The generation of X rays is always associated with the generation of cathode rays inside the vacuum devices. A sign of possible X-ray generation is fluorescence in the glass walls, associated to absence of light in the vacuum volume. All the usual electrostatic machines produce sparks at the connections through points, at the main terminals, and through corona effects. Ozone is irritant to the upper respiratory tract and eyes, causes headaches, and can be poisonous to plants and animals when in high concentrations. It is also highly reactive, and can damage the machine itself, through oxidation and decomposition.
Ozone has a characteristic smell, often felt during thunderstorms.
The construction of the machines shown in this site requires some hability with tools, and this hability is the insurance against accidents. Be careful and patient, use adequate protection, and ask more experienced persons for assistance when necessary. Be careful to not deform plastic parts with the heat. Blowing the disks from above, while turning them, is the most effective method. Insulators must be very good.