The Personal Protective Equipment Regulations 2002

PPE in the form of clothing capable of signalling the user’s presence visually

2.13.  PPE in the form of clothing intended for foreseeable conditions of use in which the user’s presence must be visibly and individually signalled must have one (or more) judiciously positioned means of or devices for emitting direct or reflected visible radiation of appropriate luminous intensity and photometric and colorimetric properties.