Is 3D Printing Safe? or DIY Testing for HCN from ABS and Nylon 3D Print Material

Picture of Is 3D Printing Safe? or  DIY Testing for HCN from ABS and Nylon 3D Print Material
  By 3D Printing, we are referring to the majority of FDM or filament feed, BukoBot, Printrbot, Makerbot, TOM and others that use plastic line and a heater block to print parts.
   And, what exactly is "safe" anyway..?
If we eliminate the obvious, the fact that the belts and motors can pinch a finger as well as a heater block operating at 200+c will definitely burn you, we are left with the one unknown.  That is of any hazardous fumes and odors that may be emitted by heating the plastics.  We not only can't see these gasses, but most of us don't have a device at hand to make a measurement.  
    The intent of this DIY is to explain how to build a test apparatus to determine the safety of the material you are using to print your parts.  Of course in doing so, we were able to measure and report on various common matereials.

    If you just want an answer to the question "Is 3D Printing Safe" without reading the excruciating details, you're in luck.

"Yes" Based on our measurements using the world Safety Authorities (OSHA NIOSH ACGIH) Limits, 3D Printing is safe.
There was NO measured HCN from "3D Printing ABS" based materials at specified temperatures.
There was NO measured HCN from "3D Printing Nylon" based material at specified temperatures.
There was 0.1ppm of HCN while printing with a "Non-3D Printing" material (Trimmer Line)

Even in our worst case testing in an enclosed 12" cube at 420C (788F) for 10 min the maximum reading was 1ppm, again, trimmer line.  The OSHA safe limit is 4.7ppm.

Quick Q and A

    Did you find any items of note?
  1. We found that before the threshold was reached, the plastics became "unprintable" and would halt/jam the printer.
  2. There is a lot of naturally occurring HCN.  You will probably encounter more HCN at an outdoor marshmallow campfire than we measured in our testing.  Due to it's shear quantity as opposed to the small quantity we print, burning wood creates a lot of HCN.  
  3. Again, our testing shows no HCN measured from 3D Printing materials at correct temperatures.

     What gas would make 3D Printing unsafe?
An excessive amount of Hydrogen Cyanide (HCN) - A gas emitted by plastics when they are set on fire or breach pyrolysis.

     And what is an excessive amount of HCN?
The international (OSHA NIOSH ACGIH) maximum allowable exposure to HCN is 4.7ppm

    So? How much HCN did you measure while actually printing?
3D Printing  ABS from various 3D  Printing material suppliers in China, the EU and US = None
3D Printing Nylon from taulman3D 3D  Printing material supplier in the US = None
Two brands of Trimmer or weed-whacker Line mfg in the US = .1ppm

     Where did you get the 3D Printing material?
Defined 3D Printing Material -
ABS1 = China - A
ABS2 = China - B
Nylon1 = US
Nylon2 = US

Non 3D Printing Material -
Trimmer1 = US
Trimmer2 = US

      What did you use to measure the HCN?
Industrial Scientific Corporation T-82 Single Gas Monitor
Calibrated HCN Sensor
Certified calibration 1 day before testing
Certificate of calibration
Certified by UL, CSA, CE
Resolution .1ppm

    What was your absolute highest reading?
Trimmer line "A" at 220c+ = 0.6ppm -1.0ppm in a semi-sealed enclosure (12" x 12" x 24") for 10 min
This is a "cumulative test" as the gas is allowed to accumulate in the enclosure, thus it's concentration in ppm is higher.
This is NOT a printing test, but one of several tests done to answer cumulative concentration questions.

Excruciating details,


     Today, most 3D Printers use modular power supplies.  Either re-purposed ATX (Computer PS) or enclosed wall power units, such as used by laptop computers.  These are already UL listed and tested.  Most of these power supplies don't exceed 24 volts, including power to the Hot-End.

     Again, there are obvious safety concerns with respect to motors and belts, pulleys and or threaded rods.  However, once we see these components in operation, we know to use a bit of caution and not stick our fingers in the moving parts.

      There are a few hot components we need to be aware of.

  1. Stepper motors - These can get hot, but usually not hot enough to burn you.  Most motors have an attached fan to keep them cool so as to last longer as heat damages the motors bearing surface over time.    
  2. Power supply - These are covered units, but as they dissipate heat we need to make sure they have access to ventilation, i.e. don't block the little cooling holes and replace air filters when needed.
  3. Build table - These are the platform we actually print onto.  They are usually heated to a temperature that will burn you.  Almost all of these are vividly marked in some manner warning of "HOT" and "Do Not Touch".  This is an actual UL requirement if the printer is certified.
  4. Hot-End or Heater block - This is the component where the plastic is melted and flows from a small opening/nozzle. This will be very hot.  Between 180C (356F) and 275C (527F).  Again, this will not just burn you, but mark you for life.  Recently, you may have noticed that some 3D Printers have started to ship with brackets, or shields around the Hot-Ends.  And in some cases, a completely enclosed printer where access is only through a door or lid.  This comes from various UL and CSA requirements for finished goods where rules to protect the consumer come in to play.  As of yet, 3D Printer kits have not been required to meet a lot of the same rules. 
    While most of us have tape measures and wrenches to make mechanical measurements/adjustments, volt meters to make electrical readings and temperature sensors to measure hot parts, almost none of us have unique gas detection equipment to detect gasses emitted by printing.  And because we are changing the state (heating and melting) of plastics, they will emit  fumes and odors.
3D Printing Measurement History
      We can't say that no one has made this specific measurement prior to now, just that we were not able to find any information on-line or through contacts.
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werose3 months ago

good point we shall not accept any dangerous chemical material to safe our people

jnordstrom5 months ago

If interested, my company, 3DPrintClean is developing a 3D
Printer filtration system that filters fumes, unpleasant odors and dangerous concentrations of
Ultrafine Particles, making
it safe to print in homes and offices. In addition, the solution improves print
quality by reducing warping, curling and cracking. See 3dprintclean.com for details.

a-morpheus1 year ago

What about this announcement?:


You are correct, a-morpheus...while there seems to be a lot of downplay about the gases being released, we SHOULD be paying particular attention to the particulate matter that is. From a recent report (

http://ecoh.ca/health-safety-hazards-associated-3d...) :

"A recent study tested a commercially-available 3D printer and found
significant emission of ultrafine particles in the size range 15-65
nanometers (nm). When inhaled, ultrafine particles (defined as particles
less than 100 nm in diameter) deposit efficiently in the deep parts of
the lungs. The study also found that use of the ABS plastic produced
approximately 10 times as many particles as the PLA plastic. For
comparison, ultrafine particle emission rates from the 3D printers were
similar to the emission rates observed during grilling of food on gas or
electric stoves.

Recommendations to reduce exposures to the emitted fumes and
particles include mechanical ventilation with dedicated exhaust,
enclosure of the printer, filtration, and choice of a lower-emitting

lsnilsson7 months ago

I agree that ventilation is best, the level of flow is the concern I have. Keep in mind that you are only trying to prevent outgassing into the breathing space, not operate a high volume paint booth.

I live in Alaska and it gets cold enough up (try -60 deg F) here that, if you have a high volume fan, you can EASILY overpower the heaters in these printers if you direct vent with outside to outside air (that is, a loop that draws and vents to the outside environment). All that is really necessary is a decently sealed containment (make a box and silicone the edges) with a small hole in the bottom front left side and a "vent" hole in the top right back side.

Now a small air pump, which will also likely be pretty quiet, can be mounted to the interior of the box and a small vent hose (we are talking like a quarter inch here) can be fed through the vent hole and to the exterior (careful if you drill through a wall...) In a house I would try to vent to a ventilated basement or attic if possible. Mount the pump inside the enclosure to mitigate any minor sound. I like plexi for the front door because it is nice to be able to see inside... If you want a full seal, add some latches to the closing door.

This will allow a positive draw into the box without making the air exchange at a crazy rate, and allow it to be pre-heated in the room. You only need to exchange the air once an hour or so to maintain negative pressure inside the enclosure without completely cooling off the printer unit. You could have a higher capacity pump if you want to do a true PURGE at the end of a print, but I doubt that would be a big deal. Some projects that take hours to print would probably benefit from a rig like this, for both particulate and suspended gas mitigation. My two cents.

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vortexmax2 years ago
Hi if is doubtful do the right thing build an enclosure with a venting mechanism. I have been a research chemist who has always erred on the side of caution. Wear a mask and wear nitrile gloves. Never approach these thing without protection. In forty years in chemistry I have observed many guys dying at 40 years of age. Inhaling all these wonderful compounds. I am healthy and 80 many of the others expired from all the overdosing in the air. I never take a chance on any unknown product always used caution.
+1 to venting. My printer is located in a 6x12 shed, one of the first things I did was build a vented enclosure for drawing fumes outside. The venting can also be detached and used for extracting solder fumes =)
chimera152 years ago
Really interesting...so it won't kill you outright...but does that mean that it wont give you cancer in 5 years if you're in your bedroom printing with abs 24 hours a day? I know I can barely stand the smell after a few hours and feel like I'm already growing a tumor...so it can't be completely harmless. I'd like to see a study of all the vapor that abs/pla/line gives off..and what exactly the hardness is of each of them, and if there's a difference between american and chinese abs for instance in the qualities. This is really an interesting subject.
Hey,chimera15, sounds like a great "ible for someone who wants all those answers, to actually do. Seriously.
samurai12002 years ago
Invaluable information in this not-so-'ible 'ible!!! Thank you for going through the steps.

HOWEVER, I do have a question: What is causing me to get a headache when I print ABS after ~20 minutes? I mean, the HCN levels might be of an OSHA-approved level, but I wouldn't be getting a headache if my body was OK with the altered environment.... My room is roughly 20x20x20 feet and i am generally at the opposite corner of the room when i am printing (so my guess is i'm exposed to the lowest PPMs over there).
taulman (author)  samurai12002 years ago
1200, It's of course difficult to say, however, there are actions you can take to make a determination as to further actions/resolutions:
1. If you're not currently vented, then add a simple vent as shown in the two renderings in the ible. A sufficient vent is made up of a standard 100cfm fan (as in most desktop comp) an inverted storage box and some 6" dryer hose to an exit.
2. Most overlook the fact that some stepper drivers emit a lot of noise just above the audio spectrum that can still have an affect. Try running a few prints with no heater and no material letting the stepper go thru their routine.
3. The material its self. There are suppliers that sell "odd" colors. Our China contact told us that these "odd" colors may be injection house purges and reject remelts. Reputable dealers will only sell virgin material.
4. Styrene can be a source of your issue as it does not dissipate easily. You may want to run the same test as noted in the ible and measure for styrene or "combustible gasses". If so, do a search on materials that emit almost no odor by others in their blog, IRC and wiki comments.
5. Long term exposure to levels higher than 1-2ppm of HCN have shown to cause similar symptoms but again, we saw no low level (0.1ppm) readings within proper operating temperatures excluding trimmer line.
6. Check out the following link for additional low level emissions that you may be sensitive or allergic to.
And again, as we say in all of our ible's, one should "vent all fumes and odors"

ah, some awesome points to consider. but yeah, it seems the only real way to make sure youre not harming your noggin is to vent to the outside world...
...and make it someone else's problem?

Perhaps the 3D community (that includes me) needs to think this through a bit harder.
So, then, what do you suggest? Charcoal filters on an active exhaust?
That's what I'm looking at, but 'science' must have looked at this already. I'll be looking around some more.
ps I wasn't having a go at you, my interim solution is an open door/windows to the outside...
Well here's what I'm thinking -- I agree with you that "science" must have looked at this already, and therefore determined no need to change the status quo, i.e. venting directly into the environment.

I remember reading a paper that said heating filament to the levels needed for FFF yields insignificantly low outgassing from both PLA and ABS. It'll take some digging to find the paper, I didn't bookmark it.

I would imagine that this would change once FFF printing becomes ubiquitous (= higher volume of by-product gas in the atmosphere.
evileddead2 years ago
Just so you know in the future, Cyanide has that tell-tale almond scent and taste, as do most compounds it's a part of.
@evilddead- about 1/3 of the population cannot smell cyanide, and of those who can, it deadens the nose to it in short order.
taulman (author)  pmowers2 years ago
pmowers, you are absolutely correct as this 1/3 note was part of every techncal paper we were able to aquire in our research. There were a few technical documents that implied that this had been tested for, as part of larger tests however, these may be paywalled studies. Thanks for your clarification.
pmowers taulman2 years ago
My background is laboratory medicine and we used a cyanide compound to measure hemoglobin in blood. There were a fair number of students and techs who could not smell it, while I could tell it across the room. One of the reasons that HCN was used as a chemical weapon (blood agent) was because it would numb out the olfactory nerves, while at the same time stimulating the respiratory centers of the brain. This is the reason that states use it in the gas chamber, you cannot hold your breath, one whiff and you have to breath more.
taulman (author)  evileddead2 years ago
You are correct as this is also noted in the able in section 2 as an alternative detection method.
BobCat2 years ago
Excellent work. Instructables needs more careful, rational, and scientific work like this. A *lot* more. :)
taulman (author)  BobCat2 years ago
BobCat, again thanks for your comments!
As mentioned in the ible, there were other materials tested along with 3D Print ABS and 3D Print Nylon. The 2BEIGH3 has hot ends capable of temperatures that will accomodate Tin and Bismuth metals. As new 3D Printing materials come on-line, it's our hope that others jump in on test procedures and methods.
Today, you can run polymer and co-polymer combinations and calculations and litterally have the combination extruded for you at any one of several houses. We beleive that this is an excellent move forward in 3D Printing and look to others to add their ibles on test and procedures.
taulman (author)  BobCat2 years ago
BobCat, thanks for your comment!
KahlZun2 years ago
wait.. you can use weed-whacker plastic in a 3d printer??

Ya, go to the reprap page here:
makermike2 years ago
This is a nice Instructable with better than usual rigor in its testing. However, speaking as a chemist, I also wonder about what other things are outgassing from the hot plastic. HCN and CO are certainly to be worried about, especially since CO is odorless, but as other commentors have noted, there is a smell associated with 3D printing. If you're smelling something, then something is volatilizing from the hot plastic. What?--probably a mixture of a bunch of things, a complete characterization of which is likely beyond DIY science, although I'd be surprised if someone hasn't written up a paper on it already.

So common sense would seen to dictate some level of precaution. Venting your work space would be nice, and don't sleep next to a working printer. Is it any worse than breathing in solder flux fumes or sawdust? I don't know.
taulman (author)  makermike2 years ago
Makermike, First, thanks for your comment. We agree, in that venting is always the best approch. We do not want to get into a vendor to vendor comparison as those that wish to can use this ible for that. However, with a little research, we did find comments on blogs from those that had found ABS materials that gave off almost no odors. We did not test that specific material but again as you note, some sort of comparison testing would seem like a worthwhile effort for someone in the 3D Printing community.
As a technical note, in that the process from solid to melted back to a solid takes place in a volume the size of the eraser on the end of any pencil, it seems that a simple well placed miniture vacume hose/line would all but eliminate most fumes and odors.
mgalyean2 years ago
Very well organized. I like the "how to do science" instructables in general, but this is really good. Excellent breadth and depth covering the method, materials, regulatory levels, hazards, etc.
taulman (author)  mgalyean2 years ago
magalyean, thanks for your kind comments. It does mean a lot to us as you can see that there is considerable time, effort and equipment involved. But of course, well worth it to the community!
No really, while I truly am excited about the "maker" culture exploding around us, being a nerd/tinkerer myself, there is so much disrespect for what has come before in many cases, and most disturbingly sometimes a seeming disrespect for rational thought itself at times (my young stepson still swears he could build an over unity generator out of permanent magnets; he has it "all in his head, just needs to work out a few niggles"). I just smile and tell him to build a prototype that works and I'd be overjoyed to admit that I, and Isaac Newton, and the entire edifice of human science to date really, is full of crap. It is simply refreshing to see a 'structable like yours that instructs in solid methods of rational thought after watching my son spend hours on the internet ooh'ing and ah'ing over the youtube videos that "prove" he could build one. He just doesn't get that he is getting intellectually punked by either smart-assed pranksters, or by self-convinced nutcases. Hey, I'm glad he is curious. I just want him to be smart-curious, not gullible-curious! :^D
taulman (author)  mgalyean2 years ago
mgalyean, as a side note, you should have seen the look on our taulman3D physicist face when I told him we were going to generate hazardous gasses and watch as we took videos of the process in real-time. There was this long pause and he just said "intentionally?" He then gave us all a quick course on safety!
taulman (author)  mgalyean2 years ago
Yes, I learned the lessons early on, as a young wild-eyed engineer, I was lucky enough to bump into a much older engineer who after gracefully listening to my ramblings of “new stuff” commented the following:
An inventor’s dream is the relentless elimination of technical roadblocks and the only successful inventors are the ones that see the “law’s of physics” as a guide, rather than a roadblock!
I'm always pleased to see kids actually "doing" rather than watching.
iortolan2 years ago
Nice article, thanks.
taulman (author)  iortolan2 years ago
Thanks for your comment!
fazgard2 years ago
Thanks for the great write up and discussion on all of what I would call 'nagging FaQ's' that sit in the back of the mind ..

Well done.
taulman (author)  fazgard2 years ago
fazgard, thanks for the comment! Again, it is our hope that others can use the ible to test new and inventive materials for 3D Printing as it's relativity easy to have extrusion houses mix new polymers.
BeforeTron2 years ago
REALLY REMARKABLE! I had a nagging concern about my 3D printer offgassing some type of "bad-ness".
I print PLA, and I have been told it is completely safe. If ABS is this safe, then I can only (emotionally) feel good about printing PLA. (of course I would have to test to make sure!)
This was so comprehensive and such an incredible public service announcement.
thank you so very much!!!!
taulman (author)  BeforeTron2 years ago
First, thank you for your kind comments.
We've only heard good things about PLA. Some quick research would define what gasses to look for if any and what the proper equipment would be to test.
Again, thanks for the comment!
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