Occasionally, we are asked whether it’s a good idea to put a 3D printer in a living room or study. After all, the machine is designed to melt plastic. And when plastic is melted, some amount of VOCs (volatile organic compounds) and UFPs (ultrafine particles) can be released into the air. So, how do you tell whether it’s safe? Sadly, no consumer 3D printer manufacturer on the market has proper certification and measurements for its machines – well, except for us!

In short:
The Original Prusa MK4S (and MK4), when used with our Prusament PLA and PETG, is the only consumer 3D printer to have the internationally recognized UL 2904 GREENGUARD certification, meeting strict safety standards for VOCs and UFPs. If you’re concerned about emissions and need a printer for your home, office, or classroom, this is the safest option available.

The GREENGUARD certificate of compliance issued by the UL company

What are the VOCs and UFPs, and what do they mean for the user?

VOCs (volatile organic compounds) are a group of organic chemicals with a low boiling point and high vapor pressure at room temperature, which allows the molecules to be released into the air. This group includes a large variety of organic chemicals, some of which are safe and even useful (various scents, communications between plants and insects, etc.), while others may pose a danger to human health or the environment.

For obvious reasons, we want to address VOCs dangerous for human health. These chemicals of concern may have various negative effects, ranging from headache, dizziness, and respiratory issues, to some chronic diseases, including cancer. The range of health issues may become even wider for children, whose bodies are still in development and the VOC may cause damage to their immune and neurological systems.

As for the UFPs (ultrafine particles), we’re talking about nanoscale particles with size less than 0.1 μm in diameter. These particles can be either carbon-based or metallic and due to their size, they can penetrate deep into the lungs, from where they can get to the bloodstream. These particles can then cause lung diseases, induce heart diseases, and other health issues.

These hazardous chemicals may be used in the manufacturing of various products and later released in the air with high temperatures, for example. Their toxicity is hard to guess without proper equipment, as some of them may be odorless and without any obvious physiological effects on the human body. And here’s the point, where the UL company with its GREENGUARD certification helps.

Particulate matter size comparison. Source: United States Environmental Protection Agency (USEPA).

What is UL GREENGUARD Certification?

The main goal of the UL GREENGUARD certification is to assess whether the product is safe to use by identifying and measuring the amounts of VOCs and UFPs released from it. For us, the testing criteria met the UL 2904 standard, which applies to 3D printers and 3D-printing materials. This standard was developed by UL following the requirements of the American National Standards Institute (ANSI) and the Standards Council of Canada. It provides a systematic test method suitable for desktop 3D printers. It primarily applies to measuring emissions from 3D printers in classrooms, offices, libraries, and other non-industrial indoor settings, where proper ventilation may not be ensured. The emissions selected by the UL 2904 standard are measured for ultrafine, fine, and coarse particles, where concentrations, particle sizes, and number of released particles per hour are measured. The series of tests is performed in a controlled environment, including a test chamber, a clean air supply system, and criteria that the setup needs to comply with.

Photograph of the Original Prusa MK4 3D printer in the environmental chamber at UL facilities (USA)

The test’s outputs are both measured and calculated exposure levels of VOC and UFPs, as well as the maximum allowable emission rate criteria for VOC and total particle emissions. When the detailed environment models are taken into account, it is decided whether the printer and the material meet the final criteria and are therefore suitable for use in non-industrial indoor places.

The UL company tested our Original Prusa MK4 and MK4S 3D printers with Prusament PLA and PETG, which are the most commonly used filaments. Both the printers and materials passed the testing criteria with outstanding results. Here, you may see the Certificate of Compliance.

Why is it good to have our 3D printers and filaments certified?

Having the UL GREENGUARD certification is a huge step forward. After all, the discussion about the potential dangers of VOC and UFP emissions during printing always resonates throughout the community. People are usually unsure whether it’s safe or not. And, they simply can’t be sure. The VOC and UFP emissions may vary greatly between filaments and printers, as there are many variables in printing temperatures, 3D printer parts, filament pigments, additives, etc. There is simply no way of guessing whether the combination is safe or not unless it’s tested properly.

We care about the safety of our products, both from the perspective of everyone who uses them, as well as anyone from our team who is directly involved in the manufacturing process. With the UL GREENGUARD certificate, we have solid evidence of fulfilling the safety criteria, measured by an independent 3rd party – the UL company. This can be particularly helpful, if you’re looking for a printer that will be used in a public space, such as a school, library, or any other sector, where safety is a must.

We are working to expand the certification on more of our printers. It’s a lengthy process, but we’re optimistic about the outcome. For example, in the case of our XL, we’ll be using the same proven materials and the Nextruder, just on different kinematics.

Since the certificate is valid when using our Prusament PLA and PETG, you might be wondering about other popular materials on the market, such as PC, Flex, ABS, ASA, PP, PVB, and various unique composites and polymer blends. When it comes to printing ABS, ASA, HIPS, and PA, you should definitely use the Enclosure with the HEPA advanced filtration add-on. For Prusament, we thoroughly test every new material before it goes into production. A recent hot topic in the community has been the potential health risks of carbon-filled filaments. To ensure our CF Prusaments are safe, we collaborated with the Czech National Institute of Public Health to test for skin irritation, cytotoxicity, and airborne particle limits. Only after confirming their safety did we start full production. You can read more about it in Josef’s tweet below.

PSA🚨 You might have seen the recent videos from @NathanBuilds or an article on @hackaday about the potential dangers of carbon fibers in filaments, comparing it to asbestos 😳 Given that we offer several filaments containing carbon fibers, I thought many of you would be… pic.twitter.com/SjTTbqGe4N

— Josef Prusa (@josefprusa) August 4, 2024

Finally, even with our certified printers and filaments, you can’t go wrong with taking extra precautions anyway, such as ensuring proper ventilation.

Happy printing!