I used to sit next to a big laser printer. Then, one of the editors I work with sent around an e-mail with some scientific references that made us, and the rest of the company's employees, sit up and take notice. You should as well if your company is naive enough to put a printer next to you.

If you are a company executive, you should immediately move any printer away from your staff after reading this. I do not mean to be alarmist, but here are the results of the study that sparked off the concerns.

A scientific study published in the August 1, 2007 online issue of the American Chemical Society's Environmental Science & Technology journal found that certain laser printers release tiny particles of toner-like material into the air. People can then inhale those particles into lungs where they may pose a health hazard, the scientists report.

Toner is the ultrafine powder used in laser printers instead of ink to form text and images. The study by scientists at Queensland University of Technology in Brisbane, Australia, classified 17 out of 62 printers they looked at as "high particle emitters" because they released elevated quantities of particles they believe to be toner.

Thirty-seven of the 62 printers released no particles that diminished air quality, six released only low levels, and two emitted medium levels, they found. One of the printers released particles into an experimental chamber at a rate comparable to the particle emissions from cigarette smoking.

Most of the printer-generated particles detected were classified as ultrafine contaminants that are easily inhaled into the smallest passageways of the lungs where they could pose "a significant health threat", reported Lidia Morawska, the lead scientist for the study.

The study found that indoor particle levels in the office air increased five-fold during work hours due to printer use. Printers emitted more particles when operating with new toner cartridges, and when printing graphics and images that require greater quantities of toner.

They tested all of the printers in an open office. Three of them were also tested in the experimental chamber. The health effects from inhaled ultrafine particles depend on particle composition, but the results can range from respiratory irritation to more severe illnesses, such as cardiovascular problems or cancer, the study reported.

"Even very small concentrations can be related to health hazards," Morawska said. "Where the concentrations are significantly elevated means there is potentially a considerable hazard."

Under their scrutiny were popular office and home models sold in the US, Australia and internationally under the Canon, HP Colour Laserjet, Ricoh and Toshiba brand names. Actually the emphasis was on HP printers.

For the record the high particle emitters of the printers in the study were: HP Colour LaserJet's 4650dn, 5550dtn, and 8550N; the HP LaserJet 1320N, 1320n, 2420dn, 4200dtna, 4250n, 4250n, 5, 8000DNa, and 8150N; and the Toshiba Studio 450.

Morawska recommended that people make sure rooms at work and home with laser printers are well ventilated. The scientists are also calling on governments to impose limits on the emissions from printers. As a first step to lower risk, rooms in offices or houses should be well ventilated to allow airborne particles to disperse.

I have checked HP's online newsroom but the company does not seem to have issued an official response there. However PC World contacted the company and HP told them in a statement that it is "reviewing" the Queensland University study and that as part of its quality controls HP print cartridges and papers are "checked for dust release and possible material emissions to ensure compliance with applicable international health and safety requirements".

On the positive side, remember that 37 printers, most of them made by HP, were found to emit no particles. Go to the study and look at the list if you are in the process of buying a printer. You can find the study here: http://pubs.acs.org/cgi-bin/sample.cgi/esthag/2007/41/i17/html/es063049z.html.

This is not the first time warnings have been issued about the health hazards of printers. A 2002 fact sheet by the London Hazards Centre reports that poorly maintained photocopiers and printers in badly ventilated areas "may" pose a risk to health, ranging from irritated eyes, nose and throat to dermatitis, headaches, premature ageing and reproductive and cancer hazards.

The health risks are due to the volatile organic compounds and ozone emitted by poorly serviced equipment.

"Photocopiers and laser printers are safe when used occasionally and serviced regularly," the study states, adding that: "Proper ventilation and maintenance are essential in eliminating hazards."

But before you get too alarmed just note that the Australian study noted that the high standard deviation of the average emission rates of the printers they examined indicates that the particle emission process and the behavior of individual printers are complex and "that they are still far from being completely understood".

Many factors, such as printer model, printer age, cartridge model, and cartridge age may affect the particle emission process and all of these factors require further study.

Even though the printer I was sitting next to was on the good side of the list in the Australian study, it now sits in the hallway.

Now people are complaining about having to walk too far to get their printouts.

If you have any comments send them to Ahmed at elamin.ahmed@gmail.com