Laser cutting polyurethane

I have a laser cutting machine and have always read that PVC (or types of vinyl in general) are very dangerous to cut because it releases chlorine gas. Chlorine gas = toxic (plus the $\ce{HCl}$ thing), makes perfect sense. This is well-known information, and it appears all over informational sites about laser cutting materials.

But I now have someone telling me that cutting polyurethane foam is way more dangerous since it produces $\ce{HCN}$ (hydrogen cyanide). Now this information is in a few limited places and mentioned kinda as a footnote, but it is not nearly as widespread as the Chlorine gas risk that is talked about elsewhere. (I know that the chlorine gas presence during cutting of PVC effectively makes $\ce{HCl}$ gas which clearly does damage to the laser system itself which might explain the prevalence of the information about it)

I know that polyurethane is made with isocyanates, which I'm wondering if that is leading to some people seeing that word and getting confused and assuming that there is cyanide in the foam.

What is confusing about this is that polyurethane is generally considered a very "laser friendly" material to cut (stated all over the place on laser hobbyist and professional websites under acceptable materials). Producing the same gasses that were used in gas chambers seems pretty darn dangerous and like there should be red flags up everywhere.

Can anyone here speak to the chemistry of this, firstly how much if any HCN would be produced by using a 10000nm laser (meaning intense heat based, but nonflaming cutting). And if properly ventilated with an industrial air handling system designed to move the full volume of air from the cutter outside many times per minute what are the risks involved? Does HCN bond to surfaces and stick around? Or is it fully ventilated as a gas?

Clearly, I'm not a chemistry expert, so looking for someone who knows more to help me understand what is real and what is just scary sounding jargon.

• Pyrolysis of PVC produces a whole slew of toxic chemicals, some worse than chlorine. See fire.nist.gov/bfrlpubs/fire87/PDF/f87015.pdf Carnegie-Mellon recommends a good exhaust system for any laser cutting: cmu.edu/ehs/fact-sheets/laser-cutter-safety.pdf Jul 11, 2017 at 22:42
• Thank you @DrMoishePippik, do you have any other information about the cutting of polyurethanes similar in scope to that NIST article you shared? That was extremely informative about PVC, but as I was using PVC as my null hypothesis case of what NOT to do, why not to do it wasn't my specific concern! Jul 11, 2017 at 23:59
• There are a number of sites about laser cutter exhaust systems or vent hoods, e.g. engraversjournal.com/article.php/2780/index.html , instructables.com/id/Build-a-laser-cutter-fume-extractor and commercial products. Ideally, the exhaust should go through some sort of filter, e.g. a water bath, to remove toxic chemicals (e.g. HCl) that would have been vented outside. Jul 12, 2017 at 23:33

Special hazards arising from the substance or mixture: carbon oxides ($$\ce{CO}$$, $$\ce{CO2}$$) nitrogen oxides ($$\ce{NO}$$, $$\ce{NO2}$$ etc.) hydrocarbons, isocyanate vapours and hydrogen cyanide can be released in case of fire.