To follow up on this, I got one of these zipper masks: My first concern was how covered the zipper would be, but the backing fabric completely covers the zipper. It unzips relatively easily, but rezipping requires both hands. That's OK if I'm stopping to yield the trail, but less OK if I would be able to roll past.I've created a couple of masks that hook to my helmet straps for easy cover/uncover while riding. In the lower foothills single track I just keep it on because I know that I will see people, but once I get farther up I go 15-45 minutes without seeing another person so its just hanging from my helmet. This mask with a zipper might be an option...zip it for snot blocking, unzip it for more free breathing.