Relative humidity refers to what aspect of the air?

Relative humidity is defined as the percentage of water vapor present in the air compared to the maximum amount of water vapor the air can hold at a specific temperature. This measurement is crucial because warmer air can hold more moisture than cooler air. Therefore, if the air is saturated with water vapor, the relative humidity would be 100%. This concept is essential in various fields, including medicine, as it impacts patient comfort and the effectiveness of respiratory therapies. Understanding relative humidity helps healthcare providers manage environmental conditions that can affect patients, particularly those with respiratory issues.

Other options refer to different properties of air: the temperature of the air pertains to how hot or cold it is, the amount of oxygen relates to the composition of the air, and air pressure refers to the force exerted by the weight of air molecules. Each of these aspects is important in their own right but does not define relative humidity.