Ozone was formed during the photocopying process. Ozone is produced by the operation of high voltage equipment such as photocopiers, x-ray equipment and electric arc welding. When photocopying, the majority of ozone is produced during the charging and discharging of the drum and paper — it is the breakdown product of the drum material during image transfer. Ozone is also produced by ultraviolet emission from the photocopier lamp.

As ozone usually rapidly decomposes back to oxygen, the normal concentration of ozone around photocopiers is not sufficient to cause symptoms. The rate of decomposition is dependent on time, temperature (the gas breaks down more rapidly at high temperatures) and contact with various surfaces. However, ozone concentration can build up if the room has insufficient ventilation. If ozone concentration reaches 0.25 ppm or above, this odorous gas can cause irritation to the eyes, the upper respiratory tract, and the lungs, throat and nasal passages. Other symptoms include headache, shortness of breath, dizziness, general fatigue and temporary loss of olfactory sensation.