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--- australia:sleepnakedat7deg [2025/11/25 23:30] – [The Secret to maintaining warm air to breathe] gary1
+++ australia:sleepnakedat7deg [2025/11/25 23:31] (current) – [The Secret to maintaining warm air to breathe] gary1
@@ Line 55: / Line 55: @@
     * thus each minute, the tent CO<sub>2</sub> levels will increase by 50000 / (2730L x 5L) = 3.66ppm
     *thus time to reach 5000ppm or 0.5% (the max. industrial safe level for prolonged breathing) = 5000/(3.66 x 60min) = 23hrs
-      * **thus in theory, over 12hrs overnight in winter, the CO<sub>2</sub> should only rise to 0.25% or 2500ppm which will not be problematic for healthy people**
+      * **thus in theory, over 12hrs overnight in winter, the CO<sub>2</sub> should only rise to 0.25% or 2500ppm which will not be problematic for healthy people** (it may be problematic for those with COPD or obstructive sleep apnoea who tend to retain high levels of CO<sub>2</sub>)
     *initial oxygen level is 21% and thus after 12hrs, as each molecule of O<sub>2</sub> is converted to a molecule of CO<sub>2</sub>, this will fall by the same amount the CO<sub>2</sub> rises, ie. 2500ppm or 0.25% which will result in **oxygen levels falling to a very safe 20.75%**
   ***obviously, as you increase ventilation to outside air, you not only lose the warm air, but you also get wind chill if not covered up - so ventilation is a delicate balance for comfort**