It depend on your state's policy, there are many standard for reflective vest or uniform for workers, like ANSI/ISEA 107 or EN ISO 20471 , you can ask the local administration about the standard or calss they require and then chose the porper reflective clothing.

Yes it is, reflective material is design for outdoor activity in low visible condition, in daytime when sunlight is enough is looks grey color, but in night it can reflective light and seem shining, reflective tint is chemical characteristic but reflective fabric or heatransfer pattern( you can see it in many reflective vest or traffic police uniform) reflect because physical principles?it's harmless and widly used.