Comprehensive Guide on 3D Printers, UFP Emissions, and HEPA Filtration: Protect Your Health

Nowadays, it is a common sight to see 3D printers in homes, schools, offices, labs, and workshops. The ability to quickly and economically print objects and prototypes make 3D printing one of the fastest-growing technologies today. The process of creating three-dimensional printed objects is actually quite interesting.

3D printing is revolutionizing various industries, from manufacturing to education. However, the process also emits ultrafine particles (UFPs) that can pose significant health risks.  This article explores the dangers of UFP emissions from 3D printers and the role of HEPA filtration in mitigating these risks.

What is 3D Printing?

The majority of commercially available 3D printers utilize an additive manufacturing technique known as molten polymer deposition (MPD), whereby a solid thermoplastic filament is forced through a computer-driven extrusion nozzle. The heated nozzle melts the thermoplastic feedstock and deposits streams of extruded plastic in thin layers across a moving baseplate. As the material hardens and the base plate moves to the next layer, the three-dimensional solid shape is rapidly formed. 

Ultrafine Particles (UFPs) in 3D Printing

UFPs are particles less than 100 nanometers in diameter, released during the heating and extrusion of thermoplastic filaments. These particles are concerning because they can penetrate deep into the lungs and enter the bloodstream, potentially causing respiratory and cardiovascular issues.

Hazards of 3D Printing

While 3D printing is a fun and exciting new technology, the basics of melting plastic to reform it into something new is an old processing technique. It should be noted here that several health and safety agencies, as well as independent researchers, have spent years studying the process of plastic thermal degradation and their subsequent health effects.

Only in the past few years have studies focused on plastic decomposition as it relates to 3D printing. Their findings are important in that measurable respiratory hazards are emitted during the 3D printing process and greater research should be done on this topic.

• Many desktop 3D printers rely on heated thermoplastic extrusion and deposition, which is a process that has been shown to have significant aerosol emissions in industrial environments. (Stephens, Azimi, Orch, Ramos 2013)

While this article focuses on plastic-based 3D printing filaments and their associated health effects, we have included a sampling of other materials used in 3D printing. Limited research, if any, has been done on non-plastic-based filaments. However, similar precautions outlined in this article should be implemented when working with any type of 3D filament.

Examples of 3D printing filaments

Acrylonitrile Butadiene Styrene (ABS)*	Nylon	Polyvinyl Acetate (PVA)	Plasticized Copolyamide TPE (PCTPE)
Polylactide Resin (PLA)*	Polycarbonate (PC)	High Density Polyethylene (HDPE)	Other polymers, metals, ceramics

*Most popular filaments

Chemical Health Hazards of Popular 3D Printing Filaments 

ABS Filament

Comprised of three primary chemicals: acrylonitrile, butadiene, and styrene, ABS is one of the most popular filaments for 3D printing. Because of the popularity of this filament, it is important to discuss the studied properties, characteristics, and health effects involved when ABS undergoes thermal processing and decomposition.

To begin, all three of these components are listed as carcinogenic or possibly carcinogenic to humans according to the International Agency for Research on Cancer (IARC)

• Acrylonitrile – Possibly carcinogenic to humans
• Butadiene – Carcinogenic to humans
• Styrene – Possibly carcinogenic to humans

When exposed to melting temperatures, ABS polymers will begin to breakdown and one study identified up to 27 chemical compounds generated as a byproduct of ABS combustion.

• In the case of ABS, twenty-seven chemical compounds have been identified as combustion products. It is obvious that more combustion products are generated, but have not been identified or investigated to date. The degradation products which appear to be of primary toxicologic concern are CO and HCN. 

What is particularly concerning about ABS decomposition is the quantity of styrene emitted. A 2016 study of ultrafine particle (UFP) emissions for multiple 3D printer and filament combinations found that the primary VOC emitted from ABS filament is styrene.

• The predicted styrene concentration in this configuration would be approximately 20 times higher than the highest styrene concentration measure in a commercial building in the US EPA BASE study and more than 20 times higher than the average concentration in US residences. There are also reports that suggest exposure to styrene at these concentrations could be problematic for human health. 

Due to the negative health effects of styrene exposure, OSHA has placed strict limits on the permissible exposure level to workers. NIOSH recommends even further reduction in the exposure limits.

STYRENE EXPOSURE
Agency	Exposure Limit	Side Effects
OSHA Permissible Exposure Limit	TWA 100 ppm Ceiling 200 ppm STEL 600 ppm	Health effects from exposure to styrene may involve the central nervous system and include complaints of headache, fatigue, dizziness, confusion, drowsiness, malaise, difficulty in concentrating, and a feeling of intoxication
NIOSH Recommended Exposure Limit	TWA 50 ppm STEL 100 ppm

PLA Filament

Polylactic Acid (PLA) is another thermoplastic that is widely used in 3D printing. While there is currently limited health and safety information regarding thermally-decomposed PLA, studies have shown that the thermoplastic still emits measurable amounts of ultrafine particles.

• The operation of the two printers utilizing PLA as a feedstock increased concentrations primarily for particles larger than 20 nm.

However, in the same study researchers found that ABS filament emitted much higher levels of UFP than its PLA counterpart.

• The higher temperature ABS-based printers had total UFP emission rates nearly an order of magnitude higher than the lower temperature PLA-based printers. Peak emission rates from the PLA-based printers occurred in the 48-65 nm size range while peak emission rates from the higher temperature ABS-based printers occurred in a smaller size range (~15-49 nm). (Stephens, Azimi, Orch, Ramos 2013)

While PLA may be a better alternative to ABS in regards to ultrafine particles emission, caution should still be used to avoid overexposure.

Health Hazards of Ultrafine Particles (UFP)

Gases, fume, and ultrafine particles are all emitted during the 3D printing process due to the melting of the printer’s filament. While any type of emission may pose health risks, researchers are particularly concerned with ultrafine particles.

• Moreover, ultrafine particles may be of particular importance for toxicity and fumes emitted from the melting of some thermoplastics 

A 2016 study of commercially available 3D printers sought to measure both the size and quantity of UFP emitted during the printing process. Researchers found that UFP levels spiked during particular printing time intervals.

• Results are similar to results from most of the experiments in that UFP concentrations typically rapidly increased just after printing began and persisted for the first 10-20 minutes, then decreased to a lower level, albeit typically to a level that was still higher than the background concentration. During some tests with other printer and filament combinations, UFP concentrations peaked again near the end of the print period as the thin protrusions on the printed object were created.

In 2013, a review panel from the Health Effects Institute (HEI) published an extensive report on UFP entitled: Understanding the Health Effects of Ambient Ultrafine Particles. In their report, HEI noted the unique health risks UFP pose when compared to larger particles.

• Experimental studies have provided evidence to indicate that, as a result of their physical characteristics, inhaled UFPs differ from larger particles in their deposition patterns in the lung, their clearance mechanisms, and in their potential for translocation from the lung to other tissues in the body. Some animal studies have also demonstrated translocation of UFPs via the olfactory nerve to the brain. Taken together, these findings provide a rationale for the hypothesis that the adverse health effects of exposure to UFPs differ from those of larger particles

Furthermore, “Observed effects in selected studies include lung function changes, airway inflammation, enhanced allergic responses, vascular thrombogenic effects, altered endothelial function, altered heart rate and heart rate variability, accelerated atherosclerosis, and increased markers of brain inflammation.”

In a joint effort study, researchers Merlo and Mazzoni partnered with WASP Project by CSP Sri to deepen their understanding of 3D printing health hazards in terms of healthiness in the workplace. In their report, they detail how nanoparticles travel through the human body. 

• Recent studies have highlighted how nanoparticles are able to enter into human blood system in less than a minute. Once absorbed in the respiratory tract, skin and gastrointestinal tract, the particles may reach the systemic circulation and migrate successfully in different organs and tissues; in particular the organs that appear to be most vulnerable are the liver and the spleen, which perform a job of filtering toxic substances in the human body, aggravating their functionality. 

Additionally, “Various studies have shown that these diseases are related to oxidative stress caused by emissions of toxic substances that affect human cells accelerating their aging.” 

How to prevent exposure to ultrafine particles and fumes from 3D printing

• Given these findings, we are prompted to make the following recommendations in the absence of new low-emitting filaments, manufacturers should work to evaluate the effectiveness of sealed enclosures on both UFP and VOC emissions or to introduce combined gas and particle filtration systems. Until then, we continue to suggest that caution should be used when operating many printer and filament combinations in enclosed or poorly ventilated spaces or without the aid of gas and particle filtration systems. (Azimi, Zhao, Pouzet, Crain, Stephens 2016)

• Long before the final conclusions of toxicology research studies, it is today necessary to apply the principle of precaution by implementing among other, efficient personal protections against the engineered nanoparticles in order to decrease the exposure Among all the tested filters the HEPA cellulose filter used in nuclear monitoring, the HEPA H14 and the ULPA U15, showed the best efficiency for smaller particles. – (Golanski, Guiot, Rouillon, Pocachard, Tardif 2009)

• In this work, we present some of the first known measurements of which we are aware of UFP emissions from commercially available desktop 3D printers These results suggest caution should be used when operating some commercially available 3D printers in unvented or inadequately filtered indoor environments. – (Stephens, Azimi, Orch, Ramos 2013)

• So far it is already possible to give some tips and suggestions, such as using the printers in ventilated places, even better if provided with an air exchange system with a primary power of at least 3 volumes of the room per hour. (Merlo, Mazzoni)

HEPA and ULPA Filtration for UFP

Larger particles (pollen, dust, spores, etc.) are measured in microns (micrometers). One micron is one-millionth of a meter and is expressed as millimeter or µm. Smaller particles that cannot be measured in the micron-scale often referred to as ultrafine particles (UFP), are measured in nanometers. One nanometer is one-billionth of a meter and is expressed as nm.

Historically, HEPA and ULPA filters are known to be excellent media for the capture of particles. While there are several types of HEPA and ULPA filters based on relative efficiency levels, the most common efficiencies used in industry are as follows:

• HEPA – Up to 99.97% efficient on particles down to 0.3 microns

• ULPA – Up to 99.9995% efficient on particles down to 0.12 microns

To better understand HEPA and ULPA filtration efficiencies, the below chart illustrates common particle sizes on the micron scale.

3D Printing Fume and Particle Control Solutions

Several studies cited in this article mention particulate and/or gas filters for controlling UFPs and VOCs. The use of engineered safety controls during 3D printing will have a significant impact on reducing exposure to these emissions. Fumeclear® has been designing and manufacturing air filtration systems for over 30 years. Our products are available with either HEPA or granular activated carbon filters, or a combination of multiple filter types. Because our product designs are modular, we are able to accommodate all types of 3D printers, large or small, open or closed printer beds.

For more information on Fumeclear® 3D printing fume control solutions, visit our website. We have application experts ready to discuss your 3D application and work with you to find the most economical and effective solution.

Contact Fumeclear®

To learn more about engineered safety controls for 3D printing operations or to get a free quote, contact Fumeclear® on WhatsApp +86 18927425235, email support@fumeclear.com, visit our website or fill out our contact form.