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The Heat Is On: Physical Effects of Humidity

 Humidity causes all kinds of unwanted physical effects on the body. From frizzy hair to dilated blood vessels, it’s important to protect yourself when the weather gets warm and moisture levels rise.

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I haven’t felt like myself all day today, and I think the weather’s to blame. It’s uncharacteristically muggy outside, which somehow makes my brain as frazzled as my hair. What is it about humidity that pulls our bodies so forcefully out of whack? Heavy downpours and dry heat don’t seem to have the same startling effects. Sure, the former’s depressing and the latter’s tiring. But when excess moisture in the air combines with high temperatures, the results are far too overwhelming, at least for me. It makes me want to seek shelter indoors, and not just to hide my humidity-crazed hair from public view.

I assumed my lethargy and frizzy hair in humid conditions were due to general weather weakness (which is also why I hate any temperature below sixty degrees) and bad hair genes. But it turns out that a high level of water vapor in the air does have physical effects on the body. And for some people with preexisting health conditions, it might actually be dangerous.

The Effect on Hairstyles
I can’t quite blame humidity for making my hair extra frizzy, because it’s only exaggerating my hair’s natural curliness. If my hair were straight as an arrow, humidity would make it go limp instead. This is because of humidity’s effect on hair’s temporary hydrogen bonds, which give hair a certain amount of flexibility when it comes to style (i.e., making straight hair curly, or vice versa). When there’s too much water in the air, it breaks down hydrogen bonds and allows permanent sulfur bonds—which dictate each hair strand’s predisposed shape—to shine through even more. That’s why naturally wavy or curly hair turns downright frizzy, and straight hair turns droopy and lackluster.

The Effect on Energy Levels
When the air’s more moisture-rich than usual, it feels even hotter than it really is, making us that much more tired. High temperatures outside get our bodies working overtime to maintain a stable, comfortable temperature on the inside. That’s why we release sweat in the first place: to remove excess heat internally and cool off as the sweat evaporates from our skin. But in humid situations, the air’s so waterlogged that it can’t absorb moisture as quickly, if at all, depending on humidity levels. The sweat has nowhere to go, so it overheats the body even more in the process. Blood vessels dilate to release heat, sending more blood to the skin surface and less to our brain and internal organs. All of this is why we feel so weak and out of it during humid times.

Two separate studies have shown that humidity can have an adverse effect on mental and physical capacities. The first one, published in a 1976 edition of the Journal of Applied Psychology, found that hot, humid conditions at sea level were just as physically debilitating as hypoxia (a lack of oxygen) at high altitude. A more recent study conducted in 2008 and published in the Indian Journal of Occupational and Environmental Medicine found that working in an abnormally humid factory caused workers severe mental stress, in contrast with the moderate stress levels of workers in a factory of average humidity.

The Effect on Physical Health

Most people experience stubborn hair and sluggishness when the weather turns humid, but those are minor annoyances compared with the effects it can have on some people. Past research has linked high levels of water vapor in the air with increased symptom flare-ups in arthritis and rheumatoid arthritis sufferers, though the reason behind the supposed link is unknown.

A few studies have shown a correlation between humidity and asthma attacks as well. One in particular, performed at the University of Michigan and published in a 2009 issue of Annals of Allergy, Asthma, & Immunology, had particularly compelling results. Researchers reviewed two years’ worth of emergency room admissions at a Detroit children’s hospital. They found that when humidity went up at least 10 percent, there was a rise in asthma attacks. A few theories attempt to explain why this connection might exist—excess moisture makes the air heavier to breathe, for example—but more research is needed to come to a definitive conclusion.

Illness due to heat is a potentially life-threatening effect of high-humidity situations that can strike just about anyone. Because the body can’t release heat as efficiently, overheating—otherwise known as hyperthermia—becomes more likely. That can lead to heatstroke, characterized by vomiting, dizziness, headaches, muscle cramps, a rapid drop in blood pressure (which takes much-needed blood away from the brain), and a quickened pulse. It can lead to internal-organ damage if not treated right away. People with cardiovascular problems are at an increased risk for hyperthermia, as are the elderly and very young, people with weakened immune systems, and the overweight.

How to Protect Ourselves
Evidently, the wear and tear humidity triggers isn’t all in our heads—it’s in our bodies, too. Clearly, if we’re not careful when it’s humid out, something worse than a bad hair day could occur. Consider this a helpful reminder to take it easy when moisture levels in the air are noticeably high. (As if any of us needed an excuse to do that.) Don’t exercise too much, and be mindful of water consumption, since dehydration is a frequent cause of heatstroke on hot, humid days. If possible, seek shelter in an air-conditioned room; the Centers for Disease Control and Prevention say it’s the best way to protect ourselves from overheating and heat-related illnesses.

As for humidity’s aesthetic effects, there’s not much we can do about them. At least we can take comfort knowing that all the people around us are probably too busy worrying about their own hair situations to notice our own. Just throw on a hat, gulp down some water, relax in a cool area, and hope for the best.

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