Can filters be used to reduce 3D printer emissions?

The short answer is no.

As a Maker who uses 3D printing extensively in a range of projects, a recent scientific study into the particle emissions from 3D printers, highlighting several potential health concerns, was as concerning to me as it was too many other 3D printer operators. The study, conducted by scientists from the Illinois Institute of Technology and the National Institute of Applied Science in France, measured ultrafine particle emissions from consumer grade 3D printers using both PLA and ABS. This post will go into greater depth about the study itself, its findings, and the potential health implications for 3D printer users; but the conclusion of the study prompts questions about the best way of reducing exposure to emissions from 3D printers. “These results suggest caution should be used when operating some commercially available 3D printers in un-ventilated or inadequately filtered indoor environments.”

Since most 3D printing hobbyists use their 3D printers in small rooms in their homes or small office spaces, they are unlikely to be well ventilated. Therefore, the option to enclose a 3D printer and filter air out of the enclosure before blowing it into the room is an option utilized by many. Even some major 3D printer manufacturers are beginning to design sealed build chambers.

This is the Zortrax M300, a 3D printer design with an enclosure.

While enclosing a 3D printer can have a number of benefits both to printer operators and to the printing process, including reducing noise, reducing unpleasant smells, maintaining a higher ambient temperature around the print, and reducing drafts, can enclosing and filtering 3D printers reduce exposure to the kinds of potentially harmful emissions measured in the study?

What are Ultrafine Particle Emissions

To fully understand the results of the 3D printer emissions study, it is important to understand the types of emissions the scientists measured and how they made their measurements. The study measured the quantity of ultrafine particles (UFPs) given off by 3D printers during operation. To measure the particles, the scientists ran identical prints on a pair of 3D printers in a closed, furnished office space. The room was borrowed from a real company that uses 3D printers for their business so the experimental space was a good analog to a home office environment. The experimenters placed a measuring device about six meters from the 3D printers. That measurement device was capable of counting the number of ultrafine particles over a period of time.

Ultrafine particles are extremely small plastic, metal, or organic (in this case plastic) particles. UFPs have diameters less than 100nm. The study measured particles as small as 11.5nm. For perspective on that size, most viruses range in size from 20nm to 250nm.

If the model on the left was a common cold virus, one of the smallest types of viruses, the smallest UFPs in the study would be about one third the size.

Are UFPs Dangerous?

As of now, there has not been a study done to examine the health risks specifically for the UFPs emitted by 3D printers. However, UFPs in general have been linked to a variety of health conditions. Without going into too much detail, the issue with UFPs is that they can be readily inhaled. Once you breathe them in, they can be deposited into the lungs. The particles are so small that they can be absorbed into the bloodstream making them very difficult or impossible to remove. They can also cause harm to different cells in the lungs and throughout the body. Ultrafine particles have been linked to increases in blood pressure. UFPs have even been associated with lung cancer.

Can we Filter out UFPs from 3D Printers?

Alright, so now for the crux of this post. The issue with attempting to filter UFPs is their exceptionally small size.

Filters are rated for the smallest size of particles they are able to filter out of the air. For example, the filter in your furnace/air conditioning system is typically rated to filter out particles down to 3um for high quality filters. The filters used in hospital operating rooms can filter particles down to 0.3um.

These filtering capabilities are represented by a rating system called the minimum efficiency reporting value (MERV). The higher the MERV rating, the smaller the minimum particle size the filter is able to remove from the air. So a home air filter will have a MERV rating between one and about nine. Hospitals use filters with MERV ratings between 13 and 16, which can filter out bacteria. Electronics manufacturing cleanrooms use filters with MERV ratings as high as 20.

Even with these super-fine MERV 20 filters the minimum particle size is under 0.3um. 0.3um, or 300nm is about three times larger than the largest UFPs in the 3D printer emissions study, 115nm. In other words, even with these industrial-quality, expensive filters, the UFPs from a hobby 3D printer will pass straight through like water through a sieve. The most concentrated UFP size buckets in the study had particles ten times too small for a MERV 20 filter to remove.

Many 3D printer operators use enclosures with HEPA filters to help remove odors. HEPA filters are a type of air filter that does not have a regulated efficiency in terms of MERV ratings. However, HEPA filters perform similarly to MERV 20 filters, removing almost all particles from the air passing through that are larger than 0.3um. Therefore, HEPA filters are also incapable of removing UFP emissions from 3D printers. The particles from 3D printers are simply far too small for HEPA filters to catch.

What is There to do About 3D Printer UFP Emissions?

So far we’ve learned that, while enclosing and  filtering a 3D printer can help with plastic smells, noise, and improve printing conditions, filters will do absolutely nothing to eliminate ultrafine particle emissions. What is the answer then?

You, a 3D printer user, have a couple good options, some are even free! A simple solution, if your 3D printer supports wireless printing or printing from SD cards, is to move your printer into a different, unoccupied room. In the study, the number of UFPs dropped off to low levels after about two hours following the completion of the test prints. This is a good option because it will reduce the noise and smell of the printer to nothing as well as prevent exposure to UFPs. Also, it costs nothing to simply move your printer.

Even if your 3D printer does not have wireless or SD card capability, you can still adapt it for wireless operating using a Raspberry Pi and software like Astroprint or Octoprint.

Another solution requiring a small investment of money and time, is to enclose the 3D printer and duct the exhaust air outside. This does involve not only building an enclosure, but also installing an exhaust vent into a wall or window of your home or office. However, ventilating the 3D printer enclosure to the outside will also eliminate your exposure to UFPs as long as the venting is designed well.

Yet another possible way to eliminate 3D printer UFP emissions is to remove the 3D printer…and replace it with a different technology. Although further research might reveal other issues with other 3D printing technologies, replacing your FDM 3D printer with a stereolithographic printer will also eliminate UFPs from your environment.

There are a number of stereolithographic printers on the market today; the most well-known being those from FormLabs. These printers use a laser to cure resin into layers, rather than melting and extruding plastic, they may not produce UFPs. Again, however, this has not been studied. Stereolithographic 3D printers cost significantly more than most FDM printers; they start around $2000. So while using stereolithography likely reduces UFP emissions, it is far from the cheapest option.

The Form 2 is a popular 3D printer that uses a UV-curable resin rather than melting plastic to build objects.