https://www.mdpi.com/1660-4601/18/8/4344/htm
Auszug: "As a critical variable, a low blood carbon dioxide level in pregnant women is maintained via an increased respiratory minute volume, stimulated by progesterone [22]. For a pregnant woman and her unborn child, there is a metabolic need for a fetal–maternal carbon dioxide (CO2) gradient. The mother’s blood carbon dioxide level should always be lower than that of the unborn child in order to ensure the diffusion of CO2 from the fetal blood into the maternal circulation via the placenta. Therefore, mask-related phenomena described above (Section 3.1 and Section 3.2), such as the measurable changes in respiratory physiology with increased breathing resistance, increased dead space volume (Figure 3) and the retention of exhaled carbon dioxide (CO2) are of importance. If CO2 is increasingly rebreathed under masks, this manifestation could, even with subliminal carbon dioxide increases, act as a disturbing variable of the fetal–maternal CO2 gradient increasing over time of exposure and, thus, develop clinical relevance, also with regard to a reduced compensation reserve of the expectant mothers [20,22,28]. In a comparative study, 22 pregnant women wearing N95 masks during 20 min of exercise showed significantly higher percutaneous CO2 values, with average PtcCO2 values of 33.3 mmHg compared to 31.3 mmHg than in 22 pregnant women without masks (p = 0.04) [22]. The heat sensation of the expectant mothers was also significantly increased with masks, with p < 0.001 [22]. Accordingly, in another intervention study, researchers demonstrated that breathing through an N95 mask (FFP2 equivalent) impeded gas exchange in 20 pregnant women at rest and during exercise, causing additional stress on their metabolic system [28]. Thus, under an N95 mask, 20 pregnant women showed a decrease in oxygen uptake capacity VO2 of about 14% (statistically significant, p = 0.013) and a decrease in carbon dioxide output capacity VCO2 of about 18% (statistically significant, p = 0.001)."
Kommentar: wer Oximeter Messungen nutzt, kann selbst bewerten wie drastisch solche Zahlen sind. Und ich kann nur wiederholen, dass das alles auch Gründe sind, warum laut Berufsgenossenschaft die Tragezeit stark begrenzt ist.
Dazu kommt noch die Materialeigenschaft bei UV Licht (Sonne), Leuchtstoffröhre und Feuchtigkeit.
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