Jose Maria Bea said some 10 prostitutes at a highway roundabout near Els Alamus began donning the phosphorescent green garments this month after police started fining them 40 euros ($A56.80).
That's the amount anyone in Spain can be fined for standing or walking along a highway, such as during a vehicle breakdown, for not wearing the high-visibility vest.
Bea said it was dangerous for both the women and motorists if the prostitutes couldn't be seen clearly.
Sex is a huge industry in Spain. Pimping is illegal but prostitution is not, although some cities restrict or ban it in public areas.
