Workers could face a health threat -- in some cases, on par to that of cigarette smoking -- from office laser printers that emit large amounts of tiny particles into the air. Potential effects range from respiratory irritation to effects on the cardiovascular system and cancer, said Professor Lidia Morawska from the Queensland University of Technology, as reported in Australia's ABC Science Online. Morawska, director of the International Laboratory for Air Quality and Health, said the ultrafine particles, when inhaled, can travel to the deepest parts of the respiratory tract and then enter the bloodstream. The researchers do not know the chemical makeup of the particles and how they are released, but they recommend good office ventilation to minimize chances of particles entering the airways. The researchers classified 17 of the 62 printers they tested as "high particle emitters." Under experimental conditions, one printer released particles at a rate comparable to the particle emissions from cigarette smoking, Morowska said, but 37 of the printers were nonemitters, according to the news report. The study found printers emitted more particles when the toner cartridge was new and when printing images and graphics, as these require greater amounts of toner, it said. Morawska and her colleagues will publish their results online later this week in the American Chemical Society journal Environmental Science & Technology. The findings were reportedly made by chance while Morawska's team was investigating the efficiency of ventilation in protecting office workers from outdoor pollution. They tested a large open-plan office in the Brisbane central business district, surrounded by busy roads and about 120 meters (.074 miles) from a freeway. Morawska said they didn't expect to find anything from indoor sources but soon discovered that the indoor sources of pollution were far higher than the outdoor ones. Their study showed that average particle number concentration inside the test office is five times higher during working hours than nonworking hours. At its highest levels, indoor particle concentration was about three times higher than the outdoor rate. In offices with poor ventilation, higher concentrations of particles can "prevail for the whole day" and the health risks will be "quite high" for workers who spend long periods in the office, according to the news report. The research team is calling on governments to consider regulating emission levels from laser printers. But Morawska said more research is first needed into the chemical makeup of the emissions and how the particles are released. Her paper includes a list of the brands and models studied and their rating by amount of particles emitted. A total of 12 models of Hewlett Packard printers and one Toshiba printer are listed as high emitters of tiny particles. Morawska said until governments move to regulate printer emissions, office managers should consider buying printers that are classified as low emitters and to locate printers where the air flow doesn't distribute the particles to the entireoffice.For more information, visit: www.qut.edu.au