Today, I rode home wearing my half-face respirator. I used a North respirator with a N-100 HEPA filter on it (two cartridges). It was not difficult at all. There was a bit more breathing resistance, but not that much more. I did notice several things. I stopped to turn on a light in my work parking lot, and one of my workmates stopped his car to see whether I needed help. But it was very difficult to talk with him. It's well known that communications is inhibited by a respirator, and this simply confirmed it. Also, I noticed that even in the cold air, my safety glasses did not fog up. That's because the exhalation valve is below my chin, and so no warm, moist air from my breath got to the glasses. Finally, I did not smell the car exhausts. All in all, I will be using the respirator again.

A couple of other points:

--Respirators need attention. They cannot just be used over and over again. The filters need changing once they become clogged (or for those with activated charcoal, when gases are smelled through them). The mask needs to be cleaned after each use to prevent the development of bmacterial buildup inside it.

--Fit testing for the general public is not necessary, but is highly desireable (it's the law for workers). You can test the fit of the half-face non-disposable cartridge respirators by covering the filters, and breathing in. If the respirator collapses onto your face, the fit is good. If air leaks around the seals, it is not. Then blow out while plugging the exhaust valve. It should inflate slightly before air leaks around the seals. This is a test that workers must perform each time they put on a respirator, even after they have been fit tested.

--If you have asthma, clausterphobia, or any other thing that could affect wearing a respirator, get a respirator physical first. Tell the doc why you want to wear one, and bring it with you (many who do respirator physicals can do the fit testing). Since there is increased breathing resistance, and you are bicycling, be very careful here. If you even have the question, get a physical.

John