"I only had one bad sunburn there once." Dr. Aubriana McEvoy, a Mohs surgeon at Siteman Cancer Center and a dermatology professor at WashU Medicine, hears versions of that line all the time. "And that's exactly where we end up treating a skin cancer," she said.
When she examines those same patients, the rest of their skin tells a different story. "We commonly see more sun damage and skin cancers on the left hand and forearm from years of incidental exposure through the car window," McEvoy said. The sunburn the patient remembers is the one they blame. The years of "normal" exposure that actually built the skin cancer are the years no one thinks about.
That asymmetry, with the left side worse than the right, is one Dr. James Chao sees constantly. Chao is a board-certified facial plastic surgeon in San Diego, and one-sided damage from driving is common enough to have its own name.
"Unilateral dermatoheliosis is something we see as facial plastic surgeons," Chao said. Standard side car windows block only 55 to 75% of UVA rays. "Your left cheek, temple and ear can take in years of sun damage while driving to and from work every day. What happens down the road is patients come in with uneven sun damage or photoaging. The left side of the face may have more sun spots and nasolabial folds that are just deeper."
In Australia or the United Kingdom, it's the right side. The asymmetry is the giveaway.
Dr. Amy Bandy, a board-certified plastic and reconstructive surgeon, said the bigger misunderstanding is what counts as sun exposure in the first place.
"It's easy to be exposed to a peak window of ultraviolet radiation from 10 a.m. to 12 p.m. while watching your child play soccer on Saturday," Bandy said. "It doesn't matter how cool it may feel or what the wind speed is. You're still getting some of your highest levels of UV radiation. The same goes when you run errands between 11 a.m. and 2 p.m., walk your dog down the street every day or stand outside waiting for your kids to get off the bus without any protective covering from the sun."
She tells patients to do the math. Fifteen unprotected minutes a day adds up to roughly 90 hours a year. "Multiply that by 10 or 20 years, and you've accumulated thousands of hours of unprotected UV radiation exposure."
Cloudy days don't reset the count, either. "UVA light is prevalent year-round and penetrates through glass surfaces," said Dr. Rosanne Paul, an assistant professor of dermatology at Case Western Reserve University. "Even in the spring and summer when there is cloud cover, UV light still penetrates and you should still wear sunscreen."
Some of the most exposed skin is the skin nobody thinks to protect. The top of the head is one.
"Skin cancers are very common in the part lines of people," said Dr. Purvisha Patel, a board-certified dermatologist and Mohs surgeon in Memphis, Tennessee. Parting your hair in the same place year after year leaves the same strip of scalp exposed to cumulative damage most people never notice, she said. Patel tells patients to rotate the part and wear a hat outdoors. Creams can't get through hair, she said, making the scalp the one place where spray sunscreen earns its keep. The skin around the eyes is another blind spot, and the source of the damage is one almost no patient suspects.
"We spend a lot of time with our heads tilted downward so our phones sit just below our line of sight," said Dr. Gregg Feinerman, a board-certified ophthalmologist in Newport Beach, California. "This position perfectly angles our upper eyelids, eyebrows and temples directly at UV rays shining down from the sun. Most sunglasses don't cover this area, which means you could have two to three unprotected square inches of the most delicate skin on your entire body exposed to UV rays every time you're outside between 10 a.m. and 4 p.m."
Years later, Feinerman said, those patients arrive with thickened upper-eyelid skin and basal cell carcinomas in places they "can't quite remember getting."
Bandy can map the damage by decade. "After 10 years of exposure, I have begun to notice small amounts of uneven pigmentation starting to appear, along with freckles lasting longer, new sun spots forming, and my patients' overall skin color is slightly duller due to slower cell turnover," she said. By 20 years, Bandy said, established sun spots set in, along with permanent wrinkles that don't smooth out when the face relaxes. After 30 years, the changes are no longer cosmetic. Collagen and elastin break down, and precancerous lesions appear.
Much of that damage is preventable. The trouble is, many patients have been doing the prevention wrong.
Patel said the most common mistake is incorrect sunscreen application. "Sunscreen is meant to be applied on clean, dry skin to be effective," she said. "We cannot control for the efficacy and longevity of a product when it is put on top of or under makeup or moisturizers." Most adults under-apply, she added, recommending a nickel-sized amount for the face. Bandy adds that even correctly applied sunscreen needs reapplying after two hours outside.
For anyone weighing the cost of doing more, Chao has advice. Fixing a 1-centimeter defect on the nasal tip or eyelid can take up to three hours of surgery and leave permanent changes to the face. "We simply cannot recreate some of these structures," he said. Prevention, by his reckoning, runs around $30 a month in sunscreen, plus $5 to $20 per window for UV-blocking film. "It could prevent you from ever needing Mohs surgery."
McEvoy's advice is shorter than the list of exposures. "Make sun protection part of your routine, not something you only think about at the beach," she said. That means sunscreen on ordinary days, and covering the scalp part, ears, hands and eyelids. It also means knowing your own skin, because most skin cancers are first spotted by patients themselves. "Look for the ugly duckling, a spot that stands out, or anything that's changing, bleeding, or not healing," she said.
The line she repeats most often is the one she wishes patients heard first.
"There's no such thing as a healthy tan. A tan is a visible sign of DNA damage in the skin."
Dermatologists' Top Sunscreen Picks
Blue Lizard Sensitive Mineral Sunscreen SPF 50+
This reef-safe mineral sunscreen from Australia contains no active chemicals and is suitable for sensitive skin. It is sweat- and water-resistant for up to 80 minutes.
EltaMD UV Clear SPF 46
Formulated with hyaluronic acid and lactic acid, this mineral SPF is lightweight and comfortable under makeup, ideal for sensitive and acne-prone skin.
CeraVe AM Facial Moisturizing Lotion with SPF 30
An affordable option that provides sun protection while moisturizing, with ceramides, hyaluronic acid, and niacinamide. Non-comedogenic and fragrance-free.
Ultra Violette Future Screen SPF 50
This Australian brand's sunscreen is packed with mineral blockers and feels silky and lightweight.
La Roche-Posay Anthelios Clear Skin Sunscreen Dry Touch SPF 60
Oil-free and water-resistant, this sunscreen contains antioxidants and senna alata to combat oxidative stress. Suitable for sensitive skin.
Isdin Eryfotona Actinica SPF 50+
100% mineral-based with zinc oxide, DNA repair enzymes, and vitamin E. Lightweight and matte finish, good for sensitive skin and rosacea.
EltaMD UV AOX Mist SPF 40
Water-resistant mist that sprays on white and dries clear, with 360-degree sprayability for full body coverage.
Elemis Pro-Collagen SPF 50
Sheer, imperceptible fluid that dries down quickly with no white cast, leaving skin radiant and dewy.
La Roche-Posay Anthelios Tinted Light Fluid Sunscreen SPF 50
Mineral tinted fluid with universal tint, offering high UVA/UVB protection with 100% mineral filters. Ideal for sensitive skin.
Neutrogena Sheer Zinc Oxide Dry-Touch Mineral Sunscreen SPF 50
Water-resistant for 80 minutes, lightweight and non-greasy, with zinc oxide as the active ingredient.
EltaMD UV Restore SPF 40
Combines physical blockers with antioxidants like niacinamide, vitamin C, and DNA-repair enzymes to combat oxidative stress.
Merit The Uniform Tinted Mineral SPF 45
Lightweight and buildable with a sheer finish, available in 15 hues. Provides a natural glow and helps blur skin imperfections.
Lancer Mineral Sun Shield Universal Tint SPF 30
Lightweight tinted mineral SPF with antioxidants, iron oxides for blue light protection, and soothing ingredients that blend into all skin tones.
