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Air Pressure - What Is Going On?


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Hello All,

I have long been convinced that daily variations in air pressure explain variations in the severity of my dysautonomia symptoms.

So, I started going to the web reports posted by my local weather station.

Where I am (midwest) we are getting socked by a low presure front - predictably, I had a bad day today.

So, I'm looking at the altimeter readings, and next to them, is a "sea level (mb)" column, which appears to be a translation into the air pressure equivalent for altitude. (I suspect this going to be really unclear so let me try to rephrase it): The weather station posts information to this effect:

If you were at elevation _____, then the air pressure would ordinarily be at the same level it is now.

Anyway, the issue here is that, we're getting socked with this low presure front, but the Sea level has only gone from 1017 to 1029 since yesterday. That's just 12 feet of different. Now, correct me if I'm wrong, but it seems like I could duplicate that effect just by going up a flight of stairs. Does this makes sense? I am saying that the air presure changes are either A) too small to be causing the variation in how I'm feeling by themselves, or else, B) just moving up or down a flight of stairs should cause air presure variations large enough to cause symptoms.

I am interested in what others have to say about this. I am under the impression that other people, besides myself, have long believed that air pressure by itself can account for a large part of the variation in our symptoms. Now, I don't know what to think.

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If you want to test this, you should log how you feel at the end of the day before you look at the pressure for that day, in order to avoid the placebo effect (or whatever it's called for this sort of thing). And then put the results into a pretty graph, of course.

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I know that as a front is coming through, my joints and bones feel achy and throb - I also remember that before I received my pacemaker, the cardiologist warned me about flying - he said I would be in big trouble if I went up in an airplane - my heart rate would bottom and not come back up......so, there must be something to altitude and air pressures...........

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I absolutely am affected by changing barometric pressure. I personally do better in low pressure systems. But here is what I know...I always feel awful the day the pressure is changing. If it stays the same for several days, my symptoms level out. None of my doctors are at all surprised by this and say all their POTS and EDS patients report this. No good explanation though.

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Since almost anything under the sun can affect POTS (sleep, fluid intake, food, activities, menstrual cycle, stress, exercise, medication list goes on) I'd be inclined to look for another factor rather than such a small change in pressure. On the stairs theory, you'd have to consider the exertion/exercise, which is known to be one of the biggest triggers for POTS.

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I think we need to consider that what sounds like "small changes" in pressure to us, causes major changes in weather patterns around the world. It doesn't take much of a change to literally change the earth's atmosphere, I don't think it's that far-fetched to think that it would affect our bodies similarly.

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  • 6 years later...

Professor Lily has a lesson on barometric pressure:

 

Barometric pressure (air pressure) is the weight of the air above you all the way to the top of the atmosphere.  It is measured by an instrument called a barometer.  The pressure can change from place to place and with time at the same place.  Differences in air pressure are what drives winds.  High pressure is caused by descending air.  It moves down from above, making the pressure experienced at sea level higher than usual.  Low pressure is caused by ascending air.  It rises, which means at the ground the pressure experienced is lower than usual.  When storms and weather fronts pass by, the barometric pressure decreases at first and then increases after it passes.  

Technically, pressure is the amount of potential energy per unit volume.  Barometric pressure is measured in millibars (mb) according to the system of measurement units typically used by scientists.  The "bar" is a unit of pressure, like pascals or pounds per square inch.  Your weather station is converting pressure at the barometer to pressure at sea level ("sea level pressure"). Some weather stations do that.

Here in USA we also see it expressed as "inHg" which means inches of mercury.  The old barometers used a vial full of mercury that was open to the air, and it had a skinny tube pointing up.  The air pressed down on the open vial of mercury and forced it up the skinny tube to a greater or lesser degree depending on the actual air pressure.  Millibars and inches of mercury have different scales, and one can convert between them mathematically.  

So when you see the barometric pressure go from 1017 mb to 1029 mb it means that the air pressure at the location of the barometer increased by 12 millibars.  It does not mean that the pressure at sea level is equal to the average pressure at 1029 meters above sea level.

There is a link between pressure and altitude, but it is not what you thought it might be.  Average air pressure at sea level is 1013.25 mb (29.9212 inHg).  It decreases by about 12 mb for each 100 meters (328 feet) above sea level in the lowermost part of the atmosphere.  At the summit of Mt. Everest (8,844 m, or 29,029 ft) the pressure is about 337 mb.

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