I blow stuff up for a living (EOD), and I spend a lot of time outside on a demolition range. Dirt, snow, sand, and even mud are always there. I don't worry about my Aegis at all. I usually leave it on the ground at our control point, and it's been knocked over, and even accidentally kicked once. Still works like the day I bought it.
I also bought a silicone sleeve for it from ModShieldz by JoJo. It fits perfectly and looks good!
I washed my mod under running water the other day- no issues.