Uh, Is Air-Drying Your Hair More Damaging Than Heat? We Got The Scoop

Heat harms your hair—we'll assume you're well aware of this hard truth. While you can take proactive measures to prevent breakage (i.e., a thermal protectant and low-heat setting), taking a hot tool to the strands ultimately restructures your hair pattern to get the results you want, which does a number on those bonds over time. Now, we're not going to shame anyone for occasionally plugging in the blow dryer, but we often say an air-dry is the best dry, if you can swing it. 

If all this science jargon leaves you scratching your head, here's a little hair anatomy for your day: Each strand is made up of three layers—the inner fiber called the medulla, the middle layer called the cortex, and an outer layer called the cuticle. Right on the outside of that middle cortex layer, you have the CMC. "The cell membrane complex is the material that glues hair cells together and is where hair hydration 'lives,'" explains hairstylist Miko Branch, co-founder of natural hair care brand Miss Jessie's. "When the CMC layer is exposed, you lose essential hydration, which can cause damage to the hair shaft." 

Your hair is also structurally at its weakest when it's wet, as the strands swell up with water—so if your hair stays wet for a long period of time, the CMC "glue" holding the hair cells together can start to expand, and that's when you can run into a concern called hygral fatigue2 (or damage from excessive moisture). From there, you might experience brittle strands, tangling, frizz, breakage, and low elasticity, says Branch. 

However! That's all assuming your hair stays wet and fragile for a long, long time. "I don't think 'air-drying' is the problem. I think air-drying for an extended period of time is problematic," says celebrity curl expert Nai'vasha, founder of Curl Queen. "The weight of wet strands for an excessive time plus the hygral fatigue is where the breakage starts, in my opinion, versus air-drying in its entirety." So let's all take a breath and let go of the notion that air-drying itself is more damaging than heat. Wet strands are extremely vulnerable, yes, but if your hair naturally dries rather quickly, you should have little to worry about. 

In fact, that brings me to an important point: It looks like this study didn't take participants' hair texture and porosity into account, which totally could have influenced the results. For instance, low porosity hair takes longer to dry after getting wet, as the denser cuticles are holding all that water in. So someone with low porosity hair might have experienced more structural damage from the air-dry, as the CMC tends to swell up for longer.