I take a lot of hot showers, and sometimes I find myself wondering why I am able to breathe in the steam around me and not worry about any water-in-lungs related health concerns. How is breathing in steam different than breathing in small amounts of water droplets?
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The key difference is that gaseous water vapor does not block oxygen from reaching the blood vessels or carbon dioxide from escaping from them. Liquid water will form a layer over the blood vessels, keeping them from exchanging gases properly. This is the difference between a liquid and a gas.
Trace amounts of liquid water won’t cause issues either, between it not blocking enough vessel surface area and getting fairly absorbed into the body. Roughly speaking, you need about 1 ml of liquid water in the lungs per kg you weigh, putting an average adult at around ¼ cup/60 ml needed to drown. The exact amount will vary from person to person and incident to incident, and I strongly do not recommend testing it yourself.
Water vapor can theoretically condense in the lungs, but will only do so in any quantity once the temperature drops below the dew point. Practically, for this to occur in the lungs, the air temperature would need to be higher than body temperature with extremely high humidity. This would be absolutely miserable to be in: the heat index would be at least 188F/87C – for comparison, a hot sauna is generally no higher than 175F/80C.
Water is always in your lungs. A tiny bit more won’t hurt. So long as you don’t add enough to significantly change the water content of the lungs it’s no trouble at all.
Think about all of the water you breathe out. That’s all water that was in your lungs and evaporated.
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Be aware that when you see a misty cloud around hot water, like a kettle or shower, the thing that you’re seeing is *not* steam but tiny drops of liquid water. Hot water does produce steam but, released into the air, it quickly cools and so turns back into liquid. Even your warm lungs can add their water to the air and, in cold weather, you can see this condensing as you breathe out.
There is steam (AKA water vapor) in the air but you generally can’t see it. On a warm humid day the air you’re breathing can be 3% steam.
Basically, it’s because water getting in your lungs isn’t a problem
Your lungs are already made of, and filled with water. A little bit of vapour isn’t changing anything
The only reason too much liquid water in the lungs is bad, is because water isn’t oxygen. But it’s not like the water itself is directly causing damage.
Your lungs, like every part of your body, already have lots of water. In fact the blood vessels in your lungs, which are there to absorb O2 and excrete CO2, work best when they are covered in a thin layer of water.
There is almost always water in the air you breathe. There is water in the air you breathe in and in the air you breathe out. Normally there is a bit more in the air your breathe out, meaning that most of the time breathing causes a slight net loss of water.
The situation you described, breathing while you’re in a warm wet shower, is one of the few situations in which you’re likely breathing in more water than you are breathing out. Still, each breath adds a small amount of water compared to what’s already there. Your lungs have been evolving to carefully manage their water content for literally hundreds of millions of years. They can handle a bit extra from the moist air of your shower quite easily.
I remember in “the perfect storm” commentary – one of the actors said he was told that during the storm there was enough water “mist” in the air that you could drown…
Breathing the very wet air.
This in physics often seem to be certain: water or air, or land
But often it turns out to be just useful constructs that we have to help us navigate.
For example:
Binocular vision is a joke (for example and breaks in many ways: blind spots in each eye, speculating reflections break all the time and your mind just ignores it…
Or objects being “solid” (there’s way more space in a substance than there is matter)
Etc
The wider question would be, how come you don’t drown in your own spit and mucus, or get your lungs stuffed full of dust.
And the answer is that the mucus membrane that covers the inside of your lungs is covered by cilia, microscopic tubular structures on surfaces of your cells that waft back and forth and continuously push mucus out of your lungs so you end up continuously swallowing it all. [https://en.wikipedia.org/wiki/Respiratory_epithelium#/media/File:Blausen_0766_RespiratoryEpithelium.png](https://en.wikipedia.org/wiki/Cilium#/media/File:Blausen_0766_RespiratoryEpithelium.png)
Steam is invisible and scaldingly hot, the cloudy stuff you can see coming off of boiling water is just the water vapor that has condensed in the cooler air.
Have you ever seen that photo of the people standing in that massive underground crystal mine?
Those Gypsum crystals are located 1,000 feet below the Sierra de Naica Mountain in Chihuahua, Mexico. The miners pumped out the cave that was filled with water to reveal the crystals.
The tempature inside that mine was 136 degrees Fahrenheit with a near 100% humidity. Water needed to be constantly pumped out due to the surrounding flood chambers.
Without a special cooling suit, you would die within 10 minutes of heat stroke. If you didn’t die of heatstroke, you would drown to death from the condensation. Miners could only enter with special suits for 20 – 30 minutes at a time.
The cave has since been sealed with water.
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