Some people check their breath alcohol result with a personal breathalyzer on the way to work the morning after a company dinner or before heading home after a gathering. A personal breathalyzer is a device that shows a result based on exhaled breath. If the number on the screen is higher or lower than expected, it is easy to feel the device is wrong, but you cannot conclude from that number alone that it is fine to drive now.
What you need at that moment is not to rush to guess the cause, but to separate what you just measured from what screen you saw. The result screen, the testing process, and the decision about how to get around are separate issues. If you record the screen and the process, questions about using the device can be checked specifically later, and the decision about getting around can be made conservatively, apart from the uncertain situation.
First distinguish the current result from a stored one
If you see an unexpected number, first check whether that screen is the result of the test you just finished or a previous result stored in the device or app. If a date and time are shown, write them down with the number. When viewing records in an app, too, the time of the test and the time you opened the screen may differ, so keep them separate so you don't read a past record as your current state.
Also note the unit next to the number. %BAC, ‰, and mg/L are all notations for alcohol test results, but comparing only the numbers can change their meaning. So it is better to write "number + unit + test time" as one set in your notes. A self-test value is reference information, and confirming the unit does not by itself determine your legal status or whether you can drive.
Record the screen and the testing process like this
The purpose of the record is not to diagnose a device fault yourself. It is to pass on the facts at the time, rather than guesses, when you later compare against the procedure in the user guide or ask the support desk a question. What actually appeared on the screen and the order of your actions help more than an impression like "it's higher than usual."
| What to record | What to note | Why it helps later |
|---|---|---|
| Result screen | Number, unit, time of the test | So you don't mix it up with other units or previous results |
| On-screen messages | Error, incomplete, battery, or inspection alert text | So you don't interpret a failure indication as a low result |
| Testing sequence | The order in which you prepared and proceeded following the user guide | So you can check uncertain parts of the procedure specifically |
| Travel decision | Whether you held off driving and how you chose to get around | So checking the result stays separate from deciding to leave |
If you take a photo of the screen, make sure the result and messages are legible, and check that no unnecessary personal information, such as your name, address, or current location, appears with it. When you make an inquiry, rather than sending all past records at once, it is better to start with what is needed, such as the model name, the result screen in question, the test time, and the message displayed.
Keep thoughts that look like causes separate from facts
Judgments such as "I slept, so the result should be low" or "I feel fine, so there's no problem" are not facts confirmed on the screen. Even if causes come to mind, such as use of household products, what you did before testing, or the device's condition, write "what I confirmed" and "what I think might be the case" separately. That way you won't settle on a particular action or device condition as the cause without evidence.
Consider a hypothetical example. A driver who attended a gathering the previous day tests the next morning, and the result is higher than expected. The observations are "at what time in the morning a result in which unit appeared," "whether there was an error or incomplete message," and "whether the preparation steps in the user guide were followed." By contrast, "the device must be faulty" or "I slept enough, so I should be able to drive" are interpretations that have not been confirmed.
In this case, a possible action is to keep a record of the result screen and the procedure and hold off on driving yourself. If you are unsure about the device's usage procedure, you can compare against the user guide again and prepare the questions you need based on your records. The completion criterion is not getting a lower number, but sorting out that day's travel another way and checking questions about the screen or procedure separately.
Stop retesting in order to change the result
When a result is unexpected, testing repeatedly to find only the lowest value does not make the situation any clearer. If you keep only the number you want from several results, it becomes hard later to trace which screen came first and whether the test finished normally. Even when you think a retest is needed, it should be a process of checking the conditions and order described in that model's guidance, not a process of picking a result.
You can also set in advance the questions that should stop you from driving. Ask in turn: Is what I'm looking at the result I just measured? Did I read the number and unit together? Is it clear whether the test completed normally? Is any part of the procedure uncertain? Am I about to test again to get a lower result? If even one is unclear, it is right to keep technical checks separate from the decision to leave.
Waiting for an answer to your inquiry is not a reason you have to drive yourself. Deciding first on available ways to get around, such as public transit, a taxi, going with someone, or rescheduling, can reduce the urgency around the number. If you share a car with family, you can also agree that "if the result is ambiguous or the testing process is unclear, we don't drive."
Use stored records to review habits, not as permission to drive
The AF-40BT is described as supporting test result storage and smartphone integration. Such features are better suited to looking back at when you tested and in what situations you saw unexpected screens than to allowing departure based on a single result. Looking at the test time, result, and how you chose to get around that day together reduces the tendency to interpret a particular number in isolation.
When reviewing records, it is better to preserve screens that need checking as they are than to keep only favorable-looking results or delete inconvenient ones. However, app records can contain lifestyle information, so when sharing with family or friends, decide whether to show only the result and time in question or the whole record. Questions about the device itself, such as sensor principles and accuracy, storage conditions, and calibration reminders, are separate matters to handle under testing technology and maintenance.
The point at which you should stop when faced with an unexpected self-check result is the moment you want to interpret the number in the direction you prefer. The role of self-check records is to keep the original screen and the actual sequence, turn uncertain results into specific questions, and decide first on getting around without driving.
Note: Self-check results from DATECH products are provided as reference information only. Actual enforcement standards and testing methods may differ by agency and device, so self-check results may differ from enforcement results, and DATECH accepts no responsibility for enforcement results.
