That is why I'm pulling intake air from inside. I taped off most of the combustion air grill to help keep that salty air out. On the munchkins I would get bad pitting inside the aluminum blower motor if the location was near the ocean.
That is biggest concern. I have around 15 of the ufts installed. The ones I've been back to all have a little dust in the intake air pipe. I've serviced hundreds of munchkin. With the dirtiest ones being low temp and running on LP.