capture the larger wood particles (the ones that don't cause health impacts). Smaller particles will hang in the air (or land, but then later be kicked up when disturbed). The best way to remove these is with an air filtration system. [1]
See https://en.wikipedia.org/wiki/Particulate_matter#Size,_shape,_and_solubility_matter
| Particle diameter | Name | Anatomy | Disorders | Notes |
|---|---|---|---|---|
| 2.5 - 10 μm | PM10 Coarse particles | Can deposit in the upper airways, including the nose, throat, and bronchi. | [1] | [source] |
| 0.1 - 2.5 μm | PM2.5 Fine particles | Can penetrate deep into the lungs, reaching the bronchioles and alveoli. | [1] [2] [3] | |
| < 0.1 μm | PM0.1 Ultrafine particles | Can traverse the alveoli's cell lining and enter the blood stream. | Not a concern with wood dust, but can be an issue with silica. |