A brief summary of fine particle, and volatile organic compound emissions during FDM printing processes
~TL;DR~
Studies found, that 3D printers generate a significant amount of fine microplastics particles during printing. They also generate volatile organic compounds (VOCs) during operation, mostly during heating up. Some filaments also smell bad. Microplastics are generally not healthy to inhale. VOCs even less so, as they are known to cause various health issues (cancer for example). This is true for all filaments, including ABS, PLA, PETG, although ABS like filaments are the worst offenders. Studies show, that short exposure to these exhausts is usually low risk, however prolonged, or frequent exposure can cause health issues. It is advised to use 3D printers in well ventilated rooms, and wear protective masks, while operating them. The usage of 3D printer air filters is also recommended.
Long version
Filament based 3D printers have a significant amount of emitted microplastics in them <pm2.5 region. Studies usually give the number of particles in a given volume of air. Measured particle number concentrations are between 103 – 105 particles/cm³ for 3D printing PLA filament and from 104 to 106 particles/cm³ during printing ABS, which is a 10 fold increase. The measured numbers depend on filament brand, print settings, the printer, and many other factors.
Printers also emit smaller particles, in the 100nm diameter range. Most of them are emitted during heating up, but some do form during printing, especially for materials like ABS or PVS. Differently sized particles behave differently, have differing distribution in the room the printer is placed in, and also have different health effects. <100nm particles are considered to be the most harmful emissions of 3D printing, as they can penetrate deeper into the respiratory system, and cause inflammation. Studies found, that increasing the print temperature creates smaller particles, while decreasing the temperature increases the mean diameter. The brand of the filament, and the material itself also creates differently sized particles, PLA being slightly better than ABS.
Scientists think, that the formation of these particles is due to the condensation of volatile organic compounds. When many particles are present, they stick together, and create an aerosol made up of larger particles. This process is shown on the figure below:
Gu et al. collected emitted particles on quartz filters. Chemical analysis showed that the particles mostly consist of semi-volatile compounds (SVOCs) derived from filament additives such as plasticizers, flame retardants and antioxidants or cyclosiloxanes, which may be used as lubricants in 3D printers (Gu et al., 2019b). The cyclosiloxanes were also observed when the 3D printer was not printing and only turned on (the printing bed was heated to 55 °C automatically). It is also suspected, that greater differences in melting, and printing temperatures contributes to VOC generation significantly.
In a study with employees regularly using 3D printers, 59% have reported respiratory symptoms (Chan et al., 2018). A case study published by House et al. indicates that users of 3D printers may experience respiratory symptoms, including asthma (House et al., 2017). In an experimental exposure study with human volunteers, Gümperlein et al. examined the health effects of desktop 3D printers using two filament materials: ABS and PLA. Healthy adults were exposed to emission of a desktop 3D printer for 1 h. The exposures had no noticeable effect on inflammatory biomarkers. However, there was a slightly increased level of exhaled nitric oxide after printing with ABS, which could have been caused by eosinophilic inflammation from inhaled UFP particles. Additionally, more people reported indisposition and odor nuisance compared to printing with PLA (Gümperlein et al., 2018).
In conclusion, using 3D printers in a poorly ventilated, closed area might present a long term health risk, and as such improved ventilation, or air filtering is recommended.
This article is based on:
Heike Romanowski, Frank S. Bierkandt, Andreas Luch, Peter Laux,
Summary and derived Risk Assessment of 3D printing emission studies,
Atmospheric Environment,
Volume 294,
2023,
119501,
ISSN 1352-2310,
https://doi.org/10.1016/j.atmosenv.2022.119501.
cover photo by Milwaukee VA Medical Center