## 4 Discussion
TEWL values are not only influenced by environmental conditions, but even by environmental pollution. It is assumed that damage caused by free radicals in the context of environmental pollution leads to an increase in measured TEWL values [49]. Another comprehensive study analyzed 33 studies for possible confounding variables, factors that could influence TEWL measurement. Twelve variables could be summarized, including factors such as wearing a mask and vascular diseases, but also age and weight. Since many of these factors cannot be controlled in clinical studies, the authors even go so far as to say that the definition of a \"normal\" TEWL value is not trivial or even impossible [27]. Overall, there is already a lot of literature on supposedly impure TEWL measurements. However, a comparison of 22 different measuring devices in a total of 38 studies showed that different devices achieve similar TEWL results. The results obtained are therefore far from random [50]. Nonetheless, there is a non-negligible susceptibility to error and confounding variables. A comprehensive study compared a total of 19 studies that provided data on the hydration of the stratum corneum. It was clearly shown that the hydration values of the skin depend on the respective localization. In the study, the lowest hydration values were found for the back of the test subjects and the highest for the face [51]. In the present study, TEWL and skin hydration were measured exclusively on the back of the test subjects, with randomization. A further investigation that also includes other parts of the body could provide additional groundbreaking findings. On the other hand, the area to be examined could also be limited even further. This is because the localization-dependent measurement differences are prevalent, even within the \"back\" area. For example, an almost linear increase in the skin moisture of the back could be determined from back areas at the level of the hip region up to the skin of the neck [52]. As the area of the back where the crossbar of the bra underwire runs was omitted in the present study, in order to avoid premature detachment of the dressings, no measurements could be carried out in the corresponding skin area. A follow-up study with an equal sample size of male and female participants could investigate whether this circumstance has a significant influence on the data collected. The Corneometer CM 820 (@Courage & Khazaka) was used in the present study. In a study by [PERSON] et al., it was shown that the measuring probe provides reliable results that are comparable with other manufacturers' devices [53]. Nevertheless, even more accurate measurements could be obtained for the MoistureMeter SC-2 (Delfin Technologies Ltd., Kuopio, Finland) [53]. Future comparative studies with other manufacturers' devices could confirm the results obtained. In summary, it can be said that the imitations of the study concern the following aspects: inter-individual differences in measurement could contribute to biased effects. The TEWL value is very susceptible to interference, and depends on many factors. Not all of these factors can be adequately controlled. For financial and economic reasons, not all categories of wound dressings available on the market could be investigated (e.g., newer bioengineering approaches). In addition, the number of test subjects had to be limited. Based on our experience with the measuring device, a total of 20 test subjects had been estimated as adequate for the experiments. Further studies could build on these findings and expand our knowledge on the complex field of wound dressings.