Exploring Methods for Surveillance of Occupational Exposure from Additive Manufacturing in Four Different Industrial Facilities

Abstract

3D printing, a type of additive manufacturing (AM), is a rapidly expanding field. Some adverse health effects have been associated with exposure to printing emissions, which makes occupational exposure studies important. There is a lack of exposure studies, particularly from printing methods other than material extrusion (ME). The presented study aimed to evaluate measurement methods for exposure assessment in AM environments and to measure exposure and emissions from four different printing methods [powder bed fusion (PBF), material extrusion (ME), material jetting (MJ), and vat photopolymerization] in industry. Structured exposure diaries and volatile organic compound (VOC) sensors were used over a 5-day working week. Personal and stationary VOC samples and real-time particle measurements were taken for 1 day per facility. Personal inhalable and respirable dust samples were taken during PBF and MJ AM. The use of structured exposure diaries in combination with measurement data revealed that comparatively little time is spent on actual printing and the main exposure comes from post-processing tasks. VOC and particle instruments that log for a longer period are a useful tool as they facilitate the identification of work tasks with high emissions, highlight the importance of ventilation and give a more gathered view of variations in exposure. No alarming levels of VOCs or dust were detected during print nor post-processing in these facilities as adequate preventive measures were installed. As there are a few studies reporting negative health effects, it is still important to keep the exposure as low as reasonable.

An explorative study on respiratory health among operators working in polymer additive manufacturing

“…More than 10 times the concentration (180,000-500,000 particles/cm 3 ) was found when measurements were performed close to the source. Broekhuizen et al suggested a nano reference value of 40,000 particles/cm 3 for nanoparticles with a density below 6 g/cm 3 (polymer particles have a density of 1-2 g/cm 3 ), which was exceeded in this study for all FDM and extrusion prints with no encapsulation or filter (23). Other techniques in this study, i.e., VP, PBF, and MJ, had concentrations below 20,000 particles/cm3 (PBF) or even below 5,000 particles/cm3 (VP and MJ), which is in agreement with other studies (24).…”

“…The methods used are described in detail in ref. 3. Briefly, hightime resolution particle emissions were measured using two different condensation particle counters (CPC): P-Trak 8,525 and Condensation Particle Counter 3,007 (TSI Incorporated, Minnesota 55,126 USA).…”

Particle Safety Assessment in Additive Manufacturing: From Exposure Risks to Advanced Toxicology Testing

“…As all work environments, AM work environments are controlled by occupational hygiene regulations to ensure the workers safety. Regarding airborne particles and chemicals, gravimetric or VOC analyzing techniques are today used to ensure that threshold limit values for specific compounds in air are not exceeded ( Ljunggren et al, 2019 ; Runström-Eden et al, 2021 ). However, it has been shown that the gravimetric measurements are not sufficient when assessing exposure-related health risks; mainly because particle sizes vary from 10 nm to 65 µm or larger, and due to different AM work activities entail different emissions and thereby exposure risks.…”

“…This indicates that airborne emissions associated with AM operations are variable, depending on printing and parts handling processes, raw materials, and ventilation characteristics. In addition, Runström-Eden et al (2021) have recently studied particle and VOC emissions from four different printing techniques: L-PBF, material extrusion (ME), MJ, and vat photopolymerization. The most significant emissions of particles in the size range 10 nm to 1 µm were found during ME printing.…”

“…When comparing the different printing techniques, and feedstock materials, MJ had the highest concentration of VOC (3,200 µg/m −3 ). High peak exposures, 18,000–99,000 μg/m 3 , were measured during cleaning of the printer when post-processing printed material ( Runström-Eden et al, 2021 ). Importantly, an increase in VOC was observed in the evening and a decrease in the morning, roughly the same time as the changes in ventilation settings occur.…”