Researchers from the Australia's Queensland University of Technology looked into 62 brands of printers and found that the particles emitted from some laser printers were a significant health threat, comparable with emissions from cigarette smoking, the study said.

Not all printers were as harmful, though. Thirty-seven of the 62 printers tested did not release enough particles to reduce air quality. Six released low levels of particles and two released medium levels. HP dominated both the list of high-level emitting and non-emitting printers, to which the company responded:

"HP is currently reviewing the Queensland University of Technology research on particle emission characteristics of office printers. Vigorous tests under standardized operating conditions are an integral part of HP's research and development and its strict quality control procedures."
The report also notes that printers release more dust when the toner cartridge is new and when they are required to produce labor-intensive printing projects such as graphics and photos. Scientists concluded that more study and definitive proof is required before establishing any theories regarding the harmful effects of laser printers.