Lidia Morawska and Congrong He at the Queensland University of Technology and Len Taplin at the Queensland Department of Public Works, both in Brisbane, investigated the submicrometer particle emissions produced by each of 62 printers (from Canon, HP and Toshiba) used in office buildings and, based on the particle concentrations in the immediate vicinity of the printers, after a short printing job, the printers were divided into four classes: non-emitters, and low, medium, and high emitters. It was found that approximately 60% of the investigated printers did not emit submicrometer particles and of the 40% that did emit particles, 27% were high particle emitters.
While a more comprehensive study is still required, to provide a better database of printer emission rates, as well as their chemical characteristics, the results from this study imply that submicrometer particle concentration levels in an office can be reduced by a proper choice of the printers.
Morawska says they did not investigate the chemical composition of the particles, but plan follow-up studies. She suspects toner is directly released into the air rather than producing secondary particles.
Of course there is a lot of research on the connection between ultrafine particles (UFP) in the air and health implications. Morawska and He were careful not to jump to such conclusions but rather just report on the contribution of office printers to an increase in UFP found in office air. Further studies are needed to determine what the implications of this are. Nevertheless, it might be a wise move to err on the side of caution and use laser printers that do not emit UFPs.