Don't know who is confusing who here. Not understanding this post - are we talking about particles or gases? You sanded something and measured particulates generated - well yes sanding generates particles. Machine sanding without extract makes those particles airborne. So manual plane and manual sand your timber, or use proper extract for machine use or a decent air fed mask. But if your concern is formaldehyde while you're processing timber then that seems to be a different case. Avoid processed panels, and avoid processes which heat or burn timber unless you have appropriate ventilation or an air fed mask.