How is illumination defined in terms of measurement?

Illumination is defined as the amount of light incident upon a surface, which is precisely what the correct answer conveys. This definition emphasizes how much light is actually reaching a specific area and is usually measured in lux, which accounts for the intensity of light as it impacts a surface. This is crucial in industrial hygiene as adequate illumination is essential for worker safety and productivity, especially in environments where visibility is crucial for reducing hazards.

The focus on the amount of light striking a surface helps in assessing whether lighting levels meet regulatory requirements and safety standards, directly influencing workplace conditions. Proper illumination is essential for tasks requiring attention to detail, enhancing visibility, and reducing the risk of accidents.

In contrast, the total light output from a source relates to the light emitted but does not consider how much of that light actually reaches surfaces or contributes to illumination. Light intensity per area discusses how focused or diffuse light can be, but does not specifically address the quantity of light available at a surface level. Lastly, brightness as perceived by the human eye is subjective and can vary from person to person, making it less reliable in terms of objective measurement needed for industrial applications.