I have been using the So Clean for just over 4 years. I own two homes and I bought one for each. I have only experienced the Ozone smell on the first few days of a new machinine, much like “new car” smell (not the smell , the temporary effect), and even if it was permanent it wouldn’t bother me. I use the machine every day, my wife puts the mask in the machine when she makes the bed. I do still have to clean the water tank sometimes, there is the same calcium buildup that it got before the So Clean. The clip that holds down the lid is ridiculously fragile, but when my original machine broke, I just started putting a weight on the lid when it was closed, and that works at least as well as the clip. I used to wash my equipment now and then, but I always knew there would be a better way. This is it. the biggest negative is the cost, and the fact that it is not covered by insurance.