In terms of lighting, what is 'foot-candle' a measure of?

The measure known as a 'foot-candle' quantifies illuminance, which refers to the amount of light that falls on a given surface area. Specifically, one foot-candle is defined as the illuminance produced by one lumen of light spread uniformly over one square foot. This concept is crucial in industrial hygiene and workplace safety, as proper lighting levels can significantly impact worker comfort and productivity.

Understanding illuminance is essential for ensuring that work environments are adequately lit to meet safety standards and regulatory requirements. The emphasis on foot-candles highlights the importance of not just the brightness of a light source, but how effectively that light illuminates surfaces where tasks are performed. This is particularly relevant in settings such as manufacturing, laboratories, and healthcare facilities, where optimal lighting can influence both performance and safety.