That's a question I've gone back and forth on my whole life. I remember being told in school that hair is not really alive, it's dead cells making it's way out of the follicle. Which goes along with the theory that police, examiners, etc will use a few strands of freshly pulled hair to run tests to see if there had been drug use in the last 6 months (something they can't get from blood alone).
But if you ready beauty magazines, where they tell you tons of ideas to make your hair beautiful, you tend to believe that maybe the hair is really alive.
Dr, Zoe D. Draelos, MD, FAAD, consulting professor at Duke University School of Medicine, Durham, N.C. spoke at last year's 69th Annual Meeting of the American Academy of Dermatology (Academy).
In that speech, he stated that hair is not living, and despite what beauty product makers would like you to believe, it can not heal itself once it is damaged. Dr. Draelos explained that "For this reason, once the hair is damaged it cannot heal itself except through new hair growth at the scalp. Women need to understand that the very things that they do to hair to make it appear beautiful, such as using hair dyes, perms and products that straighten the hair, will eventually end up damaging the hair’s structure and ultimately affect its appearance.”
Hair, while dead, has a layer of fat on the outside of the cuticle, making the hair shiny and pretty. Chemical treatments, such as perms, colors, and yes Chlorine can strip that cuticle of the lipids, and cause dried-out, frizzy hair.
The biggest thing to combat damaged hair, as I mentioned the other day, is MOISTURIZE! You need to use shampoo that will add as much moisture to the hair as possible to minimize the damage and stop creating even more damage to your hair.
Dr. Draelos suggests looking for products containing dimethicone. Dimethicone been shown to decrease static electricity, increase shine and improve manageability. It may not magically fix it, but if you're looking at a few different products and one lists Dimethicone, why not try that one to see if there's a difference to your hair.
Another cause of damaged hair is one I'm personally guilty of, heat damage. I must admit when the Remington Wet to Straight came out, I was the first on the bandwagon. It was great. It's a flat-iron, but as you run it through your hair, it actually dries and straightens at the same time. Most flat-irons flatten, but you're left with scalding hot wet hair at the end.
Dr. Draelos suggests that damage "occurs when the water in the hair, which makes the hair flexible, gets heated and turns into steam. Hair bubbles then occur on the hair shaft, creating a loss of cuticle." He also warns that "Hair damaged by heat cannot be repaired, as the affected hair will need to be cut off and allowed to regrow as healthy hair."
So, for once and for all, hair is already dead, BUT you can damage it further and cause hair loss if you don't protect it.