Objective To investigate the levels of indoor air pollutants, including particles, ozone, and total volatile organic compounds (TVOC), released from laser printers and the attenuation patterns of the pollutants over time during printing process in workplaces.
Methods Particles, ozone, and TVOC produced during printing process by three selected brands of laser printers were detected by ultrafine particle counter, ozone monitor, and VOC monitor, respectively. The distribution of particle size was also described with nanoparticle sizer at the same time.
Results The selected laser printers produced a higher concentration of particles during printing process (34 783 particles/m3) than the indoor background concentration (6 843 particles/m3). Both the average concentrations of ozone (0.38 mg/m3) and TVOC (2.38 mg/m3) exceeded the threshold values (ozone:0.16 mg/m3; TVOC:0.60 mg/m3) stipulated by the national Indoor air quality standard (GB/T 18883-2002). Ultrafine particles with a size range of 10-238 nm composed the majority of particles released from the printers, of which the particles size less than 49 nm and less than 116 nm accounted for more than 37% and 92% of the total particles, respectively. In addition, the concentrations of particles and ozone returned to the level of environmental background 2-3 min after the end of printing. The attenuation of TVOC was slower and its concentration remained at a high level after 10 min following the end of printing (0.14-0.19 mg/m3).
Conclusion The sizes of particles produced by selected laser printers are mainly under 116 nm. Along with increasing printing workloads, all the concentrations of particles, ozone, and TVOC are increased. The concentrations of particles and ozone attenuate quickly, but the concentration of TVOC attenuates slowly and has a long-time adverse effect on indoor air quality.
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