I used my half-face mask with the HEPA filter on it on Saturday, a week ago, for part of my ride. I climbed hills on my heavy recumbant, and had no problem with breathing through it. The way I have it configured, there is no activated charcoal, although I do have some alternate cartridges that I will use. When I finished the ride, it only took about a minute to rinse it out, wipe it down (without the cartridges), and hang it up to dry.

One thing to be aware of is that the water vapor in our breath will fairly quickly de-activate the activated charcoal in a mask without cartridges (or without the non-return valves in the respirator). This is one reason I think that the Respro, while pretty good at filtering, will not absorb chemicals for too long.

John