Some of the results are summarized below and are discussed in the context of other relevant research in the field. Exit sign visible in smoke-free fire Figure 2. Exit sign nearly obscured in smoke. Visibility is greatly reduced by the glare from the overhead luminaire Figure 3. Visibility of 13 different exit signs in smoke.
Visibility is expressed as the minimum quantity of smoke needed to obliterate the sign.
The figure shows that, in general, brighter signs tend to be more visible than dimmer ones. Variability in the data implies that other factors, such as lettering height, spacing between characters, contrast and glare, also come into play. Sign visibility is consistently greater in darkness compared to when the room lights are at emergency lighting levels. The Effect of Smoke Smoke seriously reduces sign visibility. The signs all conformed to code requirements.