A contactless detection test examines how a device produces a detection result when a person breathes out without putting their mouth on the device. If you keep only the result screen, you cannot tell under what conditions that result was produced. For safety managers or quality and technical staff to compare several detection results, they also need to know the distance between the person breathing out and the device, the orientation of the face relative to the device, and where the device was placed.
Here, distance and posture are not just site notes. In a contactless method, the device works with breath moving through the air rather than a sample it collects directly, so these are the conditions that describe the path by which breath reaches the device. These values are therefore not evidence that a given device performs the same at any distance; they are the boundaries that define how far the test result can be interpreted.
Why a single result cannot be compared on its own
A contactless detection result reflects not only the device's response but also how the test participant followed the instructions. Whether the face was turned toward the device, whether the device was at a different height from the person's mouth, and whether the person breathed from the instructed position all change the path the breath took. Even if the screen shows the same result, if these conditions differ, it is hard to say the same situation was repeated.
In particular, a record that notes only the distance as a number is not enough. A distance with the person's face turned to the side and the same distance facing the front of the device do not mean the direction of the breath was also the same. Recording, in words, the reference point for the distance together with the face direction, the height and orientation of the device, and whether the device was handheld or fixed helps with comparison.
Distance and posture are conditions that define the scope of a test
The purpose of recording distance and posture is not to find conditions that produce favorable results. It is to make clear that the result observed in the test is "a result obtained at the recorded distance and posture." If the result later differs in another location or layout, you can first compare whether the geometric conditions of the two tests were the same, rather than jumping to conclusions about differences in the device itself.
This distinction is also needed so that quantitative analyzers and contactless detection are not evaluated in the same way. The confirmed scope of OIML R 126-1:2021 is quantitative analyzers that collect breath through a mouthpiece. So you cannot interpret this document alone as comprehensively validating the results of a contactless detection test. Test conditions should be set within each device's official measurement method and permitted use, and results should be explained only within those conditions.
Also record the surrounding air and the instruction procedure
In a contactless test, it is hard to look at the conditions between the device and the person in isolation. If it is indoors or outdoors, the direction from which wind or ventilation airflow is felt, or a nearby source of airflow changes, the way breath reaches the device can also change. This information is not meant to claim that the environment necessarily changed the result; it is observational evidence you can review when results differ.
You should also write down the instructions given to the test participant and the test sequence. For example, whether the instruction was "stand in front of the device and breathe," whether the same person was asked to try again after one attempt, and what waiting conditions were set between attempts are all part of interpreting the results. It is best not to merge detection results with results where the sample was insufficient or the procedure was not valid, but to record them separately.
| What to record | What to note | What to check when comparing |
|---|---|---|
| Device and test method | Device used, detection mode selected, accessories used with it | Were the device configuration and method the same? |
| Positions of person and device | Reference point for distance, face direction, device height and orientation | Were the conditions for the breath direction the same? |
| Surrounding air and location | Indoors or outdoors, observed ventilation or wind, nearby airflow | Did a difference in location change along with the result? |
| Instructions and results | Instructions given to the participant, order of attempts, screen results such as detected or invalid | Were procedural failures distinguished from detection results? |
The order of interpretation in a hypothetical on-site comparison
For instance, suppose that at the same location, in the morning test the device was fixed in place and participants breathed from the front following instructions, while in the afternoon test the person holding the device stood beside the participant. The observation that there were fewer detection results or more invalid results in the afternoon is not, on its own, enough to conclude that the device performed worse in one of the tests. That is because the relative orientation of the device and face, the device position, and the way instructions were given all changed together.
In this case, a possible action is to confirm whether the device mode actually used in the two tests was the same, and to record the distance reference point, posture, device position, and surrounding airflow for each attempt separately. You can then compare again under conditions that apply the same instructions and layout. The completion criterion is not that the two results become the same, but a state where a third party can tell, from the records alone, under what conditions each result was produced.
How to separate demonstration materials from performance claims
An on-site demonstration can provide material on the positions from which people follow instructions well and whether the device placement fits the flow of foot traffic. But a demonstration at one location does not represent detection performance at every distance, posture, and airflow. Demonstration videos or result tables should also note the instructions given and the device position, which may not be visible in the footage, so that the screen results are not over-interpreted later.
With sufficient records, the order of review when results differ from expectations also becomes clear. First check whether the test method and device configuration were the same, then whether the distance, posture, and layout differed, and then whether the surrounding air and instruction procedure differed. Conditions recorded this way are not decoration for turning contactless detection results into absolute numerical claims; they are the basis for distinguishing the situations the test actually reproduced from those it did not.
