Ozone and Other Air Pollutants from Photocopying Machines

Abstract

The ozone emission from 69 different photocopying machines was determined by a described standard procedure. The emission rates were in the range of 0 to 1350 µg/min with mean 259 and SD 302. The standard procedure need not be carried out in a special test-chamber, but can be carried out in nearly any office where the photocopier is placed. When placing a photocopier with a given ozone emission rate in a room, one must consider the room size and the air changes in the room in order to minimize the ozone concentration. The maximum ozone concentration in the breathing zone of 19 operators was found to be between <0.001 and 0.15 ppm. Technical conditions for the amount of ozone generated by photocopiers are described, as well as conditions for the rate of decomposition of ozone. Ozone filters can minimize the ozone emission. The efficiencies of three different types of filters were tested. Activated carbon granulate, ranging from 9 to 14 mm, decomposes 89% to 98% of the ozone, depending on the thickness of the filter, the air velocity through the filter, the initial ozone concentration and the degree of pollution on the filter. Polyester and polyurethane impregnated with activated carbon, ranging from 8 to 12 mm, decompose 5% to 72% of the ozone, depending on the same factors as previously mentioned. Other pollutants from the copying process have been reported to be cadmium, selenium and arsenic, at concentrations of 0.01 to 0.6 µg/m3 for selenium and arsenic and 0.2 µg/m3 for cadmium. In our own measurements, the concentrations for selenium and cadmium were less than our limit of detection, 0.004 and 0.6 µg/m3, respectively. Dust concentrations (toner) in the air exhausted from photocopiers were found in the same magnitude as normal dust concentrations in offices (0.05 to 0.5 mg/m3). Vapors from the resin in the toner were often present in concentrations and gave operators an unpleasant feeling; however, further investigations still have to be carried out concerning the health hazards from these vapors and from the possible reaction products between the vapors and ozone.