May be thinking too hard. I have several thousand flights off the dry lakebeds in California. Lots of dust, dirt and tiny grains to small rocks plus a lot of wind to stir it up. FOD guard catches the big stuff and the rest doesn't do anything except polish the blades and fill up the nooks and cranny's (per John Redman when he worked at Jetcat). Even flown thru dust caused by my own takeoffs and thru blowing sand.

Of course, if you don't use a FOD screen you take your chances. Otherwise, I lost any concern for it years ago. Many of us fly in this environment without any real issues. Plus dozens of guys come out to test fly their jets there.

One of my P-70's did 100 hours without service off the lakebeds and both it and a P-80 are now each over 200 hours. That's over 2,700 flights & 420+ hours between them out in the dirt. They and my other engines have obviously had servicing, but not normally due to the dirt.