The laser printer on that desk near you could be making you sick.

Almost one-third of popular laser printers emit large numbers of ultra-fine particles that could lead to cardiovascular problems, Australian researchers found.

Professor Lidia Morawska, of Queensland University of Technology's International Laboratory for Air Quality and Health, found tiny harmful particles were formed when toner was fused to the paper.

Morawska, who led the study, said these particles, which were about the same size as smoke and vehicle-emission particles, were potentially dangerous.

"These particles deposit very deeply in the human respiratory system and can cause irritation," she said.

"It depends on the concentrations."

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