Physical Danger
The risk of physical danger isn't high, but it sort of depends on where you give tours. If you're giving tours on the architecture of Catania, Sicily, where it's illegal for motorists to drive at any speed lower than a billion miles per hour (or so it would seem), you're probably going to want to stick to giving indoor tours.
If you're doing something like a Grand Canyon walkabout or other intense escort service, you're definitely looking at an upgrade on the danger. On the other hand, if you're talking your way through the Mark Twain Boyhood Home and Museum in Hannibal, Missouri? We expect you'll come out of that one unscathed.