3D printing might be bad for your health, according to a new study by the Illinois Institute of Technology. Imagine that. Melting plastic in your home might be hazardous. According to a paper published in the journal Atmostpheric Environment, the desktop 3D printers on the market can emit a pretty hefty amount of harmful ultrafine particles (UFPs) into the air. Typically a 3D printer will heat up a thermoplastic feedstock, extrude it through a nozzle, then deposit it onto a sort of landing pad where your item is built. Similar processes are known to emit harmful emissions in industrial environments, but the difference here is that in a factory, an operator might be required to wear certain protective gear and there might be better ventilation. In your home? Not so much.Researchers measured the amount of UFPs let out into the air when a commercial printer (the study doesn't specify which brands) creates a small plastic item. And the emission rates were high—about 20 billion particles per minute for a 3D printer working with PLA material at a relatively low temp and upwards of 200 billion/minute for those working at higher temps and with other materials. Researchers compared it to working with a gas or an electric stove in an inclosed space or smoking a cigarette inside.