Workers face a potential health threat from office laser printers that emit large amounts of tiny particles into the air, an Australian research team has found.

Potential effects range from respiratory irritation to effects on the cardiovascular system and cancer, says author Professor Lidia Morawska from the Queensland University of Technology.

The researchers do not know the chemical makeup of the particles and how they are released. But they recommend good office ventilation to minimise the chances of particles entering the airways.

Morawska and colleagues will publish their results online later this week in the American Chemical Society journal Environmental Science & Technology.

The researchers classified 17 of the 62 printers as "high particle emitters".

And Morawska says one printer released particles, under experimental conditions, at a rate comparable to the particle emissions from cigarette smoking.

But 37 of the printers were non-emitters.

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.

Morawska, who is the director of the International Laboratory for Air Quality and Health, says when inhaled the ultrafine particles can travel to the deepest parts of the respiratory tract and then enter the bloodstream.

The potential health problems range from increased respiratory irritation to effects on the cardiovascular system and cancer, she says.

Morawska says the findings were made by chance while her team was investigating the efficiency of ventilation in protecting office workers from outdoor pollution.

The researchers tested a large open-plan office in the Brisbane central business district, surrounded by busy roads and about 120 metres from a freeway.

"We really didn't expect to find anything from indoor sources [but] we soon discovered that the indoor sources of pollution were far higher than the outdoor sources," she says.

Discovered

The study shows average particle number concentration inside the test office is five times higher during working hours than non-working hours.

And at its highest levels, indoor particle concentration was about three times higher than the outdoor rate.

Morawska says in offices with poor ventilation higher concentrations of particles can "prevail for the whole day".

She says the health risks will be "quite high" for workers that "sit in an office like this for days and months".

Regulation

Her research team is calling on governments to consider regulating emission levels from laser printers.

But Morawska says more research is needed into the chemical makeup of the emissions and how the particles are released to back any such move.

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 says until governments move to regulate printer emissions, office managers should consider buying printers that are classified as low emitters.

Most important however, she says, is to locate the printer "where the air flow doesn't distribute the particles to the whole office".

The National Industrial Chemicals Notification and Assessment Scheme and Hewlett Packard were unable to comment in time for the story.