All that CAN be done to mitigate risk SHOULD be done (mental and physical health/state, gear, street experience, riders class, trackdays), but the only way to eliminate it entirely is to not ride.....and that simply isn't an option, at least for me. The question is simply, what level of risk are you willing to and SHOULD you take? If the road is more hazardous/dirty and/or you're not feeling right, dial it down. The more experience you have the better you are at determining those factors and how much you should slow. It's far better to ride slower at 40% of your max pace than slightly faster at 80% of your max pace.

For instance, I'm feeling pretty sick now with a bad sinus infection/cold, and I'm not even feeling up to riding from a strength/balance/fatigue standpoint right now. IF I make it out this weekend, it'll be for a very mild putt around town or MAYBE in the mtn's, but I'll have it dialed way back because I don't feel right (dizzy/weak).