As with any 3D printing material, there are some safety concerns to keep in mind when using PETG indoors. The most important thing to remember is that PETG emits small amounts of fumes when heated, so it's important to ensure that your workspace is well-ventilated. In terms of health risks, the main concern with PETG is that it can release volatile organic compounds (VOCs) when heated. These VOCs can be harmful if inhaled, so it's important to make sure that you're printing in a well-ventilated area. If you're looking for a safer alternative to PETG, PLA might be a good option. PLA doesn't emit any fumes when heated, making it a safer option for indoor printing.