Evaluation of the Maximum Cognitive Distance Per Emergency Exit Sign Colour in a Smoke-Filled Environment Simulated Using a Translucent Eye Patch

Abstract

Exit signs are intended to help occupants promptly and accurately select evacuation paths during emergencies. However, according to previous studies and accident cases, exit signs are not helpful for occupants during emergency situations, which can be attributed to limited visibility due to the smoke generated during fires. Further, most exit sign installation standards do not consider exit sign visibility in smoke-filled environments. Thus, exit sign visibility can be considered to be low during actual fires. To overcome this issue, a means of improving visibility was investigated in this study by changing the exit sign color. A full-scale experiment was conducted to analyse the maximum cognitive distance (The maximum cognitive distance is defined as the greatest distance at which an observer can clearly identify the content of an exit sign) according to the exit sign safety colour in which a smoke-filled environment was simulated using a translucent eye patch. The smoke-filled environment was divided into nine levels of obstructed visibility according to the visibility distance when a translucent eye patch was worn. The maximum cognitive distance was measured for exit signs in seven safety colours (red, orange, yellow, green, blue, navy, and purple). The results showed that the mean maximum cognitive distances of the navy, purple, blue, and red exit signs were greater than that of the green exit sign, which is widely used currently. The navy, purple, blue, and red exit signs had mean maximum cognitive distances approximately 1.29 times, 1.23 times, 1.22 times, and 1.21 times longer than that of the green exit sign, respectively. The differences in the mean maximum cognitive distance were found to be statistically significant at a level of 0.05. This study’s analysis showed that these four colours had a greater contrast effect on the background colour (white) than green. Hence, the contrast difference between the safety colour and the background colour is considered the main parameter affecting cognitive performance for the exit sign lighting.