An anonymous reader writes: A new study in the journal Environmental Science & Technology by researchers at Illinois Institute of Technology and The University of Texas at Austin sheds more light on potentially harmful emissions from desktop FDM 3D printers. The researchers measured emissions of both ultrafine particles (UFPs) and volatile organic compounds (VOCs) from 5 commercially available polymer-extrusion 3D printers using up to 9 different filaments. [The researchers] found that the individual VOCs emitted in the largest quantities included caprolactam from nylon-based and imitation wood and brick filaments (ranging from ~2 to ~180 g/min), styrene from acrylonitrile butadiene styrene (ABS) and high-impact polystyrene (HIPS) filaments (ranging from ~10 to ~110 g/min), and lactide from polylactic acid (PLA) filaments (ranging from ~4 to ~5 g/min). Styrene is classified as a "possible human carcinogen" by the International Agency for Research on Cancer (IARC classification group 2B). While caprolactam is classified as "probably not carcinogenic to humans," the California Office of Environmental Health Hazard Assessment (OEHHA) maintains low acute, 8-hour, and chronic reference exposure levels (RELs) of only 50, 7, and 2.2 g per cubic meters, respectively, all of which would likely be exceeded with just one of the higher emitting printers operating in a small office.