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When I began reporting on additive manufacturing (AM) just five years ago, I quickly learned about the dangers of metal 3D printing, from the combustible materials to the risks from inert gas leakages. Working with powdered metal is no joke, which is why operators are often pictured in full PPE including respirator, fire-resistant jacket and nitrile gloves. If you ask one of these folks about safety, they’ll likely point out facility features like specialized fire extinguishers, spark-resistant flooring and air quality monitoring systems. There’s a considerable and widely recognized ecosystem of training and equipment needed to run these machines. 

But it wasn’t until more recently that I began to hear conversations about the safety of polymer 3D printers. I’ve been to my fair share of machine shops and other manufacturing facilities where a desktop 3D printer sits out in the open, no ventilation or enclosure in sight. The technology is so small, quiet and innocuous sitting alongside a milling or turning center that it gives off an impression of safety — an impression that may be somewhat misleading.

Desktop printers may not be running combustible powders or pose a significant fire risk, but they do bring at least one health and safety hazard: emissions. According to Aleksandr Stefaniak, industrial hygienist at the , there are two main emissions associated with the fused filament fabrication (FFF) style of printers commonly used to make prototypes, tooling, robot end effectors and more:  volatile organic compounds (VOCs) and ultrafine particles (UFPs). VOCs and UFPs are given off when the plastic filament is melted during printing, and as they cool, VOCs can condense onto the ultrafine particles and be breathed in by nearby humans. The emissions can irritate lungs and exacerbate asthma, among other side effects.

Many factors contribute to the quantity and danger of 3D printer emissions, including the material used, the temperature at the nozzle and within the build envelope, and the size of the room where the 3D printer is located. Generally, higher printing temperatures lead to higher emissions rates. A single printer on the shopfloor in a large facility operating at lower temperatures is less of a risk than one or more 3D printers running high-temperature filaments in a small room, for example. 

For organizations that want to implement FFF 3D printing, the  provides a hierarchy of recommended controls, from most to least preferred: 

1. Avoid the hazard altogether. The best-case scenario is to simply avoid emission risks in the first place. This could be accomplished by purchasing an enclosed 3D printer with the appropriate exhaust and filtration systems already in place, or choosing to build with low-emission materials such as PLA. Users should also avoid “hacks” to printers like swapping nozzles to achieve a higher extrusion temperature, as higher temperatures allow greater quantities of VOCs to be released.
2. Engineer the hazard out of the process. Engineered controls include adding enclosures to 3D printers that don’t have them and installing printers under a fume hood or local exhaust. Fans with carbon and/or HEPA filters can also help trap and remove VOCs and ultrafine particles from the air.
3. Implement administrative controls. If the risk can’t be avoided, set up policies to limit personnel exposure to VOCs and particulate. For instance, keep printers in a closed room that staff only enter when necessary to retrieve completed parts or perform printer maintenance.
4. Use personal protective equipment (PPE). Operators can wear PPE such as respirators and dust masks to avoid breathing in particulate. This is the least-preferred way of approaching the problem because it doesn’t address the source of emissions, and using PPE effectively involves additional training and fit testing. It also requires due diligence to confirm that the filters and cartridges used in PPE are the correct ones to remove the contaminants at hand. 

Check out  with Mr. Stefaniak and NIOSH researcher Lauren Bowers for more information, and to see how the printer farm above was ultimately enclosed and ventilated.