Which of the following is NOT a typical humidity measurement?

• A. Lux.
• B. Dew point.
• C. Percent relative humidity.
• D. Absolute humidity.

Answer: (A)

Humidity measurements focus on how much water vapor is in the air. Typical ways to quantify this are dew point, percent relative humidity, and absolute humidity. Lux is not a measure of moisture at all—it gauges light intensity (illuminance). So the option that is not a typical humidity measurement is Lux.

Dew point indicates the temperature at which air becomes saturated and water vapor begins to condense, giving a direct sense of moisture tendency and condensation risk. Percent relative humidity expresses how much moisture is in the air compared with how much it could hold at that temperature, a common measure for comfort and process control. Absolute humidity reflects the actual amount of water vapor per unit volume of air, useful in some technical and industrial contexts.