The mixing of dry powder nanomaterials offers the potential for highly concentrated exposure to “free” nanomaterials and precautions should be taken to minimize exposure to high dose rates of the materials. If the hazard of the nanomaterial is high or unknown, very conservative engineering controls should be employed to limit exposure to the nanomaterials. If the hazard of the nanomaterial is low, but it is in a “free” particulate form, controls should be in place in development and manufacturing to limit exposure.