What if my two breath samples didn't match?

The two-sample requirement exists as a reliability check. Two readings that agree closely suggest the instrument is measuring something real. Two that diverge suggest something interfered.

Where the samples fall outside the acceptable range, the analysis turns to why. Mouth alcohol from a burp during the sequence. An instrument issue. An improperly conducted observation period. The pattern of the divergence can point toward the explanation.

There's a second issue people don't anticipate. Providing one adequate sample and then not providing a second — because of a medical condition, because the person doesn't blow hard enough, or because they stop cooperating — can be treated as a refusal. That now carries criminal exposure, not just a suspension.

If you have asthma, COPD, or another respiratory condition, that's relevant to whether an incomplete test reflects refusal or inability.