Which of the following is a primary aim of conducting a medical evaluation before respirator use?

The primary aim of conducting a medical evaluation before respirator use is to determine the fitness of the employee to use the device. This evaluation assesses whether an individual has any underlying health conditions or physical limitations that could impair their ability to safely and effectively use a respirator. Factors such as lung function, cardiovascular health, and overall physical capability are considered to ensure that the employee is not only willing but also physically capable of wearing a respirator for the duration required, especially in potentially hazardous environments.

Ensuring comfort during use, assessing the need for training, or calculating the appropriate size of the respirator, while important for overall respirator effectiveness and usability, do not directly address health concerns that could arise from wearing this type of personal protective equipment. The medical evaluation is essential for safety, focusing specifically on the individual's health status before any further action related to training or respirator fitting is taken.