Qualitative fit testing uses a fit test solution product. Half-mask respirators, like N95s, prefer fit test solution. This is a pass/fail method that uses a person’s sense of taste or smell. It does not measure the amount of leakage. Employers or unions approve fit tests. There are four fit test solutions that are accepted by OSHA Isoamyl acetate, smells like bananas Saccharin, tastes sweet Bitrex, tastes bitter Irritant smoke, causes coughing The fit test solutions serve the same purpose, which is to see if there is a reaction to the irritant. If there is a reaction, no matter what the smell or taste is, it signals to leakage in the respirator. HomElectrical offers respirator parts like Sweet Fit Test Solution that are designed to meet OSHA fit testing requirements for respirators.