Australian researchers have found that laser printers might pose a health threat because of tiny airborne toner-like particles that they emit.

Spurred by the study's findings, the scientists are calling on government officials to consider regulating emission levels from laser printers.

The researchers examined 62 printers and found that 17 released elevated quantities of particles, which the researchers believe to be toner, the ultra-fine powder used in laser printers, instead of ink, to form text and images.

On the other hand, 37 of the 62 printers released no particles that diminished air quality. Six released only low levels, and two medium levels.

The study, led by Professor Lidia Morawska from Queensland University of Technology in Brisbane, is set for release in the Aug. 1 online issue of the American Chemical Society's Environmental Science & Technology.

All printers were monitored in an open office, and the researchers recorded data on three laser printers in an experimental chamber.

"One of the printers released particles into an experimental chamber at a rate comparable to the particle emissions from cigarette smoking," said the report.

The study found that indoor particle levels in the office air increased fivefold during work hours due to printer use. Printers emitted more particles when operating with new toner cartridges, and when printing graphics and images that required greater quantities of toner.

The study included various makes of printers such as Canon, HP Color Laserjet, Ricoh and Toshiba, of which some are reported to be sold in Canada.

A Hewlett-Packard Canada spokesperson told CBC News that the company is currently reviewing the study, and added, "Vigorous tests under standardized operating conditions are an integral part of HP's research and development and its strict quality control procedures."

"HP laser printing systems, original HP print cartridges and papers are assessed for dust release and possible material emissions. HP follows international health and safety requirements and considers scientifically recognized assessment and certification criteria," said HP.

"In the working environment there also have been associations of adverse health effects with certain particulate exposures such as from welding fumes, and diesel exhaust fumes [mostly causing respiratory effects]," Dr. Susan Tarlo, a specialist in respiratory illnesses at Toronto Western Hospital, told CBC News.

"Again, it is not completely clear as to how much this is due to particular chemical components rather than to a less specific effect of the particles."

"At present it is not possible to generalize from findings in air pollution studies to assume adverse effects from all fine particle exposures under different conditions," she added.

"By all means, this is an important indoor source of pollution. There should be regulations," said Morawska.