Like wearing a seatbelt in the car, applying sunscreen in the sun is just one of those things you know you’re supposed to do. Despite our best efforts to practice sun safety, though, according to the CDC, the rates of skin cancer are on the rise (even though incidences of other cancers are declining). Those rates are projected to reverse and start to go down by 2030, though, thanks to increased awareness around proper prevention methods, like applying SPF. Sunscreen and SPF may seem straightforward enough, but it’s not always as easy to understand what all those numbers on your sunscreen mean. So, we talked to dermatologist Dr. Tess Mauricio, CEO of MBeauty Clinic, about the SPF basics and what everyone should know before stepping into the sun.
What is SPF?
SPF, or sun protection factor, blocks harmful ultraviolet rays from hurting our skin. That said, SPF is only a measure of how well your sunscreen can protect you from UVB rays, the rays that affect the epidermis, or outer layer, of the skin. The sun actually emits three types of rays: UVA, UVB, and UVC rays. UVC rays typically don’t pass through the ozone layer. Let’s break down UVA and UVB a bit more.
These are the most common rays and make up about 95 percent of the ultraviolet radiation that reaches earth. UVA rays cause both skin aging and skin cancer. They are also present all year so you need protection from these rays no matter the season or even time of day. They aren’t, however, primarily responsible for sunburns as they don’t stop at the epidermis of the skin. UVA rays penetrate into the dermis layer and, therefore, are more responsible for skin cancers like melanoma.
These rays cause sunburn, skin cancer, and contribute to premature aging. UVB rays are more prevalent from the spring to fall and in the late morning to late afternoon. And again, SPF protects against UVB rays.
Differences in Sunscreens
There are many different types of sunscreens (lotions, mists, sticks, etc.) and they don’t all contain the same amount of SPF, so it’s important to stay diligent about what’s best for your skin individual skin type.
Dr. Mauricio also adds that there are different forms of sun protection. “There are two categories of sunscreen: physical blockers and chemical blockers,” she says. Physical sunscreens are made up of active mineral ingredients. They work by deflecting UV rays to anywhere other than the skin. Physical blockers also tend to block both UVA and UVB rays. But they tend to come off easily with things like sweat or water so regular reapplication is necessary.
Chemical blockers contain organic material, like carbon, and work by absorbing the rays from the sun and chemically converting them to heat which releases from the skin. These sunscreens are usually thinner and easier to apply, making them ideal for daily use. In addition, because of how chemical formulas work, users typically don’t need to worry about blotches or missed areas. However, chemical blockers involve increasing the skin’s temperature so there is a risk of coloring and the formation of brown spots. So, you may see freckles coming through or moles start to appear over time. Additionally, chemical sunscreens with an SPF over 50 and those with combined UVA and UVB protection may be more likely to cause skin irritation for those with sensitive skin because of the additional ingredients in the formula.
What about broad-spectrum sunscreen?
Ideally, you should purchase a sunscreen that protects against both types of UV rays. Enter: broad-spectrum. Sunscreens are tested against the broad-spectrum test that measures a product’s UVA protection relative to its UVB protection. If a sunscreen is labeled broad-spectrum, that means it protects against both types of rays. In these cases, SPF values measure the overall magnitude of protection. Only broad-spectrum sunscreens with an SPF valued 15 or higher can claim to reduce the risk of skin cancer and early skin aging. Sunscreens that aren’t broad spectrum and have an SPF value between two and 14 can only prevent against sunburn.
Breaking Down SPF Numbers
According to Dr. Mauricio, SPF numbers indicate the inverse fraction of the number of UV rays that can penetrate the skin. “For example with SPF 15, 1/15 of the rays that can penetrate the skin. So the higher the number, the better,” she says. Once the number passes SPF 50, protection rates increase more slowly.
Still confused about what sunscreen to grab? Look for a broad spectrum, water-resistant sunscreen with SPF 30. And then apply it liberally and continue to reapply throughout the day. A higher SPF doesn’t necessarily mean you’re protected for a longer period of time. Factors like time, sweat, and water exposure all contribute to lowering a sunscreen’s power over time.
In addition to wearing SPF and sunscreen, pay close attention to your skin. Being the largest organ in the human body, it’s your responsibility to keep it healthy. Check yourself regularly for any changes in skin coloration, texture, or any new moles or growths. Make sure you visit your dermatologist at least once a year for a full body skin check and analysis. It could mean the difference between life and death by skin cancer.
SPF and Aging
According to Dr. Mauricio, SPF is also responsible for keeping your skin hydrated, preventing sunburn, reducing your risk of skin cancer, and even reducing the signs of aging. “With regular sunscreen use, one can slow down unnecessary skin aging caused by the sun,” she says. “The signs include discoloration, wrinkles, and sagging.”
The exposure to UV rays on our bodies places stress and exposure on our epidermis (the outer layer of the skin) which forces us into premature aging. So while many spend hundreds of dollars on beauty serums and creams, or even thousands on anti-aging procedures, the most beneficial and cost-effective solution is simply using SPF on our skin every day. Because of this, Dr. Mauricio stresses the importance of applying sunscreen to the face every day. Women can purchase makeup or moisturizer that includes SPF and men can usually find aftershaves or daily moisturizers that also include it.