A women hiker in a pink top and green backpack applies sunscreen to her face.

Practice sun safety this summer

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It is finally summertime in the PNW! And while it can be tempting to bask in our too-fleeting season of sun… it’s also important to protect your skin from the harmful radiation emitted by our brilliant local star.

Too much exposure to the sun can cause skin cancer, which is the most common form of cancer in the United States. The American Academy of Dermatology estimates that one in five Americans will develop skin cancer in their lifetime. Rates of its deadliest form, melanoma, have risen steadily over the past three decades; an estimated 200,000 new cases are diagnosed each year in the U.S.

A few years ago, one of those cases was Dr. Lindsay Gunnell, chief resident in the UW Department of Dermatology and Fred Hutchinson Cancer Center. After being diagnosed with melanoma while practicing family medicine at Swedish Health Services, she was inspired to begin researching skin oncology. This led to her current residency with UW Medicine.

We asked Dr. Gunnell to share her expertise on practicing sun safety to prevent skin problems down the road.

Lindsay Gunnell, MD

TWU: Why and how does sunlight damage our skin?

Lindsay Gunnell: Ultraviolet (UV) light penetrates below the surface layer of our skin and injures skin by directly damaging DNA. This triggers stem cells to divide and attempt to repair the damage, but that is an imperfect process. This damage accumulates over time leading to skin cancer and aging.

How much exposure leads to skin cancers?

Both intermittent burning — blistering sunburns are highest risk — and low levels of long-term exposure to UV light cause DNA damage. Tanning is a damage response and is not protective. Since it is impossible to predict how much UV damage will create any given skin cancer in a person, it is important to always use sun protection.

What is your advice for effective sun protection?

Sun protection should be a combination of seeking shade, wearing a hat, sunglasses and clothing, and applying sunscreen. Since every strategy has its own drawbacks, it’s best to layer them whenever possible. You should avoid being out in full sun during peak hours (10 a.m. to 4 p.m.). And check the UV Index on your phone’s weather app. Sun exposure is best avoided when the UV Index is higher than 6, indicating a high risk of harm from unprotected sun exposure.

When sun avoidance is impossible, quality clothing is the next best sun protection. This includes wearing a wide-brimmed hat, UV-blocking sunglasses and protective clothing. Darker colors and tighter weaves offer better protection. For example, a white cotton T-shirt has a UPF (like SPF but for clothing) rating of 9 while a gray cotton T-shirt has a UPF of 98! Wearing UPF-rated clothing gives the best security.

Beyond clothing, hat and sunglasses, you should apply sunscreen every day on all exposed surfaces of skin. There are many types of sunscreen, but the best sunscreen is one that you will actually wear!

What’s the proper way to apply sunscreen?

Ideally, sunscreen should be applied 20 minutes prior to sun exposure for both chemical and mineral formulations. This is because it takes a few minutes for sunscreen to settle into an even layer over the skin after application. A “shot glass” worth of sunscreen is needed to protect your entire body. More practically, one teaspoon of sunscreen will cover your face, ears, neck and the backs of your hands, the parts of our bodies most often exposed. Sunscreens spread best when warmed in the hands prior to application.

You do need to reapply sunscreen every two hours at a minimum — or every hour if you are swimming or sweating heavily. For chemical formulations, this is in part because many UV filters degrade over time in UV light. Mineral formulations tend to rub off inadvertently as you move, touch your face, etc.

Is any sunscreen really “waterproof?”

No. All sunscreen will wear off over time and with exposure to water and sweat. The American Academy of Dermatology recommends choosing water-resistant formulas, however, which are formulated to help sweat and water bead and run off, maintaining protection for short periods of time. When swimming or exercising, it’s best to go with sunscreen rated “water resistant 80 minutes).

Are spray sunscreens as effective as creams? 

Spray sunscreens are less effective than creams because people tend to get poor coverage overall when using a spray. In addition, inhaling mineral sunscreens (zinc oxide/titanium dioxide) may pose a risk to the lungs so these sunscreens should not be used in spray formulation.

A mother applies sunscreen lotion to a young girl's face at the beach

Is sunscreen harmful?

There is a myth going around social media platforms such as TikTok that wearing sunscreen is more harmful to our health than sun exposure is. This is simply not true. We have many decades of data on sunscreen safety in humans that have proven there is no harm from regular sunscreen use. Not protecting your skin, however, has been widely proven to cause skin cancer.

If you prefer to avoid chemical sunscreens, you can choose mineral formulations (such as zinc oxide/titanium dioxide) which do not get absorbed and carry the seal of approval from the FDA as GRASE (generally recognized as safe and effective).

Isn’t the sun a valuable source of vitamin D? What are safer ways of getting it? 

UVB leads to Vitamin D synthesis, but there is not a safe level exposure from the sun or indoor tanning devices that allows for maximum vitamin D synthesis without increasing skin cancer risk. Due to this, it is recommended that people get Vitamin D from the diet. If this is not possible, supplements may be needed.

Does taking vitamin A or other supplements protect the skin from sun damage? 

Vitamin A plays no role in protecting from sun damage although topical vitamin A (retinoids) and oral Vitamin A (isotretinoin, aka Accutane) can increase sun sensitivity. A diet high in fruits and vegetables contains a Vitamin A precursor — beta carotene — which acts as an antioxidant in the body but does not play a role in sun protection.

Studies show that one oral supplement, Polypodium leucotomos (Commercial name: Fernblock®) may provide some photoprotection, but it is not clear how much. That said, the safety data is encouraging, so certain patients may benefit from taking this.

Do only people with light-colored skin need to take precautions, or do darker complexions need protection, too?

Everyone needs sun protection — regardless of skin tone! UV damage occurs in all skin tones and can lead to cancer and aging. People with more pigment in their skin do have lower rates of skin cancer in general but higher relative rates of melanoma in unusual sites such as under the nails or in the eye. People with darker skin tones also have higher rates of irregular brown pigmentation caused by UV damage such as melasma. Sun protection can play a big role in treating and preventing this.

Does getting a “base tan” provide protection?

A tan is not a good form of sun protection, it is a sign of skin damage. A tan is the body’s feeble attempt to churn out pigment after damage has been done, but it is equivalent to about an SPF of 2, far below what is needed to actually protect our DNA from damage.

Do freckles provide protection?

Freckles are a genetic response to sun damage, typically in very light skin tones. Similar to a tan, they are not protective and are actually a sign that the skin has already had UV damage. Freckles are small, flat brown spots that only develop in sun-exposed areas, which is different from moles, which are not related to sun-exposure.

Are tanning beds safer than natural sunlight?

No. Tanning beds use the same harmful UV light that comes from the sun. Indoor tanning can increase the risk of developing the two most common types of skin cancer: squamous cell carcinoma by 58% and basal cell carcinoma by 24%. Using tanning beds before age 20 can increase your chances of developing melanoma by 47%, and the risk increases with each use.

Aren’t we somewhat protected in the PNW by our northern latitude and cloud cover?

This is false! Washington’s rate of skin cancer has increased over the past decade, with new melanoma cases here far outpacing the national average. Our cool and cloudy climate should not lead to a false sense of security. While clouds do block some UV light, they are far better at blocking visible light. Roughly 80% of UV rays penetrate cloud cover. You can definitely get sunburned on a cloudy day. So, it’s a good idea to check the UV index before going out. If the UV index is greater than 2, you should practice sun protection.

What is the biggest myth you encounter about sun care? 

The biggest myth I see is that people do not think they need to wear sunscreen every day. However, studies looking at groups of people who used sunscreen at their discretion only when they felt they needed it and compared to groups required to wear sunscreen daily showed that those who wore it only when they thought they needed it had twice the rate of melanoma! We are poor judges of when sun protection is needed. It is best to use sun protection every day, even if you think you might not be exposed.

How to recognize skin cancers

According to Dr. Gunnell, melanoma, the most dangerous form of skin cancer, can arise in any area of skin, nail or “wet skin” (such as the mouth, vagina or anus). It typically presents as a brown or black area that is changing. Dermatologists use the ABCDEs to teach what to look for:

  • Asymmetry – a non-uniform shape.
  • Borders – appear irregular or scalloped.
  • Colors – two or more shades or colors.
  • Diameter – greater than 0.6 cm (about the size of a pencil eraser).
  • Evolution – size, shape and appearance that changes over time.

Non-melanoma skin cancers (such as basal cell or squamous cell) typically present as pink bumps that are painful and bleed or get crusty.

The bottom line: anything on your skin that is growing, painful or bleeding should be checked out by a board-certified dermatologist.