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Evaluation of Exit Signs in Clear and Smoke Conditions (NISTIR 4399)



Belinda L. Collins, Daniel M. Madrzykowski


The present paper provides a short review of the research literature on the visibility of exit signs, directional markings, and emergency lighting. It also presents a study which assessed the visibility of several types of exit signs including conventional and electroluminescent (EL) in both clear and smoky conditions. A two-part evaluation was performed. In the first, signs were measured photometrically in clear conditions with two different photometers in a laboratory to determine their luminance under dark conditions and with an ambient room illuminance of 54 1x (5 fc). Analysis of these data indicated very wide variations in luminance (from about 0.9 to 1350 cd/m2) as a function of sign type. In the second part of the study, the visibility of the signs in both clear conditions and smoke was assessed psychophysically. A total of 21 observers participated in the assessment of visibility. Analysis of the data indicated that overall sign luminance was one of the primary determinants of visibility in smoke conditions, while uniformity was also an important contributor. The data indicated that some EL signs can be effective in clear conditions and in smoke (particularly if their luminance is above about 10 cd/m2). Consideration of the results indicated that somewhat different characteristics of the signs seemed to determine their visibility for clear conditions than smoke, with uniformity (or sign configuration) playing a larger role in clear conditions, and luminance being more critical in smoke. Finally, the data indicated the need for further research in which the effects of color, sign configuraiton, and luminance are varied parametrically.
NIST Interagency/Internal Report (NISTIR) - 4399
Report Number


smoke, color, exits, optical density, egress, lighting equipment, visibility


Collins, B. and Madrzykowski, D. (1990), Evaluation of Exit Signs in Clear and Smoke Conditions (NISTIR 4399), NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed May 19, 2024)


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Created August 1, 1990, Updated November 10, 2018