The bitter sensitivity solution helps in checking that there's a safe respiratory seal. It's used with the 3M FT-30 Fit Test Apparatus to ensure the respirator meets OSHA standards. This solution uses denatonium benzoate to produce a bitter taste. It allows organizations to meet regulatory fit-testing requirements for respirators. This 3M sensitivity solution works with a nebulizer and collar to test the fit of dust masks and respirators.