High-visibility safety apparel (HVS) is crucial in increasing workers' visibility and safety in hazardous environments. CSA standard Z66 - High-visibility safety apparel sets out specific requirements for such garments, defining criteria for colour, retro-reflectivity, minimum surface areas, and the configuration and visual performance of the materials used. The standard also defines test methods to ensure minimum visibility, even after regular garment maintenance.

The body surface determines the classification of high-visibility safety clothing it covers. Three classes have been established, with classes 2 and 3 being the most sought-after on the job market.

• Class 2: Covering some areas of the body, it offers excellent visibility.
• Class 3: Covering the largest surface area of the body, it ensures the best visibility, particularly in low-light conditions or at a distance.

In addition, retroreflective materials are essential in reflecting light directly back to its source. This characteristic is particularly effective in low-light conditions, offering enhanced visibility. The two most common levels of retroreflection are :

• Level 1: Offering high retroreflective performance, ensuring visibility in darkness over medium distances.
• Level 2: Provides the highest retroreflective performance, guaranteeing visibility in the dark over long distances.

High-visibility safety clothing, conforming to defined standards, is important for keeping workers safe in environments where visibility is crucial.