China produces millions of consumer-grade 3D printers every year and sells them all over the world, a relative part of which is used by users in their homes or offices. The question is, how is the safety of 3D printing?
When the air is filled with the wonderful smell of melting plastic, it is precisely at this time that 3D printers are working hard. But you may have seen the news that 3D printing was toxic in the media last year, and you must have worried: "How harmful are these gases emitted by 3D printers to the human body? If you put a 3D printer in the bedroom and let it run overnight, it will be harmful to the human body. Is it harmful to the body? Will it affect the health of employees if the 3D printer is placed in the office?
What are these gases composed of? Will it cause cancer?
Studies have shown that all 3D printers (this article mainly analyzes FDM/FFF 3D printers, and light-curing and other technologies will be followed up in the later stage) will produce emissions when printing, some of which are harmless but have odors, which are caused by material heating Produced later, others may be hazardous to health. To judge whether these emissions are safe, pay particular attention to the levels of particulate matter (PM) and volatile organic compounds (VOCs) emitted by printers.
Inhalable Particulate Matter (PM): Usually, the particulate matter inhaled by people will accumulate in the lungs. If the level of particulate matter is too high, it will cause respiratory diseases, such as asthma. In addition to 3D printers, these particles also appear in daily life, such as car exhaust, wildfire burning, etc. PM2.5 is also a pollution index that we often pay attention to in our daily life.
Volatile Organic Compounds (VOCs): VOCs such as formaldehyde are often of particular concern when renovating or purchasing a car. Last year, as related news reports said, some VOCs from 3D printers are carcinogenic, but the toxicity of these emissions has not been fully studied, and the investigation is still ongoing.
Although detailed investigations are still underway, the magnitude of the hazard to humans from FDM emissions depends on the operating environment and exposure time. A 2021 study found that human exposure to emissions for an hour or less has no health effects. But those who work more than 40 hours a week around the printer are at risk of developing respiratory problems. The grayscale region between 1 hour and 40 hours still needs to be further verified by experiments.
While data and conclusions about children are also being studied, we need to pay more attention to what is happening in schools, especially in 3D printing innovation labs in schools. A study by the U.S. Environmental Protection Agency (EPA) on 3D printer emissions suggests that children may be particularly vulnerable to 3D printer emissions. The study found that children between the ages of 9 and 18 had a larger surface area of their lungs covered by particles after inhaling particles emitted by 3D printing compared to adults. EPA believes that this may be related to children's greater curiosity and preference for close contact with the print head and that children's respiratory tracts are still in the developmental stage and are susceptible to infection.
How to reduce possible health risks when using 3D printers
Use low-emission material (such as PLA) and choose original or brand wire
First, the biggest factor affecting FDM emissions is consumables. According to several studies conducted by the U.S. Environmental Protection Agency (EPA) and other departments, the type of consumables has a crucial impact on emissions, depending on the raw materials used by the manufacturer and the intermediate synthesis process - different consumables contain different toughening. , coloring, and other additives, which are affected by hot melt differently. The U.S. Food and Drug Administration (FDA) also recently stated, “As the application of 3D printing technology becomes more and more extensive, it is necessary to investigate the impact of consumable additives on human health. In the future, the FDA will continue to investigate other additives and related characteristics of volatile organic compounds and particulate matter, and relevant standards have been issued.”
Most of the current FDA research focuses on the three most common consumables—ABS, PLA, and nylon, with ABS generally classified as a high-emitting material. When ABS is used, a large amount of PM and VOCs will be generated at the beginning, and then the emissions will be stable throughout the printing process. As mentioned above, because the emitted VOCs will quickly combine with particulate matter and become one, the main subsequent emissions that are continuously generated are basically particulate matter. PLA and nylon materials emit less emissions than ABS when used. These materials also generate large amounts of particulate matter when first used, but do not emit continuously. So generally we call these materials low emission materials.
At the same time, they also noticed that the emission of PLA will be affected by the brand of consumables. The quality of consumables of different brands is uneven, and the emission of some PLA is even close to the emission of ABS. Rodney Weber, a researcher at the Georgia Institute of Technology, discovered this after conducting experiments on consumable emissions back in 2017, and he urged users to be cautious about buying cheap, unlicensed consumables. He said, “We found that printing with cheaper filaments produced a higher concentration of aerosols than using filaments made or recommended by original or well-known brands. Although PLA is made from biodegradable materials such as cornstarch, we and the Aerosol Association have found that some PLA emits particles and compounds that are even more toxic than ABS. But because PLA only produces these harmful substances at the very beginning of printing, over time, ABS consumables emit The toxicity of the material will gradually exceed the toxicity of the PLA consumable emissions.
Setting optimization: finer nozzle, lower nozzle temperature, and choose the best effect
Second, hardware parameters vary from manufacturer to manufacturer, and these parameters can affect emissions. Especially when using PLA filament and nylon filament, the influence of printer brand and parameters is more obvious. Some settings also have a huge impact on PM and VOC emission rates.
The Brno University of Technology conducted a study in which researchers compared the effect of printer settings on ABS, PLA, PET, and TPU materials. The results show that when we choose the optimal print settings, we can ensure successful printing while minimizing emissions; at the same time, when the nozzle temperature is set lower, the material will produce fewer emissions. Therefore, from a respiratory health standpoint, the researchers recommend that printer users set the lowest nozzle temperature possible, even lower than what the manufacturer recommends. The study also found that nozzle size had a significant effect on both discharge rate and particle concentration. For ABS, PET, and PLA materials, they found that the use of a 0.4mm nozzle produced the least PM. The exception is TPU, which increases the nozzle size to 0.6mm with fewer emissions.
The findings also show that material flow or printing speed barely affects emissions. Therefore, extruder settings are the most critical factor affecting emissions. Another study using ABS and PLA tests found that a heated print platform did not increase emissions, but instead helped increase particle size, making it easier to reduce particle counts.
Nearly all researchers point out that proper ventilation is the key to improving indoor air quality. The user should put the printer in a well-ventilated location, and install a fan on the exhaust port, so as to achieve the best effect. All ventilation systems should be equipped with appropriate air filtration systems for use. A high-efficiency air (HEPA) filter is recommended, which removes up to 99.95% of particulates. To reduce VOC emissions, activated carbon filters are the best solution.
For open printers, add other supporting devices
It's a good idea to cover your 3D printer with a small vented enclosure with an air filter. Studies have shown that placing a desktop 3D printer in an enclosure with filtered ventilation can reduce particle emission rates by 97%. However, it should be noted that when purchasing, you should check whether the purchased shell has a HEPA system because many 3D printer shells on the market are only used to maintain heat and have no emission effect.
Air purifiers use fans to draw air in and remove various pollutants through various filtration and disinfection methods. They can go a long way in improving the air quality in a 3D printer's work area, but it's best to use an air purifier with HEPA and activated carbon filters. Be very careful when shopping for air filters, as filters designed for dust and partitions may not completely remove particulates or VOCs emitted by 3D printers. Remember to replace the filter on the machine regularly.
Printer enclosure for HEPA filter
Install air quality monitors indoors
Air quality monitors can help users monitor the levels of potentially harmful chemicals in work areas in real time. However, studies have come to mixed conclusions about whether consumer-grade monitor products are sensitive enough to detect the tiny particles emitted during the 3D printing process. One study showed that the vast majority of solid particulate material emitted from consumables was between 0.05 and 0.2 microns in size. Most home air quality monitors can only detect particulate matter between 1 and 2.5 microns in size (defined as PM1-PM2.5). However, there are some monitors that can detect particles below 0.1 microns (defined as PM0.1).
Some studies have pointed out that air quality monitors are not necessarily reliable, even in advanced research sites. But if your monitors show that PM levels are already above 35 micrograms per cubic meter, it's time to start looking for ways to clean up your work area emissions.
Summary With the development of science and technology, more and more classrooms, universities, and enterprises will use 3D printers because they can play a huge role in education and scientific research. Although the current data is still insufficient to support the establishment of industry standards, we still need to pay special attention to potential hazards, prevent problems before they occur, reduce possible occupational hazards, and protect children from incidents similar to melamine in the past.