| In preparing for emergency evacuations, it’s | | | | but what about their quality of illumination? |
| best to prepare for the worst evacuation | | | | Unless exit signs indicate a shorter maximum |
| conditions possible. Usually, this involves putting in | | | | viewing distance than 75 feet on their surface, UL |
| place controls that help people exit a building as | | | | requires exit signs be visible from at least 100 ft. |
| quickly as possible while experiencing low visibility, | | | | during normal visibility, meaning that exit signs |
| as might result from a fire. Even when people | | | | must burn with a minimum light level of 54 lux. |
| have mentally rehearsed the proper evacuation | | | | Exit signs that exceed 54 lux can provide greater |
| procedures, they typically go into flight mode | | | | visibility when dust or smoke fill the air. Providing |
| when facing a real emergency, abandoning their | | | | clear visibility at 100 ft and beyond during low |
| clear thinking and well rehearsed plans. Add in low | | | | visibility, photoluminescent exit signs exceed the |
| visibility and it’s easy to see how people can | | | | low visibility viewing distance of most Tritium and |
| take significantly longer to escape a building than | | | | incandescent exit signs. The same is true of |
| they planned, if they escape at all. | | | | photoluminescent egress markings versus |
| Properly maintained fire exit signs and egress | | | | reflective egress markings. The less light that |
| markings offer people the best chance to | | | | surrounds a reflective surface, the less light it |
| evacuate buildings in a safe, expedient manner, | | | | reflects. |
| especially during low visibility. There are two basic | | | | A recent field study conducted by the National |
| kinds of illuminated exit signs: electrical | | | | Research Council of Canada, Public Works and |
| (incandescent, LED, compressed fluorescent) and | | | | Government Services Canada and Jalite PLC |
| self-illuminating (Tritium and photoluminescent | | | | demonstrates the effectiveness of PLM material |
| PLM). Similarly, there are two kinds of illuminated | | | | during emergency evacuations. The experiment |
| egress markings: reflective (reflective tape) and | | | | consisted of mock evacuating a large number |
| self-illuminating (photoluminescent/PLM). | | | | people from the upper floors of an office building |
| Incandescent fire exit signs are still the most | | | | and having them evacuate down four separate |
| common exit signs on the market, but while they | | | | stairwells during low visibility, with three stairwells |
| provide sufficient illumination when visibility is low, | | | | containing differing styles of PLM markings and |
| they’re only as dependable as their back-up | | | | one stairwell containing emergency back up |
| batteries and light bulbs, making them an | | | | lighting. The results of the study show that the |
| ineffective choice for emergencies that result | | | | most preferable stairwell across a broad range of |
| from structural shock and falling debris. | | | | criteria was stairwell containing PLM markings. |
| Non-electrical Tritium exit signs avoid this problem, | | | | Unlike emergency lighting, which highly illuminates |
| but their radioactive capsules can end up breaking | | | | some parts of stairwells and leaves other parts in |
| and causing a second emergency. Like Tritium | | | | shadow, generously applied PLM markings offer |
| signs, PLM signs don’t use electricity, but | | | | evacuees a consummate sense of special |
| neither do they contain radioactive material. | | | | awareness, allowing them to descend stairwells |
| They’re 100 percent non-toxic and recyclable, | | | | safely and more efficiently. |