Decoding Sunscreen: Understanding SPF
Sunscreen is a vital component of skincare, especially during sunny summer months when UV radiation is at its highest. However, sunscreen labels can often be confusing and intimidating, leaving users unsure about the meaning of SPF numbers, broad-spectrum protection, and water resistance. This lack of understanding can lead to misuse or even avoidance of sunscreen, putting people at risk for skin damage and disease. To combat this, the following article aims to demystify these terms, debunk common sunscreen myths, and provide reliable, evidence-based advice on how to choose and correctly use sunscreen. Through this, we hope to empower readers to make informed decisions about their sun protection.
What is Sunscreen?
Sunscreen is a skincare product that, when applied to the skin, helps protect it from the harmful ultraviolet (UV) rays emitted by the sun. These UV rays are a leading cause of sunburn, premature skin aging, and skin cancer. Sunscreens achieve this protection by employing various active ingredients that either absorb the UV rays, thus preventing them from penetrating the skin, or reflect the rays away from the skin.
The Importance of Sunscreen
The importance of sunscreen cannot be overstated. It acts as a first line of defense against the sun's harmful rays, preventing them from causing cellular damage to your skin. Regular use of sunscreen can save your skin from the harmful effects of UV radiation, including sunburn, premature aging, and even skin cancer, making it a critical part of any comprehensive skin care routine.
Types of Sunscreens
There are two main types of sunscreens: physical (or mineral) sunscreens and chemical sunscreens. Physical sunscreens create a physical barrier that reflects or scatters UV light. The active ingredients in these sunscreens are usually zinc oxide or titanium dioxide. Chemical sunscreens, on the other hand, absorb UV light and convert it into heat that is then released from the skin. Some common active ingredients in chemical sunscreens include avobenzone, oxybenzone, octinoxate, and homosalate. Sunscreens may also be differentiated by their SPF rating or its broad-spectrum protection. There are also various forms of sunscreen such as lotions, sprays, sticks, and gels. Lotions are the most common and are suitable for most situations and skin types. Sprays can be convenient but may not provide as even or reliable coverage as lotions. Sticks are useful for areas around the eyes or for spot application, and gels are often preferred for hairy areas like the scalp or male chest.
Decoding the SPF Number
What Does SPF Mean?
SPF stands for Sun Protection Factor. It's a rating system that measures a sunscreen's ability to protect your skin from UVB rays, which are a type of UV radiation that causes sunburn and contributes significantly to skin cancer. This rating is a crucial factor in choosing a sunscreen that fits your needs and lifestyle. SPF does not measure protection from UVA rays.
How SPF Works
Contrary to common belief, SPF is not a measure of time, but rather a measure of the amount of UV radiation it takes to cause sunburn on skin protected with sunscreen versus unprotected skin. For instance, if you typically burn after 10 minutes in the sun, an SPF 30 sunscreen would theoretically protect you for 30 times longer, amounting to 300 minutes (about 5 hours). However, this calculation assumes perfect application and does not account for factors such as sweat, water, or the varying intensity of sunlight throughout the day.
The Concept of Broad-Spectrum Protection Broad-spectrum protection is a term that refers to a sunscreen's ability to protect your skin from both types of harmful UV rays: UVA and UVB. UVB rays are primarily responsible for sunburn, while UVA rays penetrate deeper into the skin, leading to premature aging, such as wrinkles and age spots. Broad-spectrum sunscreens are designed to shield your skin from both of these harmful rays, providing comprehensive sun protection.
Quantity: When applying sunscreen, many people don't use enough. The recommended amount is about an ounce (30 ml), roughly equivalent to a shot glass full, for the entire body for each application. This might seem like a lot, but it's the amount used in testing when SPF is determined. Using less than this amount will provide less than the listed SPF.
Coverage: It's important to apply sunscreen evenly and cover all exposed skin. People often forget about certain spots like the ears, the back of the neck, the tops of the feet, and even the scalp if your hair is thinning or you have bald patches. Lips can also get sunburned, so a lip balm with SPF should be used.
Timing: Sunscreen should be applied about 30 minutes before going outside. This allows the ingredients to fully bind to the skin, providing the best protection.
Reapplication: Sunscreen isn't a one-and-done application for the day; it needs to be reapplied at least every two hours. It should also be reapplied immediately after sweating heavily or swimming, even if the sunscreen is labeled as water-resistant. Water-resistant sunscreens are tested to be effective for 40 minutes or 80 minutes when swimming or sweating, but it's a good idea to reapply when you're drying off just to be sure.
SPF Makeup: If you're relying on makeup with SPF for your facial sun protection, keep in mind that you likely need to apply more than you think to get the full listed SPF, and it should still be reapplied every two hours.
Cloudy Days and Shade: Even on cloudy days or when in the shade, up to 80% of the sun's harmful UV rays can still reach your skin. Applying sunscreen should be a daily routine, not just for sunny days or beach outings.
Expired Sunscreen: Check your sunscreen's expiration date. Expired sunscreen may not provide the level of protection stated on the bottle. If your sunscreen doesn't have an expiration date, a general rule of thumb is that sunscreens are designed to last for three years, but this can be shorter if it has been stored in high temperatures.
Understanding Water Resistance in Sunscreens
When a sunscreen is labeled as water-resistant, it means that it retains its sun protection properties while you are in the water or sweating. However, it's crucial to understand that no sunscreen is entirely waterproof or sweatproof. This means you should reapply it at least every 2 hours and immediately after swimming or excessive sweating.
Everyone Needs Sunscreen
Regardless of skin type or color, everyone can get skin cancer, so everyone should wear sunscreen. Even if you tan easily or have a darker skin tone, you're not protected against skin damage from the sun's harmful rays.
Skin Cancer: Skin cancer doesn't discriminate by skin type or color. While it's true that individuals with lighter skin, who burn more easily, are at a higher risk, that doesn't mean those with darker skin are immune. Skin cancer can affect anyone, regardless of skin color. This is because the sun's UV rays can lead to DNA damage in the skin cells, a major factor in the development of skin cancer.
Melanin is Not Sufficient Protection: Melanin is the pigment that gives skin, hair, and eyes their color, and darker-skinned individuals have more melanin than those with light skin. While melanin does provide some protection against the sun's UV rays (equivalent to about SPF 13.4 for black skin and 3.4 for white skin), it's not enough to prevent skin damage entirely. Furthermore, melanin is less effective at diffusing UVA radiation, which can lead to premature aging and the potential for skin cancer.
Tanning: Some people may think that if they tan and don't burn, they don't need sunscreen. But a tan is actually a sign of skin damage, as it's the skin's response to harmful UV radiation. Over time, this damage can lead to accelerated skin aging and increased risk of skin cancer.
Risk for Severe Outcomes: When skin cancer does occur in individuals with darker skin, it is often detected at a later stage, when it's more difficult to treat. Additionally, certain types of skin cancer, like acral lentiginous melanoma (ALM), are more common in people of color and can be more deadly.
Prevention is Key: Regular daily use of SPF 15 or higher sunscreen reduces the risk of developing squamous cell carcinoma by about 40% and the risk of developing melanoma by 50%. Therefore, regardless of your skin type or color, it's vital to make sunscreen a part of your daily routine and to take other protective measures, like wearing sun-protective clothing and seeking shade during peak sun hours. Remember, while sunscreen can protect you from harmful UV rays, it's not a license to spend unlimited time in the sun. Other protective measures, like seeking shade, wearing protective clothing, and avoiding peak sun hours, should be part of your sun protection routine.
Here are the common myths about sunscreen: 1. Sunscreen is not always necessary: Many people believe that sunscreen is only necessary when their entire body is exposed to sunlight, such as when at the pool or swimming in the ocean. However, ultraviolet light is still harmful to exposed skin, no matter how much of it is exposed. It is best to cover the exposed skin with sunscreen and consider other protective methods, such as wearing a hat.
2. Sunscreen will prevent the body from absorbing vitamin D: While sunscreen does block UV rays, which the body uses to create vitamin D, sunlight can penetrate clothing, sunscreens lose their effectiveness over time, and people often forget to put sunscreen on every time they see the sun. Just 5 to 30 minutes of sun exposure per day can create the proper amount of vitamin D in the body.
3. Sunscreen causes health problems: This myth comes from an older study done on oxybenzone, one of the active ingredients in many sunscreens. The levels of exposure this study reached to produce health problems in rats were extremely high and unattainable in humans, even those who use sunscreen regularly and liberally.
4. People with dark skin do not need sunscreen: While people with darker skin are more protected from the sun, they should still use a full spectrum sunscreen. UVA damage is not blocked by melanin in the same way and can lead to premature skin aging and wrinkles. Melanin will also not protect the skin from extreme sun exposure, such as spending long hours in the sun unprotected. People with darker skin are also not protected against skin cancer.
5. Tanning beds provide a protective base tan: Tanning beds use high concentrations of UVA light to darken the skin quickly, whereas the sun includes both UVA and UVB light. A temporary tan from a tanning bed will do very little to protect the skin from sun exposure and sunburns caused by UVB light.
6. Makeup is enough to protect the face: While it is true that makeup may provide a little protection from the sun, it is not much and is not a replacement for a good sunscreen. Makeup should be seen as an additional layer of protection, not the only layer of protection.
7. Sunscreen works better than covering up: Covering up the skin is much better protection than sunscreen. A long-brimmed hat and clothing will protect the skin better than any sunscreen.
8. You cannot tan while wearing sunscreen: Sunscreen helps protect against UVA and UVB rays, but it may not protect the body completely. It is still possible to get a tan while using sunscreen.
9. Waterproof sunscreen is completely water-resistant: No sunscreen is completely waterproof or sweatproof. A sunscreen can only be water-resistant for a specific amount of time.
10. Higher SPF equals much longer protection: SPF rating is not a perfect measure of duration of protection. Sunscreens should be reapplied approximately every two hours, regardless of SPF rating.
11. All sunscreens protect against both UVA and UVB rays: Not all sunscreens are "broad spectrum," meaning that they protect against both UVA and UVB rays. It's important to choose a broad-spectrum sunscreen to protect against skin aging, sunburn, and skin cancer.
12. The FDA thoroughly tests all sunscreens: The FDA does regulate sunscreens, but not all sunscreens are created equal. It's important to choose a sunscreen from a reputable brand and to follow the application instructions to ensure you're effectively protected against the sun.