That laser printer sitting on your desk could be emitting high levels of potentially hazardous particles, according to a study published today.
Some printers released almost as many ultra-fine particles as a smoldering cigarette, the study authors said.
There have been few studies on the health hazards of printing, and the current research, appearing in the journal Environmental Science and Technology, provides the most extensive look yet at particle emissions of office printers, including Canon, Hewlett-Packard, Ricoh and Toshiba models. The researchers did not analyze what the particles consisted of.
"Particles have been shown beyond any doubt to be a health hazard," said study author Lidia Morawska, a physicist at Queensland University of Technology in Australia.
Inhaling fine particles can cause health problems ranging from respiratory irritation to cardiovascular problems and cancer, depending on the particle composition, Morawska said.
The emissions varied widely among printers. Morawska and her colleagues classified 37 printers as non-emitters, eight as medium or low emitters, and 17 as high emitters.
Among the machines that had no emissions were eight HP LaserJet 4050 series printers and four Ricoh Aficio models.
High emitters included the HP LaserJet 1320 and 4250, which, when printing, increased the particle number in the air more than tenfold.
The study did not consider variables such as printer age or cartridge type, leading to variations even among printers of the same model. The scientists noted that they found one HP LaserJet 5 to be a high emitter, while another was a non-emitter.
Hewlett-Packard, maker of the LaserJet printers, responded that it tests all products for dust emissions and follows international health and safety requirements.
Morawska did not originally set out to study printers. She was invited by the Queensland Department of Public Works to measure air quality inside a six-floor office building near a busy road.
The scientists quickly noticed that during the workday, particle levels were much higher indoors than out. Indoor levels reached as high as 625,986 particles per square inch, compared with 178,619 particles per square inch outside the building.
Printers were clearly the culprit: Copy machines and a break room microwave were not main particle sources.
The researchers then analyzed air quality near each printer after it had printed one page, and used this data to categorize printers by the amount of particles released. Particle levels rose as soon as the printer started.
The scientists then chose three printers -- a low, medium and high emitter -- for further studies inside a closed chamber.
A newer toner cartridge released more particles than an older cartridge, the scientists found. Printers also emitted more particles when printing toner-heavy documents such as graphics.
The study primarily considered particles less than a micrometer in size, but the authors noted that even the printers labeled as non-emitters might be releasing larger particles, which are also potentially hazardous to human health.
Other studies have found printers to emit volatile organic compounds and ozone as well as toner particles.
Morawska recommends that homes and offices have adequate ventilation to ensure that the printer particles are dispersed.