Check your respirator for a tight seal—these testers help you comply with OSHA guidelines for respiratory protection. Performed at least once a year, fit tests make sure that a respirator is snug against your face and doesn’t leak. These testers use a bitter solution to test whether you can taste or smell it while wearing the respirator. They’re recommended for fit testing half-face respirators being worn near mild hazards. Keep wearing a respirator with the same manufacturer model and size once you pass a fit test, or you’ll need to test again.