A limited study back in 2013 by researchers from the Illinois Institute of Technology and The University of Texas at Austin suggested that ABS and PLA filaments do release some unhealthy particles into the air during 3D printing, but those same researchers are now back with a more comprehensive study. And the results are not very good – when 3D printing certain filaments in confined spaces, high levels of possibly carcinogenic (cancer-causing) particles can be measured in the air. This has become apparent from a study entitled Emissions of Ultrafine Particles and Volatile Organic Compounds from Commercially Available Desktop Three-Dimensional Printers with Multiple Filaments, which has just appeared in the journal Environmental Science & Technology.