# PM1.0, 2.5 and 10 laser test values 1-5 ug/m3 but dust visible under sunlight. Does it make sense?

I wonder if household dust is visible and/or harmful. At home, it is visible under sunlight and it is small pieces the size of human hair or slightly smaller. The density by looking at it is substantial to the point that I think I breathe it in any given breath.

I measured using my laser tester for pm1.0, 2.5 and 10 and it measured low values. 1-5 $$\sf\mu$$g/m3. Even the analytical view showed e.g., 450 particles > 0.3 $$\sf\mu$$g, 50 > 0.5 $$\sf\mu$$g (obviously some of these are not visible to the naked eye). I just cannot tell if the measuring device is broken or if dust is much larger than pm10 and thus not harmful (probably blocked by our nostrils etc.)

Does anyone know what the typical size of household dust is and if these numbers make sense?