Originally Posted by
Sarfa33
I believe that R&R is trying to describe
Hypoxia. As the ambient temperature increases, the volume of a gas will increase (Boyle's Law). This means that inhaling the same volume of air into your lungs will yield a lower number of o2 molecules actually making it into your bloodstream.
However, I question whether there is really some kind of line at 78 degrees, above which humans will begin to have problems. A 4 degree F (2 degree C) difference (between 78 & 82 F) seems too small to me to really have any kind of a significant effect. I tried to find anything online that referenced such a phenomenon but was unsuccessful.
-S
Yes, but hypoxia is related to the altitude, not caused by temperature. People with respiratory problems may start to experience hypoxia anywhere from 5,000 ft. altitude. For people without respiratory problem hypoxia, or altitude sickness, usually comes at altitude above 10,000 ft. The commercial aircraft we fly are set to cabin atmosphere anywhere between 4,000 ft. - 6,000 ft. altitude.
Denver, CO is located at elevation of 5,280 ft. During summer time high temperature easily reaches mid 80 F. There are many people working outside, such as construction workers, farmers, etc. Do they experience shortness of breath, headache, and anxious feelings? No, they do not. Any healthy people at 6,000 ft. altitude when temperature is in mid to high 80 F typically do not experience such symptoms. There are hundreds of passengers arriving at Denver everyday who are not accustomed to high altitude condition. Do they experience hypoxia during summer time? No they do not.
Blood oxygen level and carbon dioxide level in human blood is a function of binding coefficient with hemoglobin. Hemoglobin molecular in our blood has iron molecular in the center. Oxygen and carbon dioxide binds (secondary bonding, not covalent bonding) with iron center of hemoglobin. How efficient oxygen and hemoglobin can bind determines blood oxygen level. The chemical reaction mechanism study of oxygen and carbon dioxide with iron core of hemoglobin is exactly what us physical biochemist study. Thank you for lecturing me about what biochemist is, R&R.
I appreciate Sarfa33’s comment, but chemist in me just cannot let this go. Boyle’s Law deal with constant temperature situation. Cannot describe variable temperature conditions. To deal with temperature increase we need Ideal Gas Law (PV=nRT).
Sorry, I am not putting you down, Sarfa33. I do appreciate your comment.
Anyway, even FAA does not require pressurization of cabin when aircraft is flown below 10,000 ft. altitude. I often go up to 10,000 ft. altitude on Cessna 182, where this particular aircraft does not have pressed cabin, and not just me but everybody else are just fine.
There is a big, big difference between altitude sickness and crying and whining about the temperature.