[Bored chemist]

OK, I screwed up about the temp/RH data.
From the point of view of the effect on illnesss- it doesn't matter. It just means that an illness associated with high RH might prefer high temperatures.
There's still no direct evidence that correlation implies causation. Temperature is still a confounding variable (just in the oposite sense to that which I first said).
Here's another possible confounding variable; if the weather is good you dry stuff outside. If the weather is poor you dry stuff on the radiators (and keep the windows closed) so the RH rises.
It could be that the relapses were related to the weather, and that the changes in RH were a consequence of the weather too.

The warmest air in this room at the moment is the stuff in my lungs- it's also the wettest.
Lungs lose water to the air that goes in and out of them.

Also, the humidity is, as you say, dependent on the partial pressure of the water present. And, by Dalton's law that is independent of the absolute presssure. The vapour pressure of water is also independent of the air pressure.
Relative humididty is still perfectly well defined in the absense of air.

[LeeE]

Agreed.

I think the only thing I'd flag for further clarification would the be issue of 'illnesses'.  To discuss it properly we'd need to clarify whether we're talking about effects of weather upon existing conditions or the effects of weather upon contracting a new illness or condition.

That would be a report though, not a response.

[Andrew K Fletcher]

Pauline Phelps, a lady with ms who has been helped by sleeping on an inclined bed, found that some mornings her dropped foot would be a problem. Dropped foot happens when the nervous system is compromised between the foot and the brain, in ms it is thought to be caused by plaques in the myelin sheath around the nerves. Yet Pauline began to record the humidity using a simple meter provided by yours truly. Having done so higher humidity appeared to be indicative so a dehumidifier was introduced into her bedroom during the night and additional water was drank to replace the additional lost fluids from the respiratory tract and skin. In the mornings when the dehumidifier was used during the night her dropped foot problem was not present, yet during high humidity weather when the dehumidifier was not used or had switched off when full her dropped foot problem became apparent again.

Pauline’s experiments with the dehumidifier proved beyond any doubt that humidity plays a very important part in ms. And because Pauline was asleep when the experiment was performed we can eliminate placebo as a cause of her improvements or demise.

[lyner]

But she hasn't drowned yet?
Wearing a life jacket on an inclined bed could be uncomfortable. LOL

[LeeE]

Andrew, what you say is interesting, but the health issues thing is a bit OT in this thread, not that I've been innocent in referring to to it either.

Briefly though, the correlation seems clear but need be trialled on a wider scale.  There would seem to be little risk in such a trial and it wouldn't seem to be very expensive to conduct either, so I'd suggest that you and your friend get together and ask your doctor about the best medical body to approach with your findings, with a view to conducting wider scale trials.

[Bored chemist]

"And because Pauline was asleep when the experiment was performed we can eliminate placebo as a cause of her improvements or demise."
Two things- you need to look up the meaning of the word "demise" and also, as she was awake when she made the observation of her condition it may well have been affected by the placebo effect.
Anyway,as I said, the correlation does not imply causation.
Just for the record this "and additional water was drank " is what we call a confounding variable. If you plan to do a proper trial you need to avoid that sort of thing.

[tuttut]

Andrew k fletcher:
why didn't you mention Pauline before when you gave some rather wushu washy examples to make your point? It look a bit dubious.
What instrument did you supply her with? What times of day did she rcord the RH? Do you understand the times of day when RH is generally going to be low or high?

[geldoon]

I know this thread is 5 years old but I just had to put in my two cents. I'm from Queensland and we often have days like today with a 32 degree heat and 87% humidity. We also get fog in the warm months and the cold, by cold I mean relatively around 20 degrees. Winter is almost always dry. Just look at some film of the jungles of Bornea blanketed in fog and it's warmer there than here. I hope someone reads this or I'm just talking to myself lol.   []

[chiralSPO]

If the environmental temperature is higher than body temperature, and the humidity is high enough that the dew point is body temp or above, then water will condense in your lungs and you will drown. This is a pretty rare scenario, but is the case for crystal cave, Mexico.(http://ngm.nationalgeographic.com/2008/11/crystal-giants/shea-text

Under these conditions, hyperthermia is also a serious risk, but the humidity will kill you faster unless you bring some equipment to breath...

[dlorde]

High humidity indoors (e.g. from drying washing) is said to pose a potential risk of fungal lung infections for immune compromised or asthmatic individuals.

[cheryl j]

https://answers.yahoo.com/question/index?qid=20070715183613AANoYqb

The person above calculate the humidity in lungs at 87.9%. Wikipedia says "In addition to removing carbon dioxide, breathing results in loss of water from the body. Exhaled air has a relative humidity of 100% because of water diffusing across the moist surface of breathing passages and alveoli. When a person exhales into very cold outdoor air, the moisture-laden atmosphere from the lungs becomes chilled to the point where the water condenses into a fog, making the exhale visible."

Mucous membranes of the upper respiratory tract add consider moisture to inhaled air, since usually the problem is the opposite - air is much too cold and dry for the delicate alveoli in the lungs. In high humidity, I would think mucous cells would simply respond by not secreting as much.

I do see articles about the effect of high humidity on asthma and other types of COPD, but that would be for patients who may not have normal response in the membranes of the respiratory tract and bronchi, and with emphysema, they would have differences in the shape and number of airsacs and elasticity of the lungs.

But for normal people, high humidity shouldn't be a big problem as far as "drowning", As far as infectious diseases, you'd have to separate the effects of humidity on the overall survival or transmission of the organism in the environment, as opposed to its growth because of higher than normal humidity once it gets inside the lungs.

[alancalverd]

Humidity of 87% or whatever does not mean that you are breathing 87% water!

The number we use is relative humidity (RH), i.e. the ratio of the actual water content to the maximum amount that air can hold at a given temperature (saturation value). The saturation value is about 1 - 2% by weight (more at higher temperatures). 

No chance of drowning in 100% RH since the surface of the lungs is covered with water anyway, but if the humidity and temperature are high you will be less able to excrete water by exhalation so breathing may become uncomfortable - as in a steam room. I'm pretty sure the body acclimatises and diverts excretion to the bladder - I hope so, as I live in a foggy country!