During the warmer weather and longer days of summer, you may be spending more time catching some rays. But it's important to practice sun safety to protect yourself from skin cancer. Applying sunscreen helps reduce the risk of skin cancer, but not all SPF levels are created equal. Here's what you need to know in order to get the best protection possible.
How does sunscreen reduce skin cancer risk?
The skin is the body's largest organ and has several layers. The two main layers are called the epidermis (outer layer) and the dermis (inner layer). Skin cancer begins in the epidermis, which is made of three kinds of cells: basal, squamous and melanocytes. The three major types of skin cancer — basal, squamous and melanoma — begin in each of these cells respectively.
Basal and squamous cell carcinomas are the two most common types of skin cancer. They can usually be cured if they're detected and treated early. Melanoma can also be cured if it's treated early — but it's the most dangerous skin cancer because it can spread to other parts of the body.
Skin cancer can be caused by overexposure to ultraviolet (UV) rays from the sun, sunlamps or tanning beds. There are three types of UV radiation:
- UVA rays have the least energy, but they can cause skin cells to age or cause indirect damage to skin cell DNA. They can play a role in some skin cancers.
- UVB rays have more energy than UVA rays and can cause direct damage to the DNA in skin cells. They're thought to cause most skin cancers.
- UVC rays have the most energy, but they react with ozone high in the atmosphere and don't reach the ground. However, they can be found in man-made products such as UV sanitizing bulbs. UVC rays aren't usually a risk factor for skin cancer.
Sunscreen helps protect against harmful UV rays. Chemical sunscreens absorb the sun's rays, while physical sunscreens sit on the skin's surface and deflect rays. Sunscreen is available as a lotion, cream, gel, spray, wax stick or ointment.
What do SPF levels mean?
You're likely familiar with the term "SPF" — or sun protection factor — that appears on sunscreen labels. The number that accompanies it is a measurement of how well it protects the skin against sunburn. The American Academy of Dermatology (AAD) recommends an SPF of 30 or higher when going outdoors, even if it's cloudy outside. About 80% of the sun's rays can penetrate clouds.
A higher SPF number is better to a certain extent, but no sunscreen can block 100% of the sun's rays. Here's how the numbers break down:
- SPF 15 blocks 93% of UVB rays
- SPF 30 blocks 97% of UVB rays
- SPF 50 blocks 98% of UVB rays
- SPF 100 blocks 99% of UVB rays
No matter which SPF you choose, you need to use the proper amount to cover your body. The AAD recommends using 1 ounce to cover all exposed skin. That includes your feet, hands, neck, top of your head and ears. Apply sunscreen 15 minutes before going outside and reapply it every two hours. You'll also need to reapply sunscreen after swimming or sweating. Remember that water-resistant doesn't mean waterproof. If a sunscreen label says it's water-resistant, it should also say how long it lasts while swimming or sweating; often, it’s either 40 or 80 minutes.
You'll also want to take the time of day into consideration when choosing a sunscreen. UV rays are strongest between 10 a.m. and 2 p.m. If you can't stay indoors during those hours, choose a higher SPF sunscreen.
Do different skin types and skin tones need different sunscreens?
Contrary to popular belief, people with darker skin tones also need to wear sunscreen to protect against skin cancer. While melanin — the pigment that gives skin its color — helps block some of the sun's rays, it doesn't offer complete protection. SPF 30 is the minimum recommendation for all skin tones.
You should also take your skin type into consideration when choosing a sunscreen. If you have dry skin, look for a sunscreen with hyaluronic acid and a moisturizing agent. Choose an oil-free sunscreen if you have oily or acne-prone skin.
Do you need sunscreen indoors?
It might seem counterintuitive since staying in is one way to protect yourself from sunburn, but you should also wear sunscreen inside. The sun's rays can go through windows and make contact with your skin, so staying indoors doesn't offer total protection unless you're in a room with no windows or drawn curtains.
How do you check for skin cancer?
Although sunscreen can reduce the risk of skin cancer, it doesn't prevent it completely. Starting at age 20, you should perform full body self-exams and discuss whether regular skin exams from a doctor may be appropriate based on your risk level. Getting to know your skin by performing a self-exam each month can help you identify any changes that might indicate cancer. Look for anything unusual such as moles or spots that are growing or bleeding. The AAD suggests looking for the ABCDEs of melanoma:
- Asymmetry: Half of the spot is unlike the other.
- Border: The spot's border is irregular or poorly defined.
- Color: The spot has varying colors.
- Diameter: The spot has a diameter the size of a pencil eraser (6 millimeters), although some can be smaller.
- Evolving: The spot looks different from others or is changing size, shape or color.
Common signs of skin cancer can also include smooth, waxy bumps or firm, red lumps. If you notice any of these signs, you should contact your primary care doctor or dermatologist.
Talk to your doctor if you have any concerns about your risk for skin cancer. Remember to practice sun safety this summer and throughout the year!