Huh? Air Drying is Bad for Hair?

Don't panic, air-drying is not going on your list of things you need to feel guilty about. Won't you join me in getting all "critical thinking-y" about this subject?

This post is in response to a blog reader's question about a recent study which reported that air-dried hair acquires some internal damage during drying whereas blow-dried hair accumulates more external damage. The study was published in the Annals of Dermatology, November, 2011: Hair Shaft Damage from Heat and Drying Time of Hair Dryer, Lee et. al. 

If you thought air-drying was best for hair - this catches you off guard, to be sure. But while I did a double-take when I saw that eye-grabbing factoid in what I think of as "hair social media" - after reading the article I think this information was taken out of proper context. In other words, it makes a great headline, but there is not enough information provided to support the idea that air drying is bad. Please, read on.

Some things to consider before digging in:
A) I don't think the authors made a solid case against air-drying, nor did they set out to do that. They are simply reporting an unexpected result, not condemning air-drying of hair. Human hair is made to air-dry. 

B) Blow-drying does a fair amount of surface damage; cracking the cuticles of the hair thanks to the rapid change in temperature and moisture. Cracked cuticles are rough and stick up. When cuticles stick up, they break off easily. The result of too much blow drying is dull, dry, rough, porous hair. 

C) Air-drying causes a lot less surface damage so your hair is not so rough or dull. That's why it is better for hair's feel and appearance, long-term.

D) The internal damage recorded in this study of the air-dried hair is of unknown consequence. Human hair has been air-dried for generations upon generations. Are we going to condemn it based on one study that found an interesting result but drew no conclusions based on that result? 

E) Researchers were not able to control how the hair was dried before it was used as a sample. This is an uncontrolled variable. We don't how the history of this hair sample/these hair samples may have influenced the outcome. Picky, picky! 

F) What is unclear to me is - did they use just one hair sample? How many heads of hair were represented here? The same hair sample for all 5 treatments? It looks like each treatment was a 2 gram sample of hair. This is not enough information for me. I would call a test based on one sample a "case study," not an experimental result.

The actual test was to repeat these treatments once per day, 30 times total in hair which is probably straight or wavy hair (from De Meo Brothers, Inc.). The hair was washed in a shampoo containing 10% sodium lauryl sulfate (the absolute concentration of detergent as a raw ingredient is not stated, but this is actually on the low side for a shampoo), then excess water was "shaken" off and the hair was dried using the following treatments: 

1) Hair with no treatment - no washing or drying (control)
2) Air-dry hair at room temperature of 20°C (68°F)
3) Hair dryer, "low" temperature for 60 seconds, 47°C (116° F) at 15 cm (6 inches) away from hair
4) Hair dryer "medium-high" temperature for 30 seconds, 61°C  (142°F) at 10 cm (4 inches) away from hair
5) Hair dryer "high" temperature for 15 seconds, 90°C (203°F) at 5 cm (2 inches) away from hair.

Note: No conditioner, no oils, no heat protectant, no styling products. This is only meant to test the "naked" hairs.

So what did they find?

-With increasing heat, there is more surface/cuticle damage, despite shorter exposure to heat as they turned the heat up.

-With air drying (which took 2 hours) there was bulging in the portion of the hair beneath the cuticles as a result of the time the hair spent wet. This is the piece of information that has been popularized in magazines and social media. I remind you - this may have occurred in a single hair sample. This does not necessarily mean everybody's hair acts like this. We simply do not know. The authors did not or could not provide that information about their hair samples.

Why did they get this result in air-dried hair?

When normal porosity and porous hair is wetted, it absorbs water. As it absorbs water, it swells - but it is the inner portion which includes the cell membrane complex which does the swelling. Shampoos increase swelling unless they contain very mild detergents or very dilute detergents. The cuticle layer cannot swell or increase in girth. So we have a problem - a swelling interior and a non-swelling exterior!  That's stress - kind of like frozen water inside a pipe. More about that in this blog post. 

Is this a problem for hair? We don't know for certain. Too much swelling in hair probably makes hair a little weaker in structure. If you spend a day in the rain with your hair wet, it becomes more troublesome - tangly, behaving differently. If you spend a lot of time swimming - even in fresh water - your hair will weaken. That swelling of hair pushes cuticles up so they are easily broken off and water has access to the cuticle layer and beneath and can leach away anything water-soluble and probably even some oils. These actions increase porosity.

What would be a convincing result? I think a similar test would need to be done on hair from multiple donors, including a variety of hair widths (fine/medium, coarse, very coarse), including curly and kinking and coily (type 4) hair. A more convincing sample size (to me) would be about 3-5 of each of these. A result you can replicate is a result you can trust better. If most hairs showed the same effect from air drying but not from blow-drying, then we can make some real conclusions. But we still wouldn't know the actual implications of the so-called damage. Maybe that's not structural damage at all. Maybe it's normal. It's not as though hair is meant to last forever.

What's good about air drying?

Air drying causes less cuticle damage (porosity) and cosmetic damage than heat-drying. It makes some people's hair frizz less. You can do lots of activities while your hair air-dries - you're not tied to a hair dryer. 

How to Air Dry Without feeling Like We're Slowly Destroying Our Hair? (I enjoy a little hyperbole). One of these may fit your lifestyle and hair styling requirements.

1) Use hair-penetrating oil treatments for 6-12 hours, especially on the length of your hair. Use coconut oil or sunflower oil, or olive or castor oil. These will help normal porosity and porous hair behave as though it is less-porous. It will swell less in water and you can avoid this problem. This really works. You don't have to soak your hair with oil either. See this post for details. You may even find you have a faster drying time with these treatments over time. 

2) Squeeze water out of your hair (styled or not) before air-drying. It will dry more quickly. Use a microfiber towel, an old t-shirt, a pillowcase or a cotton dish towel (tea towel/flour sack towel) to avoid creating frizz.

3) Limit your time under the water.  The less time your hair spends under water, the less saturated it will be. Yes, sometimes we need to get our hair all wet and juicy to be hydrated. But too wet for too long = waterlogged.

4) Wash or wet your hair less often. Works for some hair and lifestyles, not others.

5) Go as light on the styling products as possible. Lots of leave-in conditioner and hair gel causes longer drying times.

6) If your haircut is all-one-length, thick hair that takes forever to dry, getting some well-placed layers will shorten your drying time.

How long is too long to spend with wet hair? Nobody knows for sure. If your hair dries in 1 to 3 hours, you're probably okay. If your hair takes all day to dry, it may be getting stressed from all that time spent in a wet state. 

Bottom line: Air drying is better for the surface of your hair  than heat-drying with a blow dryer. There isn't any clear evidence that air drying is bad for your hair at all. But spending too long with your hair in a wet state is stressful, including very long dry-times.