Tight-fitting respirators require a tight seal between the respirator and the face. A respirator cannot protect someone if it does not fit properly. Fields that require respirator use, make workers agree to periodic fit testing for continued employment. An employee must have their first fit test and again every 12 months. Facial hair, large weight gain or loss, major dental work, or facial surgery can affect the respirator’s effectiveness. In those case, the employer would need a retest. OSHA mandates that work environments dealing with harmful dusts, smokes, or hazardous environments conduct tests for safer workplaces.