Fine particulate and chemical emissions from desktop 3D printers

Fused deposition modeling (FDM) printers, the more common type of desktop 3D printers, emit volatile gases and particulates that may deteriorate indoor air quality. The developed method for characterizing and quantifying emissions from an operating 3D printer measures fine particulate and volatile organic compound (VOC) concentrations over time using an environment controlled testing chamber. All tested printers emitted ultrafine particulates (UFP). Approximately 70% of the particulates released from the printers were less than 50 nm in diameter. Emitted UFPs increased in size over time by coagulating with other particles and condensation of printer-generated vapors. Chemical compositions of the released gases varied depending on the filament material. Volatile chemicals such as styrene and ethylbenzene were released from acrylonitrile butadiene styrene (ABS) filament. Caprolactam, originating from a nylon filament, was a predominant released gas. Though polylactic acid (PLA) filament is thought to be safer since it is biodegradable, PLA still released chemicals such as methyl methacrylate. Acetaldehyde and formaldehyde were released from all the studied filaments. ABS emitted more particles than PLA or nylon filaments. The extrusion nozzle temperature on the printer had the greatest effect on both particles and VOC emissions; the emissions increased as the temperature of the nozzle increased. Depending on the maker of the filaments, the total particle number emissions varied by a factor of 20. Filament colors had minor effects on emissions compared to other parameters studied. Introduction The 3D printer market is estimated to grow at a compound annual rate of 44% [1]. Among diverse 3D printers on the market, fused deposition modeling (FDM) 3D printers are relatively inexpensive and convenient to use, making them accessible to the general public. FDM 3D printers heat a filament to a semi-liquid state and deposit it to build a 3dimensional object by layers [2]. In particular, desktop-sized 3D printers are often used in educational institutions (from primary schools to universities), design offices, libraries, and within homes [3]. Many of these locations have the potential to expose susceptible populations, such as children, to any toxic emissions generated in the printing process. It is known that commercial extrusion processing of thermoplastics generates both particles and volatile organic compounds (VOCs) [4], and some of the thermal decomposition products are recognized to be toxic [5, 6]. FDM 3D printers are potentially hazardous to operate in certain indoor environments. Due to the increasing usage of 3D printers and past experience with laser printer emissions, characterization of 3D printer emissions is necessary to assess human exposure and potential health impacts. A number of studies have recently reported emissions from commercial 3D printers [7, 8, 9, 10, 11], but the use of differing characterization methods make it difficult to compare and contrast factors influencing emissions reported amongst the previous studies. In order to address this limitation and to understand the factors that drive emissions, a standard testing and evaluation method is essential. Consistent characterization of particle emissions according to printer and filament combinations and operation conditions would then be possible and could be provided to consumers when considering purchasing these printers.