Can Acid Rain Really Cause Hair Loss? [Kim Jin-oh's Hair Loss Escape]

[Financial News]  It has long been said that getting caught in acid rain makes your hair fall out. However, there is no clinical evidence that getting rained on in everyday life causes hair loss. There is no need to worry that briefly getting caught in the rain without an umbrella will damage your hair roots or worsen hair loss.

If your hair is already thinning, even minor things can be a source of worry. Even if you notice strands falling out while washing your hair after getting caught in the rain, it is difficult to say that they fell out because of that day's rainwater.
First, there is no need to regard the word “acid” as something especially dangerous. The surface of human skin is naturally slightly acidic, too. Neutral water has a pH of 7, while healthy skin generally has a surface pH of around 5. A slightly acidic environment helps maintain the skin barrier and a normal microbial environment. In other words, acidity itself is not harmful to the skin.
Of course, the fact that acid rain has an acidity similar to that of skin does not mean it is safe. Its composition and concentration, as well as how long it stays on the scalp, also matter. People are not forests or lakes fully exposed to falling rain. They are only caught in it “briefly.” So there is no reason to think of brief exposure to acid rain as being like exposure to a strong acid chemical. The U.S. Environmental Protection Agency also explains that getting caught in acid rain is no more dangerous to human health than getting caught in ordinary rain.

The skin barrier is also much stronger than we might think. In the outermost layer of skin, the stratum corneum, multiple layers of corneocytes are stacked together, with lipids densely filling the spaces between them. As a result, many external substances cannot easily penetrate the skin. Even when developing topical medicines, how much of an active ingredient can pass through the skin is important enough to be a major research question. The extent of penetration varies according to the ingredient's size and properties, so simply applying something to the skin does not mean it will reach as far inside as desired. It also depends on whether the skin barrier is intact.
Experiments in which human hair follicles and follicular cells were directly exposed to fine particulate matter did show inflammatory responses and cell damage. But direct contact between pollutants and cells isolated from the skin is different from rainwater reaching a scalp with an intact skin barrier. We cannot assume that the same amount of pollutants on the scalp is delivered straight to follicular cells.
In particular, a study using human skin tissue repeatedly removed the stratum corneum with tape. The researchers found that the more of this layer they removed, the more deeply and extensively fine particulate matter penetrated. This shows that the skin barrier normally provides substantial protection. It does not block every pollutant completely, but a healthy scalp should not be thought of as equivalent to cultured cells directly exposed to pollutants.

Rainwater can contain dust or air pollutants, and a wet scalp environment can increase the likelihood of fungal growth. When possible, use an umbrella, and, depending on the situation, it is a good idea to cover your head with a hat that can keep the rain off.
If you have already been caught in the rain, simply care for your hair as usual. If it is very wet or feels unpleasant because of dust and sweat, wash it with your usual shampoo after you get home and dry it gently. Lightly pat away the moisture with a towel, and avoid directing hot air from a hair dryer at one spot for too long. There is no need to rush off to wash your hair just because you got a little rain on it, or to scrub your scalp hard several times to get rid of the rainwater.
You do not need to spend your time worrying about everything that touches your scalp just because you are managing hair loss. Simply bringing an umbrella or hat when you can avoid the rain is a perfectly good precaution.

/Kim Jin-oh, Director of New Hair Plastic Surgery Clinic 
[email protected] Kim Hyeon-seon Reporter