Exit signs and emergency lights help people escape during an emergency or power outage. Exit signs and emergency lights help guide people to exits when they are unfamiliar with the area or panicked, or have impaired vision.

Measuring the intensity of light in a space is accomplished by evaluating how much light falls within a single square foot (or square meter) of floor space. The light level measured in a single square foot of floor space is referred to as a footcandle, while a Lumen/Lux measures the light intensity within a single square meter of floor space. Common light metering equipment is used to determine the lighting level in an area of floor space.