I've seen the electrostatic generators as a student but never had a chance to operated one. So I built one. A small one using compact disks. Now I am in the process of building a larger one, using two 12 inch disks cut from acrylic. I've got the completed disks (32 sectors each), base structure, driving mechanism, along with the brushes. I.e. I can create a charge build up on the sectors by driving the disks. Maximal voltage possible is quickly reached given there are no collectors dissipating charge away (say to leyden jars). As compared with my compact disk wimshurst, the scent of ozone is much greater (you would expect). Doing some research, I have found that ozone concentrations over about 0.1 ppm is considered hazardous to be inhaling. At the scale of this machine and considering the various locations of dielectric breakdown, would those levels be easily reached? Surely I can't expect someone to tell me the level of ozone my particular machine generates, but perhaps to some order of magnitude that would indicate a range near or above 0.1 ppm being highly probable or improbable under a usual indoors environment. Iv'e been cranking the disks quite a bit, working in the build to get everything running smoothly and precisely. Before the ozone production hadn't been a concern to me as doing research on these generators and ozone production together has failed to place it's production in the dangerous regions. I actually found just one (unsupported) claim that the levels were too low to cause for concern. But, since about 24 hours ago when I stopped working on the build I have been having some chest tightness and pain. It's a familiar problem I have had with allergies / asthma in the past. It could be that, but the timing indicates otherwise.