All fair points, but I think some perspective is in order. There is dust everywhere all the time, especially in the summer on nice days.
Anybody who does oil analysis will see a certain amount of silicon in the data. This is ingested soil. It is generally accepted that this plays a part in the rate of piston engine wear, but this needs to be seen against an assumed engine life of 2000hrs (which for most private owners is more than 20 years) during which time the engine has ingested a huge amount of soil.
That's why one has an air filter, and the filter should fit correctly.
There is also a tendency among some high altitude GA pilots to fly with the alternate air open all the time (when at altitude). I never do this - not least because it allows ice to form on the front of the air filter and then when you close the alternate air, the engine stops
