ORIGINAL: Sport_Pilot
Dust is normally a ''soft'' particulate that deforms under pressure. e.g. it is mostly organic.
The dust off your asphalt or concrete or grass strip is mostly clay or sand. Much worse than a few particles of aluminum.
Metal particles on the other hand will do things like score cylinders and rings.
I thought this was microscopic metal, so the scoring is also microscopic. Dust is much larger than microscopic.
Not too long ago there was an article in one of the RC magazines that talked about the damage done to engines by the bits of burned out glow plug wire that make their way into the crankcase on engines...
A burned out glow plug is a lot larger and harder than a few flecks of microscopic aluminum.
Having overhauled a few engines where damage was done by metal particles
We are not talking about macro metal particles here, this is micro particles.