Reflect on this

High-visibility clothing, a type of personal protective equipment (PPE), is any clothing worn that has highly reflective properties or a colour that is easily discernible from any background. Yellow waistcoats worn by emergency services are a common example.

Part of the surface of the garment may have retroreflective stripes. This way they become much more visible in the dark for observers near a light source, such as the driver of a car with its headlights on. The pattern of the retroreflecting parts also helps to distinguish between objects and people. Area reflective fabric has proven to be the most effective way of outlining the body, so that drivers can distinguish a human shape at night.
EN 471:2003 is a European Standard for high-visibility clothing. It deals with High-Visibility Specifications.

There are three levels of protection:
Class 1 Class 1 defines the lowest visibility level e.g. High-visibility trousers with two 5 cm reflective bands around each leg. These become Class 3 when worn with a Class 3 jacket.

Class 2 The class 2 defines an intermediary visibility level. Example: vests. Two 5 cm bands of reflective around body or on one 5 cm band around body and braces to both shoulders.

Class 3 The class 3 defines the highest level of visibility. Example jacket with long sleeves, jacket and trouser suit. Two 5 cm bands of reflective tape around the body, arms and braces over both shoulders. Class 3 should be worn when working within 1.2 metres of a Highway with traffic moving in excess of 50 km/h

[Wikipedia]

Under the Personal Protective Equipment at Work Regulations [1992] a company is required to carry out an assessment of whether protective clothing should be provided to employees who are exposed to risks to their safety at work.