Nearly all the laser printers fingered by researchers for spewing particulate matter into offices and homes are sold by Hewlett-Packard, a study published Wednesday said.

The report , which appeared in the American Chemical Society's Environmental Science & Technology (ES&T) journal, measured emissions of 58 laser printers, including models from Canon, HP, Ricoh and Toshiba. Particle emissions, believed to be related to the ultrafine powdered toner, were measured and the printers ranked in several categories.

Of the 13 printers described by researchers as "high emitters," 12 were made by HP, including the Color LaserJet 4650dn; Color LaserJet 5550dtn; Color LaserJet 8550n; LaserJet 1320n; LaserJet 2420n; LaserJet 4200dtn; LaserJet 4250n; LaserJet 5; LaserJet 8000dn; and the LaserJet 8150n.

HP printers also made up the majority of those tested. Of the 58 printers researched, 48 -- or 83% of the total -- were from were HP.

Of the 37 in the "non-emitter" category, 29 were made by HP, as were five of the six "low emitter" printers and both "middle level emitter" models. In total, HP's printers accounted for 19 of the 21 devices that emitted measurable rates of particulates, or about 90%.

When reached for comment, an HP spokeswoman said that the company's engineers and R&D staff are reviewing the research paper, and would not have a detailed response until tomorrow. "HP is currently reviewing the Queensland University of Technology research on particle emission characteristics of office printers," she said. She also said that as part of its existing testing, HP regularly assesses laser printers, HP-branded toner cartridges and paper for "dust release and possible material emissions" to comply with necessary health and safety regulations.

The three co-authors of the paper -- who are either from Queensland University of Technology in Brisbane, or with the Queensland Department of Public Works -- also ran additional tests on selected printers, and found that emissions may also be tied to the age of the toner cartridge.

New cartridges in the HP 1320n, for example -- one of the "high emitters" -- averaged higher emission rates than when did partially-used cartridges in the same printer. Even though the researchers said statistical analysis of the data showed that the differences were not significant, they pointed to toner age as a possible contributor to higher particulate rates and called for further study.

"While a more comprehensive study is still required to provide a better database of printer emission rates," they wrote in the paper, "the results imply that submicrometer particle concentration levels in an office can be reduced by a proper choice of the printers."