What every enthusiast should know about particulate emissions

3D printing is a passion and hobby for many of us. When the first successful print comes off the build plate, few people think about how harmful the little plastic smell coming from the printer can be. FDM printers are great tools for hobbyists, but they also come with health hazards such as ultrafine particles (UFP) and VOCs. You can't see these and you can't smell them all, but research shows they have harmful effects on human health. This text is written to help the user understand the health hazards associated with printing, and to provide solutions to manage them.

What do studies say about emissions from 3D printers?

One of the basic studies that has explored this topic is a joint study by the Illinois Institute of Technology and UL Chemical Safety (Stephens et al., 2013), which found that FDM printers can produce hundreds of millions of ultrafine particles per minute during operation. ABS was clearly the highest emitting material, but PLA, despite its lower odor, also released UFP particles, although in significantly smaller quantities. Later studies, such as Azimi et al. (2016), confirm these findings and show that emissions are primarily due to filament heating and its degradation products.

VOCs have been studied particularly in connection with ABS printing. Davis et al. (2019) found that ABS releases styrene during printing, which is classified as a possible carcinogen and a known irritant to mucous membranes. Although PLA is considered so-called safe, it also released VOC emissions. PLA's VOC emissions are lower, but they cannot be completely ignored. When PLA is heated, smaller aldehydes and lactone compounds are released, the concentrations of which can increase in small rooms.

Why are ultrafine particles and VOCs a problem?

Ultrafine particles, as their name suggests, are so small that they can travel to the deepest parts of the lungs and therefore enter the bloodstream. Studies have shown that long-term exposure can increase respiratory symptoms, inflammation, and in some cases affect the functioning of the cardiovascular system. Limited long-term research is available on the subject.

The effects of VOCs depend on the substance. Styrene causes headaches, irritation and fatigue even at low concentrations and is recognizable by its pungent odor. Long-term exposure to styrene increases the risks, especially in poorly ventilated spaces. Unfortunately, many hobbyists often have their printers in offices, bedrooms or other small spaces with poor ventilation and frequent use.

How you can reduce exposure

Hobbyists often face the challenge of simply not being able to place their printer in a separate space or one with proper ventilation. However, even with limited space and a small budget, exposure can be limited.

The first and most important factor is ventilation. When you print in a well-ventilated space, VOC concentrations are quickly diluted and ultrafine particles are removed from the air before they can accumulate to dangerous levels. For example, simply opening a window helps a lot, but due to the Finnish winter, it is not a very permanent solution. However, when printing is long-term, a separate exhaust air solution and air filtration are recommended, as simply opening a window does not remove emissions effectively enough.

It is a good idea to combine good ventilation with printing inside a chamber. The chamber prevents the effects of air currents caused by ventilation on the print, improving the quality of the print and enabling a wider range of materials. When printing in a chamber, emissions spread more slowly to the environment, enabling effective filtration already inside the chamber. Many hobbyists build a chamber for their printer anyway, so adding an air filter to the chamber is a small hassle compared to the benefits. Some newer printers already include a sealed chamber with an air filter.

Filters are a very useful solution for hobbyists in addition to ventilation. The HEPA filter collects UFP particles, and the activated carbon, in turn, binds VOC compounds. Nevermore-type activated carbon filters (an open model of the Voron project) and Bento Box solutions are widely used in the 3D printing community. Their advantage is their adaptability and affordability. There are also ready-made HEPA + activated carbon combination filters on the market, which can be installed in enclosures or separate air purifiers.

Material choices can also significantly affect the amount of odor and particles, but they are not the solution to the problem. PLA, PETG and other low-temperature materials produce less harmful emissions than, for example, ABS or nylon. If ABS must be printed, enclosure and ventilation become especially important, especially if you have to stay in the same room.

What solutions do we use?

Our printers are in a separate room, where the air movement is arranged so that the room remains at a lower pressure than the rest of the building. Negative pressure is created with a simple solution: a removable insulating foam board is placed in the window, with a hole made for an exhaust fan. The fan constantly moves air out, allowing replacement air to flow into the room from elsewhere in the interior, and emissions from the printers cannot spread elsewhere.

All printers that we use to print high-emission materials such as ABS have a chamber, and inside them are DIY filters that utilize activated carbon. Mainly Nevermore and Bento Box filters. The filters reduce VOC concentrations directly inside the printing chamber. The general ventilation of the room ensures that no remaining particles or gases can accumulate. As a result, the styrene smell in the printing room is noticeable, but much smaller than without these measures. The room also does not emit a noticeable odor into other rooms in the building. In addition, we avoid being in the printing room when the printers are printing.

Summary

FDM printing is a versatile and rewarding hobby, but it also comes with some issues that you should be aware of. Ultrafine particles and VOCs are harmful, but the solutions to control them are simple. When the printer is in the right place, the air is well-circulated, the chamber and filtration are in order, and the necessary material choices are considered, odors and harmful gases are kept under control.

Sources

Stephens, B., Azimi, P., Orch, Z., Ramos, T. (2013). Ultrafine particle emissions from desktop 3D printers. Atmospheric Environment, 79 , 334–339.

Azimi, P., Zhao, D., Pouzet, C., Crain, N., Stephens, B. (2016). Emissions of ultrafine particles and volatile organic compounds from commercially available desktop 3D printers. Environmental Science & Technology, 50 (3), 1260–1268.

Davis, J., et al. (2019). Characterization of volatile organic compound emissions from consumer fused deposition modeling 3D printers. Journal of Occupational and Environmental Hygiene .