Emissions of Ultrafine Particles and Volatile Organic Compou
Posted: Mon Feb 01, 2016 2:08 pm
This is a long and complex scientific examination of the situation and I have put the last paragraph below but the whole thing needs to be read for context
this image is posted as an example of the sort of thing in the whole document. the short version is that ABS and Nylon at high temps are bad and PLA is a lot better in a home environment
of course as I type this i am about 4 feet from my printer running a 4 hour ABS print at 228c
http://pubs.acs.org/doi/full/10.1021/acs.est.5b04983
Emissions of Ultrafine Particles and Volatile Organic Compounds from Commercially Available Desktop Three-Dimensional Printers with Multiple Filaments
Parham Azimi†, Dan Zhao†, Claire Pouzet†‡, Neil E. Crain§, and Brent Stephens*†
† Department of Civil, Architectural and Environmental Engineering, Illinois Institute of Technology, Chicago, Illinois 60616, United States
‡ Ecole des Ingénieurs de la Ville de Paris, 80 Rue Rebeval, 75019 Paris, France
§ Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
Environ. Sci. Technol., Article ASAP
DOI: 10.1021/acs.est.5b04983
Publication Date (Web): January 7, 2016
Copyright © 2016 American Chemical Society
ABSTRACT
Previous research has shown that desktop 3D printers can emit large numbers of ultrafine particles (UFPs, particles less than 100 nm) and some hazardous volatile organic compounds (VOCs) during printing, although very few filament and 3D printer combinations have been tested to date. Here we quantify emissions of UFPs and speciated VOCs from five commercially available filament extrusion desktop 3D printers utilizing up to nine different filaments by controlled experiments in a test chamber. Median estimates of time-varying UFP emission rates ranged from ∼108 to ∼1011 min–1 across all tested combinations, varying primarily by filament material and, to a lesser extent, bed temperature. The individual VOCs emitted in the largest quantities included caprolactam from nylon-based and imitation wood and brick filaments (ranging from ∼2 to ∼180 μg/min), styrene from acrylonitrile butadiene styrene (ABS) and high-impact polystyrene (HIPS) filaments (ranging from ∼10 to ∼110 μg/min), and lactide from polylactic acid (PLA) filaments (ranging from ∼4 to ∼5 μg/min). Results from a screening analysis of potential exposure to these products in a typical small office environment suggest caution should be used when operating many of the printer and filament combinations in poorly ventilated spaces or without the aid of combined gas and particle filtration systems.
[img]http://pubs.acs.org/appl/literatum/publ ... _0005.jpeg[/img]
3.5Implications for Human Exposure and Health Effects
Measurements of UFP and individual VOC emission rates presented here have important implications for human exposure and health effects. For example, styrene, which is classified as a possible human carcinogen by the International Agency for Research on Cancer (IARC classification group 2B),(23) was emitted in large amounts by all ABS filaments and the one HIPS filament. Caprolactam was also emitted in large amounts by four of the filaments: nylon, PCTPE, laybrick, and laywood. Although caprolactam is classified as probably not carcinogenic to humans,(24) the California Office of Environmental Health Hazard Assessment (OEHHA) maintains acute, 8-h, and chronic reference exposure levels (RELs) of only 50, 7, and 2.2 μg/m3, respectively.(25) We are not aware of any relevant information regarding the inhalation toxicity of lactide, the primary individual VOC emitted from PLA filaments.
To provide a basis for comparison to regulatory exposure limits and to help understand potential implications for human health, we used these estimates of UFP and individual VOC emission rates to predict steady-state concentrations that would likely result from constant printer operation in a typical small well-mixed office environment. This effort is not meant to serve as a detailed exposure model but rather as a screening analysis for potential health implications. We should also note that this analysis does not take into account proximity effects that could serve to substantially elevate exposures to both UFPs and VOCs in certain microenvironments compared to well-mixed conditions.
Let us assume that one desktop 3D printer operates continuously in a well-mixed 45 m3 furnished and conditioned office space (i.e., the same office space reported by Stephens et al.(7) Let us assume a worst-case scenario in which a single printer has the maximum median UFP and individual VOC emission rates from the findings herein, which include ∼1011 min–1 for UFPs, 183 μg/min for caprolactam, 113 μg/min for styrene, and 5 μg/min for lactide. Let us assume a typical office ventilation rate of 1 h–1,(26) no sorption losses for the three VOCs (likely a conservative estimate),(27, 28) and a typical UFP deposition loss rate constant of 1.3 h–1.(29) Under these conditions, steady-state indoor concentrations of each of these constituents would be elevated to ∼58 000 cm–3 for UFPs, ∼244 μg/m3 for caprolactam, ∼150 μg/m3 for styrene, and ∼6 μg/m3 for lactide.
The predicted caprolactam concentration (244 μg/m3) would exceed all three RELs identified by the California OEHHA,(25) which suggests that although there is considerable uncertainty in this estimate, exposure to caprolactam from desktop 3D printing in a typical office environment with nylon and nylon-based filaments could lead to adverse health outcomes, particularly for susceptible individuals. Acute exposure to high concentrations of caprolactam is known to be “irritating to the eyes and the respiratory tract” and “may cause effects on the central nervous system”, according to the Centers for Disease Control and Prevention (CDC).(30)
The predicted styrene concentration in this configuration (150 μg/m3) would be approximately 20 times higher than the highest styrene concentration measured in commercial buildings in the U.S. EPA BASE study(31) and more than 20 times higher than the average concentration in U.S. residences.(32) There are also reports that suggest exposure to styrene at these concentrations could be problematic for human health. For example, high indoor styrene concentrations have been estimated to yield relatively high lifetime cancer risks in previous studies that assumed typical potency factors,(33) and even moderate styrene concentrations (i.e., greater than only 2 μg/m3) have been associated with elevated risk of pulmonary infections in infants.(34)
Although we are not aware of any regulatory limits for indoor UFP concentrations, an increase in UFP concentrations to ∼58 000 cm–3 would be approximately 10 times higher than what we typically observe in indoor air in our office and laboratory environments and what has been reported as a typical 8-h average indoor concentration in schools.(35) However, it would only be moderately higher than typical time-averaged concentrations in homes(36) but lower than what is often observed in other microenvironments.(37)
Given these findings, we are prompted to make the following recommendations. First, additional measurements should be conducted to more accurately quantify personal exposures to both UFPs and speciated VOCs that account for proximity effects presented by typical 3D printer use patterns. Second, manufacturers should work toward designing low-emitting filament materials and/or printing technologies. Third, 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. This is particularly true for both styrene- and nylon-based filaments, based on data from the relatively large sample of printers and filament combinations evaluated here.
this image is posted as an example of the sort of thing in the whole document. the short version is that ABS and Nylon at high temps are bad and PLA is a lot better in a home environment
of course as I type this i am about 4 feet from my printer running a 4 hour ABS print at 228c
http://pubs.acs.org/doi/full/10.1021/acs.est.5b04983
Emissions of Ultrafine Particles and Volatile Organic Compounds from Commercially Available Desktop Three-Dimensional Printers with Multiple Filaments
Parham Azimi†, Dan Zhao†, Claire Pouzet†‡, Neil E. Crain§, and Brent Stephens*†
† Department of Civil, Architectural and Environmental Engineering, Illinois Institute of Technology, Chicago, Illinois 60616, United States
‡ Ecole des Ingénieurs de la Ville de Paris, 80 Rue Rebeval, 75019 Paris, France
§ Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
Environ. Sci. Technol., Article ASAP
DOI: 10.1021/acs.est.5b04983
Publication Date (Web): January 7, 2016
Copyright © 2016 American Chemical Society
ABSTRACT
Previous research has shown that desktop 3D printers can emit large numbers of ultrafine particles (UFPs, particles less than 100 nm) and some hazardous volatile organic compounds (VOCs) during printing, although very few filament and 3D printer combinations have been tested to date. Here we quantify emissions of UFPs and speciated VOCs from five commercially available filament extrusion desktop 3D printers utilizing up to nine different filaments by controlled experiments in a test chamber. Median estimates of time-varying UFP emission rates ranged from ∼108 to ∼1011 min–1 across all tested combinations, varying primarily by filament material and, to a lesser extent, bed temperature. The individual VOCs emitted in the largest quantities included caprolactam from nylon-based and imitation wood and brick filaments (ranging from ∼2 to ∼180 μg/min), styrene from acrylonitrile butadiene styrene (ABS) and high-impact polystyrene (HIPS) filaments (ranging from ∼10 to ∼110 μg/min), and lactide from polylactic acid (PLA) filaments (ranging from ∼4 to ∼5 μg/min). Results from a screening analysis of potential exposure to these products in a typical small office environment suggest caution should be used when operating many of the printer and filament combinations in poorly ventilated spaces or without the aid of combined gas and particle filtration systems.
[img]http://pubs.acs.org/appl/literatum/publ ... _0005.jpeg[/img]
3.5Implications for Human Exposure and Health Effects
Measurements of UFP and individual VOC emission rates presented here have important implications for human exposure and health effects. For example, styrene, which is classified as a possible human carcinogen by the International Agency for Research on Cancer (IARC classification group 2B),(23) was emitted in large amounts by all ABS filaments and the one HIPS filament. Caprolactam was also emitted in large amounts by four of the filaments: nylon, PCTPE, laybrick, and laywood. Although caprolactam is classified as probably not carcinogenic to humans,(24) the California Office of Environmental Health Hazard Assessment (OEHHA) maintains acute, 8-h, and chronic reference exposure levels (RELs) of only 50, 7, and 2.2 μg/m3, respectively.(25) We are not aware of any relevant information regarding the inhalation toxicity of lactide, the primary individual VOC emitted from PLA filaments.
To provide a basis for comparison to regulatory exposure limits and to help understand potential implications for human health, we used these estimates of UFP and individual VOC emission rates to predict steady-state concentrations that would likely result from constant printer operation in a typical small well-mixed office environment. This effort is not meant to serve as a detailed exposure model but rather as a screening analysis for potential health implications. We should also note that this analysis does not take into account proximity effects that could serve to substantially elevate exposures to both UFPs and VOCs in certain microenvironments compared to well-mixed conditions.
Let us assume that one desktop 3D printer operates continuously in a well-mixed 45 m3 furnished and conditioned office space (i.e., the same office space reported by Stephens et al.(7) Let us assume a worst-case scenario in which a single printer has the maximum median UFP and individual VOC emission rates from the findings herein, which include ∼1011 min–1 for UFPs, 183 μg/min for caprolactam, 113 μg/min for styrene, and 5 μg/min for lactide. Let us assume a typical office ventilation rate of 1 h–1,(26) no sorption losses for the three VOCs (likely a conservative estimate),(27, 28) and a typical UFP deposition loss rate constant of 1.3 h–1.(29) Under these conditions, steady-state indoor concentrations of each of these constituents would be elevated to ∼58 000 cm–3 for UFPs, ∼244 μg/m3 for caprolactam, ∼150 μg/m3 for styrene, and ∼6 μg/m3 for lactide.
The predicted caprolactam concentration (244 μg/m3) would exceed all three RELs identified by the California OEHHA,(25) which suggests that although there is considerable uncertainty in this estimate, exposure to caprolactam from desktop 3D printing in a typical office environment with nylon and nylon-based filaments could lead to adverse health outcomes, particularly for susceptible individuals. Acute exposure to high concentrations of caprolactam is known to be “irritating to the eyes and the respiratory tract” and “may cause effects on the central nervous system”, according to the Centers for Disease Control and Prevention (CDC).(30)
The predicted styrene concentration in this configuration (150 μg/m3) would be approximately 20 times higher than the highest styrene concentration measured in commercial buildings in the U.S. EPA BASE study(31) and more than 20 times higher than the average concentration in U.S. residences.(32) There are also reports that suggest exposure to styrene at these concentrations could be problematic for human health. For example, high indoor styrene concentrations have been estimated to yield relatively high lifetime cancer risks in previous studies that assumed typical potency factors,(33) and even moderate styrene concentrations (i.e., greater than only 2 μg/m3) have been associated with elevated risk of pulmonary infections in infants.(34)
Although we are not aware of any regulatory limits for indoor UFP concentrations, an increase in UFP concentrations to ∼58 000 cm–3 would be approximately 10 times higher than what we typically observe in indoor air in our office and laboratory environments and what has been reported as a typical 8-h average indoor concentration in schools.(35) However, it would only be moderately higher than typical time-averaged concentrations in homes(36) but lower than what is often observed in other microenvironments.(37)
Given these findings, we are prompted to make the following recommendations. First, additional measurements should be conducted to more accurately quantify personal exposures to both UFPs and speciated VOCs that account for proximity effects presented by typical 3D printer use patterns. Second, manufacturers should work toward designing low-emitting filament materials and/or printing technologies. Third, 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. This is particularly true for both styrene- and nylon-based filaments, based on data from the relatively large sample of printers and filament combinations evaluated here.
