On this episode of "When Laser Printers Attack," it turns out your laser printer is not guilty of releasing noxious particles into the air, as previously reported by this Australian health alert (PDF) last year. The report claimed that some laser printers sporadically spew certain "toner-like" particles that pose the same amount of health hazard as cigarettes. As it turns out, laser printers hardly release any of these noxious chemicals into the air and it's perfectly safe to use one without wearing a Hazmat suit.
The good scientists at the Fraunhofer-Gesellschaft applied research institute just released this research study that empirically refutes the argument made by the Australians. It states that that "contrary to numerous reports, laser printers release hardly any particles of toner into the air."
The particles are actually made of volatile organic-chemical substances, or VOCs, and while they do confirm that they exist, the VOCs aren't nearly as deadly as a cigarette; in fact, the accused printer perpetrators emit the same level of VOCs as the common toaster, and nobody's keeling over trying to make toast in the morning, so it's safe to assume that your printer is probably not going to be your cause of death. The article goes on to dispel the myth of VOC filters: "As the ultra-fine particles are not emitted from a specific part of the printer, but also from the paper output, for instance, a filter can only have a limited effect."
Lesson learned: use your laser printer with peace of mind; don't lick the toner cartridge; and take solace knowing that everything around us emits some form of small particle/gas/radiation/carcinogen, but only a handful of it is toxic. I think.