During our recent 2,250 mile jaunt through Colorado, we decided to get adventurous one day, and took a 3-hour drive on a gravel and dirt road scenic route. We kicked up enough dust that it took me all day to clean out all the nooks and crannies after we returned home.
During the clean-up, I removed the (original, factory) air filter (now that's a fun job!), and blew it out from the back with an air compressor. I was amazed at how little dust came out of the thing, especially considering how it's mounted in the engine compartment (up front, facing forward, exposed directly to incoming outside air).
The lower parts of the front bumper and rear fender protectors didn't fare so well, however ... they incurred a few rock chips. But the scenery was worth it!