We believe that this hiearchy has been long overlooked by many engineers. At this point, warnings are a potential solution. When all other techniques cannot eliminate or control a hazard, employees should be given personal protective equipment to prevent injuries and illnesses. When guarding is inadequate, warnings should be used. The design of the warning is more complex than one might think.
Standards give fairly specific detail on the color schemes and layout of the warning.
The actual text of the warning, however, is more difficult to be precise enough - yet not too precise, and simple enough for all users to fully understand the hazard. John Morse, PE, PhD is experienced in the design of warnings, has worked with warnings standards, and has performed research on warning effectiveness.