3M™ FIT TEST SOLUTION, FT-32, BITTER is a bitter-tasting test solution that helps assess the effectiveness of a respirator mask's seal against harmful airborne particles. It is used during a fit test by spraying it into the mask while the wearer performs movements, and if the wearer detects a bitter taste, it indicates that the mask is not sealing properly. It is used in industrial settings to ensure worker safety and compliance with safety regulations.