Summer Hair Care Tips: What Sun, Chlorine, Salt and Sweat Do to Your Hair

Chlorine gets the blame when blond hair turns green at the pool, but chlorine alone doesn't do it. The color comes from copper, which often goes into pool water on purpose, to kill algae.

Summer hair advice tends to roll the pool, the beach, the gym and the sun into one vague threat called damage. They do different things to your hair, and each has its own fix, most of them free or close to it.

Does the sun damage your hair?

Yes: strong sunlight breaks down some of the protein in hair and shifts its color. In a 2004 lab study of black, brown, blond and red hair, lamps and real sunlight both increased protein loss in every type, with UVB doing about two to five times the damage of UVA and visible light combined. Color changed in every type too, most visibly in light hair, and UVA was mainly behind that. The researchers found no significant change in the hair's mechanical properties, so there's no need to panic over one beach week.

The fix is to cover it. The American Academy of Dermatology (AAD) suggests a wide-brimmed hat or a leave-in conditioner with zinc oxide. A baseball cap covers the crown and the part, but your ears, neck and ponytail stay in the sun. UV runs highest from late morning through mid-afternoon. In the desert Southwest, with month after month of clear skies, a hat is daily advice. Elsewhere it's for the long days: a ball game, a Saturday in the yard.

Your scalp needs its own protection. Hair blocks some UV, but the Skin Cancer Foundation says your part, the hairline and any thinning spots need more: a hat, ideally labeled UPF 50+, or sunscreen put on while your hair is dry.

What does chlorine do to your hair?

Pool chemicals can roughen hair and change its color, and heavy swimmers show it clearly. A study of Japan's national swimming team found discolored hair in 61 percent of the swimmers and in none of the 54 people they were compared with. Under an electron microscope, the golden hairs sampled from eight swimmers had lost their cuticle, the outer layer of the strand. The authors blamed friction with the water for that, and chlorine compounds for reaching the pigment inside. Elite athletes log far more pool hours than anyone on a family vacation, so treat this as the far end of the scale.

A short routine covers most of it:

1. Before you get in: wet your hair. A Cleveland Clinic dermatologist advises it so that hair takes up less chlorine. The CDC already asks for a one-minute shower before swimming, to keep dirt and sweat from using up the pool's disinfectant, so you can do both at once.
2. In the water: wear a swim cap, especially if you swim laps or your hair is light or bleached.
3. Right after: rinse your hair before it dries.
4. At home: use a swimmers' shampoo, then a deep conditioner, which is the AAD's routine for swimmers.

If the green has already arrived, look for a swimmers' or "chlorine removal" shampoo containing EDTA, which binds metals and lifts copper out of hair, according to a chemistry lecturer writing in The Conversation. She knows of no scientific evidence for ketchup, which will disappoint several generations of camp counselors. Damaged hair picks up the most copper, and light hair shows it most. If it's your own pool, have the copper level tested.

Is salt water bad for your hair?

Salt water can leave hair rough and hard to comb, but we found much less evidence of lasting harm than for sun or chlorine. Most of the research is lab work with artificial seawater, and it points to duller hair that takes more force to comb. A long day at the beach also means hours of sun, so the hat may do more for you than anything you do about the salt.

Rinse with fresh water before you leave if there's a beach shower, then work conditioner through at home and detangle with a wide-tooth comb. If an evening swim means going to bed damp, sleeping with wet hair has its own answer.

Is sweat bad for your hair?

We couldn't find good evidence that sweat itself harms healthy hair, and most of what you'll read on the subject comes from companies selling hair care. The trouble is what comes with it. A sweaty ponytail is damp hair under tension, and the AAD says hair is delicate when wet and warns against styles pulled tight. After a long run on a humid morning, loosen it. Hair accessories that damage hair covers which ties cause the most trouble.

Wash when your scalp asks. The AAD ties shampooing to how oily you get: straight hair with an oily scalp may want it every day, while dry, curly or textured hair can go up to two or three weeks. If you washed yesterday and sweated hard today, a plain water rinse and some conditioner can get you through. A scalp that keeps itching or flaking is one for a dermatologist.

Why does humidity make your hair frizz?

Hair takes up water from humid air, and that water changes temporary bonds inside each strand, so it swells and loses its set. On a July afternoon in New Orleans, nothing you did at home will stop that entirely, though conditioner and a styling product can slow it. Under dry desert heat you may get the opposite complaint: flyaways and brittle-feeling ends. Why does my hair frizz explains the causes, and how to reduce frizz lays out a routine for both climates.

Can silk help your hair in summer?

A little, and mostly at night. Silk won't block the pool, the salt or the humidity. Its smooth surface makes for less friction than cotton, and many people find that means fewer tangles and less frizz by morning. By day, a long silk scarf tied over your hair looks good on a boat, but without a UPF rating you can't know how much UV gets through, so don't rely on it for your scalp.

Any hat does the sun part. If you want a smooth surface against your hair as well, the silk-lined LS Silk baseball cap has a cotton shell, a 100% mulberry silk lining and an adjustable back.

See the silk-lined baseball cap →

By Labor Day most of this has washed or grown out. The green goes with the right shampoo, and the copper goes back to fighting algae, which is all it came for.

Frequently asked questions

Does chlorine turn hair green?

Not by itself. The green comes from copper, which gets into pools from algae treatments and corroding pipes and then binds to hair. Chlorine makes it worse by damaging hair so copper attaches more easily, and light hair shows it most.

How do you get green out of hair from the pool?

Use a swimmers' or chlorine-removal shampoo containing EDTA, an ingredient that binds metals such as copper, and follow with a deep conditioner. If your hair is bleached or the tint won't shift, ask your stylist before trying anything stronger.

Should you wet your hair before swimming?

Yes. A Cleveland Clinic dermatologist advises it so hair takes up less chlorine, and the CDC asks swimmers to shower for a minute before getting in anyway. Add a swim cap if you swim laps or your hair is light or bleached.

Should you wash your hair every day in summer?

Only if your scalp needs it. The American Academy of Dermatology ties shampooing to how oily you get, so straight hair with an oily scalp may want it daily while dry, curly or textured hair can go much longer. After a sweaty workout, a water rinse and conditioner is another option.

Do you need sunscreen on your scalp?

If your part, hairline or any thinning spots are exposed, cover them. The Skin Cancer Foundation calls a hat, ideally labeled UPF 50+, probably the best protection for your scalp. If you go without one, apply sunscreen while your hair is dry.

How do you protect your hair at the beach?

Wear a hat for the sun, rinse with fresh water before you leave if you can, and work conditioner through once you're home. Detangle with a wide-tooth comb, starting after straight hair has dried a little and while tight curls are still damp.

Related reading: How to Protect Your Hair While You Sleep · Winter Hair Care Routine · Is a Silk Bonnet Too Hot for Summer?