Came across this article on PetaPixel talking about some hazards with changing lenses outside. Don't let this scare you off from ever changing lenses. Instead be forewarned & prepared when you need to change a lens in this "hostile" environment so you can do it quickly. Have a read...
http://petapixel.com/2015/05/06/be-careful-when-changing-lenses-outside-...
That was a buggy article. :)