The United Kingdom’s (UK) Health and Safety Executive (HSE) has posted a guidance document describing how to control occupational exposure to manufactured nanomaterials in the workplace. HSE intends the guidance to assist in compliance with the Control of Substances Hazardous to Health Regulations 2002 (COSHH) (as amended). HSE states that the guidance is specifically about the manufacture and manipulation of all manufactured nanomaterials, carbon nanotubes (CNT), and other bio-persistent high aspect ratio nanomaterials (HARN). HSE prepared the guidance “in response to emerging evidence about the toxicity of these materials.” According to HSE, the control principles described in the guidance can be applied to all nanomaterials used in the workplace. HSE highlights any differences in the approach between control of CNTs and other bio-persistent HARNs to other types of nanomaterials.