Tesla Coils - Is there a risk that the discharge can create x-rays? I've built a Tesla coil that stands about 3 ft tall and uses a spark gap as the interrupter for the primary circuit. Judging by the size of the streamers it's reaching at least a million volts.
Someone once told me that you have to be careful with Tesla coils because they can create x-rays. I had been skeptical, but then read about how x-rays can be produced by unwinding scotch tape. So now I am somewhat concerned.
So are harmful x-rays a risk with Tesla Coil operation, and if so how can I easily test my system to see if it's safe?
 A: Generally Tesla coild are fairly safe from the point of view of X-ray generation. You could potentially test for it using a sealed can of camera film with a high ISO rating, placing it in the vicinity of the coil while it is operating, and then developing it to see if it is fogged.
However, a bigger problem might be ultraviolet light, ozone and nitrogen oxides produced by the discharge. None are good for your health, but you can smell the latter. An article on safety here
A: I defer to:
https://webhome.phy.duke.edu/~rgb/Class/safety.html
They do list X-ray generation, however the primary risks are ozone (which destroys organic compounds; your body is primarily composed of organic compounds...) with insufficient ventilation and electric shock.
X-rays are typically generated using 20kV to 60kV.  A Tesla coil can definitely reach that range of voltage.
They will also fry electronics, including pacemakers.
A: Put a cover in front of the spark gap to shield your eyes from direct exposure to the UV light it produces. The risk is similar to arc-welding. You don't want to stare at the spark gap while it's running. The more powerful the Tesla coil the greater the risk. Run the coil for short periods of time somewhere well ventilated; that's the only way to deal with the Ozone.
