It shouldn't really be a surprise as even regular printers pollute your office's air, but now there's confirmation that desktop FDM 3D printers also emit hazardous gases and particles, some of which are classified as possible human carcinogens. To minimize issues, it's probably best to use these devices in rooms with adequate ventilation.
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.