A fit test is a method used to select the right size respirator for the user. Fit testing of all negative or positive pressure tight-fitting facepiece respirators is required prior to initial use, whenever a different respirator facepiece is used, and at least annually thereafter. An additional fit test is required whenever there are changes in the user's physical condition that could affect respirator fit (e.g., facial scarring, dental changes, cosmetic surgery, or an obvious change in body weight). The employee must be fit tested with the same make, model, style, and size of respirator that will be used. See frequently asked questions on respiratory protection or the safety and health topics page on respiratory protection.