I realise that this is old news but my personal experience tells me that the dusting is a widespread 200 Series problem.
I bought my 200 with 125k on the clock and from what I can tell by the body condition and spending considerable time underneath and under the bonnet etc it has seen very little off road action during it's life. It has been regularly serviced if the logbook is correct and runs like a clock. I removed the intake hose from the airbox and inspected everything when I first bought the car as I was aware of dusting reports on 200's. The air box, MAF sensor and intake tubes were spotless and have remained that way.
My wife and I planned a couple of weeks away with the van so I gave the car a service and changed all filters prior to our trip. I used genuine parts which were actually cheaper (surprise, surprise!).
We spent over a week in the State forests around Tumbarumba and explored quite a few different tracks in the area. We probably did about 200 to 300 k's on dirt in total and wouldn't have passed any more than half a dozen vehicles during that time. I fitted a Safari Armax to the car when I first bought it, so it wasn't drawing air from under the guard and the traffic we encountered was all oncoming so dust shouldn't have been an issue.
When I got home I gave the car a clean and checked the air filter. I was disappointed to see that there was dust on the engine side of the element. Fortunately there was no sign of dust in the outlet tube, it appeared to be only a tiny amount on the top side of the housing.
I know there was no issue with dust prior to our trip and the element was fitted correctly. What this told me was that the factory air-box is not satisfactory and that eventually they will let you down.
I have since purchased and fitted a Donaldson Powercore. They're not cheap but neither is a replacement engine.
