Consider all body substances potentially infectious. Standard precautions are based on the concept that all body substances are potentially infectious and that direct contact with them must be avoided. The nurse should wear gloves when contact with body substances not unsoiled articles or intact skin is anticipated because all body substances from all clients are considered potentially infectious, signs on doors are unnecessary. Gloves and gowns are inappropriate when caring for a client in respiratory isolation because they dont prevent transmission of airborne respiratory infections. The nurse should wear a mask as a barrier to such infections.