Conspicuity refers to how easily an object attracts visual attention. 

Reflective clothing must be highly visible to alert others to the presence of the wearer in high-risk situations. The EN ISO 20471 standard classifies reflective clothing for professional use into three categories based on the minimum areas of retroreflective material, background material, and/or combined-performance material. 

Employers, in consultation with the user, should select the appropriate class and design of clothing based on a risk assessment for the specific location and situation where protective reflective clothing is needed. This assessment should consider factors that may affect an observer's ability to notice the person. 

Observers must be able to perceive and recognize the wearer and react appropriately to avoid potential hazards. It's important to understand that wearing a high-visibility garment does not guarantee that the wearer will be visible in all conditions.