Effectiveness of Colors used on Safety and Health Signs for Communicating Severity of Injury

Signs are used extensively in workplaces and on products to identify hazards and provide instructions for appropriate behavior. A fundamental element of these signs is the signal-word panel located at the top of the sign. The colors and words in this panel are intended to convey information about the hazard identified. One type of hazard information concerns the severity of injury/illness associated with the hazard. The standard of the American National Standards Institute (ANSI) for facility signs uses three severity categories: 1) death or serious injury, 2) minor or moderate injury, and 3) property damage. The standard specifies which signal-word panel format, including color, to use based in part on the severity category. The purpose of this study was to determine if college students associate color with severity. The sample population consisted of 59 students tested in nine small groups. Twelve signs were shown to them in random order. Five of the signs had a color for the background of the signal-word panel. The colors were red, orange, yellow, blue, and gray. The signal word was a nonsense word and the text panel contained repetitions of the letter x in sentence format. Subject rated their impressions of the colors using two ordered rating scales for severity. Results indicated that color had a highly significant effect on severity ratings. Median ratings were generally consistent with the ANSI standard, except for orange. Red rated highest on both scales. Blue and gray rated lowest. Yellow and orange were in between red and blue. According to the ANSI standard, orange should indicate the same severity as red. These results indicated that orange was associated with less severity than red. Apparently, the ANSI standard's use of orange to identify a hazard associated with death or a serious injury is questionable.