Guys: I just re-read your posts, and, I finally fot the one about the smell. I almost fell off the chair!
In reference to the emitted gasses being sucked directly in, well, mine don't smell bad to me anyway! HA!
As to fit, the unit I bought has a Tyvek headpiece that covers your head, and goes under your chin. There is an acrylic face shield, and that is all. There are no cartridges, and, the pre-filtered air is simply blown into the headpiece. So, there is no fit issue. This was my main reason for switching from the conventional styles-I always found grey trails INSIDE THE MASK that led up my nose. Not good.
Also, my neck is only slightly shorter than a small giraffe's, and, the weight of the respirator combined with always looking down really tires out my back.
I was not really planning to get into this as far as I did, but, now, I think the money will be well spent.
RJ Martin