Australian researchers have traced the origin of harmful particles in the laser printer dust. These tiny particles are potentially dangerous to human health because they can penetrate deep into the lungs.
Almost one third of popular laser printers emitted large numbers of such ultrafine particles, it is believed.
A Queensland University of Technology team has found that those particles are formed from vapours produced when the printed image is fused to the paper.
"In the printing process, toner is melted and when it is hot, certain compounds evaporate and those vapours then nucleate or condense in the air, forming ultrafine particles," said Professor Lidia Morawska from QUT's International Laboratory for Air Quality. She had led the study.
"The material is the result of the condensation of organic compounds which originate from both the paper and hot toner," Morawska said.
The study compared a high-emitting printer with a low-emitting printer and found that there were two ways in which printers contributed to the formation of these particles.
"The hotter the printer gets, the higher the likelihood of these particles forming, but the rate of change of the temperature also contributes," Professor Morawska said.
"The high emitting printer operated at a lower average temperature, but had rapid changes in temperature, which resulted in more condensable vapour being emitted from the printer.
"The printer with better temperature control emited fewer particles."
Professor Morawska said this research provided information which would help consumers better understand the risks of laser printers and would help the printer industry to design low or no emission printers.