Last post I mentioned I cut some ABS sheeting for a friend's project. As Angie Brennan pointed out to me on Saw Mill Creek's forums, this probably isn't the most healthy idea in the world. According to the ATX Hacker Space website, which has a very nice chart of what you should and shouldn't cut on their laser, the ABS "Emits cyanide gas and tends to melt." While I disagree that it doesn't cut well, at least in thin sheet form, it's probably best to heed the warning about cyanide gas. My laser is well ventilated and the negative pressure setup should send all bad stuff outside... I have no way of measuring or knowing so I'll be limiting this stuff in a big way. After a long search on Google my conclusion is this:
Pretty much everything you can cut with a laser will emit something that is NOT good for you to breath. Paper, plastic, acrylic... all of it. So ventilate well, even after the cut so any leaching from hot plastic is minimized, wash your hands, and limit cutting plastics as much as you can.
This is probably a good place to link to the Make page about determining unknown plastics. Better to find out what you are cutting than to breath chlorine or cyanide eh?