3D Printing: A Lung Hazard

Discussion has escalated around whether or not 3D printing negatively affects lung health and NIOSCH researchers are making their case.  Inhalation of VOCs (volatile organic compounds) and ultra-fine particles from fused filament fabrication 3D printers have posed concern. Approaches are being developed to eliminate, avoid and reduce operator’s contact with 3D printing lung hazards and to find solutions.

“With injection molding, you’re putting the melted plastic into a closed mold that is stationary,” she says. Forming the part can take as little as a few seconds, and all the melted material is contained within the mold. “But with 3D printing, melted material is moving in all axes in the build chamber, and a large part could take hours to print. Particles can remain in the air for longer periods of time during printing versus injection molding.”

“Even enclosed printers don’t necessarily protect users from these emissions, she notes. Often these enclosures are designed to maintain a constant temperature environment for 3D printing, not necessarily to control the release of potential contaminants. With many FFF printers lacking appropriate filters or enclosures at all, there are opportunities for particulate to escape and cause potential health risks to operators.”

Aleksandr Stefaniak, industrial hygienist at the Centers for Disease Control and Prevention, describes how VOCs can end up in the lungs.

“First, the melting plastic gives off volatile organic compounds (VOCs) and ultrafine particles (UFPs) that can spread throughout the vicinity around the 3D printer. But as they cool, the VOCs can condense onto these ultrafine particles, which can then be breathed in by nearby humans. These particles can irritate lungs, exacerbate asthma and potentially carry other problematic compounds into the respiratory system.”

Studying 3D Printer Emissions

“The goal of this research is not to appraise specific printer models or give a pass/fail rating. Rather, NIOSH takes the data it collects and calculates the printers’ emission rate, being the number of particles released per minute or the total number of organic chemicals released per minute. This information can then be used to model different scenarios.”

This research is designed to educate companies that operate printers in an office environment, what type of impact their printers are generating and the level of hazardous impact. Different amounts of printers an project will result in different exposure.

How to Contract the Risks

NIOSH offers a Health Hazard Evaluation program that helps companies or individuals assess any potential risk associated with their 3D printing projects. There are four levels of recommended controls, moving from most to least preferred.

Avoid the hazard altogether. The best-case scenario is to simply avoid 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.

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.

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.

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 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.”

Pursuing the Best Case Scenario

An “ideal 3D printer farm,” was designed by the NIOSH researchers as an instructive example after completing an HHE analysis.

“The company in question had two shelves of open FFF 3D printers in a small room; administrative restrictions were already in place, with operators generally only entering the room to unload parts or refill filament. But with jobs running for hours at a time, often overnight, the buildup of particulate and VOCs could become significant.  ‘After the printers had been running for 10 hours in this enclosed room, someone would come in at 6 or 7 in the morning and get a big hit of whatever’s in the air,’ Stefaniak says.

NIOSH’s recommendation involved building Plexiglas doors and walls around the printer shelves, and integrating a fan equipped with a filter to trap VOCs and particulate, as shown below. “Once they started operating that fan, within just a matter of minutes the particle concentration in the room dropped by more than 99%, and the organic chemical concentration dropped by 68%,” Stefaniak says. “That’s the ideal setup, to have things in a room not accessed by a lot of people where the printers are being ventilated.”

It isn’t always the 3D printing itself that poses a risk…”It could be something you do to get the printer ready, or when removing the part, or during postprocessing. We’re trying to break down the process from beginning to end into specific tasks, to understand what’s happening during each one in terms of exposure potential.”

Locate the full article here.

 

Categories: Design & Process