I took my E-M5 with the 12-50 to the desert for a week. We had a little rain, moderate heat and quite some dust (including dust storms). I carried the camera on a backpack strap with a Peak Design Capture clip, never had it inside a bag. Here's what it looked like 900 shots later. So far, I can't tell that it suffered at all. I wiped it down with a damp cloth afterwards. When I removed the lens, there was no visible dust on the inside and behind the battery and memory card doors, you can see how the dust stops right at the gaskets. In case someone is wondering how good dust sealing is in practice.