Cancer from ozone is probably like #3846 on the list of things that can kill you. The #1 non-disease risk is drug overdoses, followed by suicide, then your car, followed by falls from stairs/ladders. If you're worried about your health and safety, worry about those instead. A little effort to improve your driving skills will yield a much greater reduction in your risk of death than a lot of effort to eliminate emissions from your computer.
Ozone is produced by injecting high energy into atmospheric oxygen to convert it from O2 into O3. If you think of the energy gradient as a hill, you need to push the O2 up the hill far enough to where it'll form O3. That takes a lot of energy concentrated in a very small space (so it affects individual O2 atoms). A processor running at 90C (not even hot enough to boil water) will not create it. Aside from an arcing PSU, the only other component I can think of that could are the voltage converters on the old CFL backlights. Those had to bump up the computer's 12V to several thousand volts to drive the fluorescent bulb.