Why You Need It? How it Works for You?
Sun Protection Factor (cream with SPF)
SPF is a measure of how much solar energy (UV radiation) is required to produce sunburn on protected skin (i.e., in the presence of sunscreen) relative to the amount of solar energy required to produce sunburn on unprotected skin. As the SPF value increases, sunburn protection increases. There is a popular misconception that SPF relates to time of solar exposure. For example, many consumers believe that, if they normally get sunburn in one hour, then an SPF 15 sunscreen allows them to stay in the sun 15 hours (i.e., 15 times longer) without getting sunburn. This is not true because cream with SPF is not directly related to time of solar exposure but to amount of solar exposure. Although solar energy amount is related to solar exposure time, there are other factors that impact the amount of solar energy. For example, the intensity of the solar energy impacts the amount. The following exposures may result in the same amount of solar energy:
- one hour at 9:00 a.m.
- 15 minutes at 1:00 p.m.
Generally, it takes less time to be exposed to the same amount of solar energy at midday compared to early morning or late evening because the sun is more intense at midday relative to the other times. Solar intensity is also related to geographic location, with greater solar intensity occurring at lower latitudes. Because clouds absorb solar energy, solar intensity is generally greater on clear days than cloudy days.
In addition to solar intensity, there are a number of other factor that influence the amount of solar energy that a consumer is exposed to:
- skin type
- amount of sunscreen applied
- reapplication frequency
Fair-skinned consumers are likely to absorb more solar energy than dark-skinned consumers under the same conditions. The amount of sunscreen applied also impacts the amount of solar radiation absorbed, because more sunscreen results in less solar energy absorption. Because sunscreens wear off and become less effective with time, the frequency with which they are reapplied is critical to limiting absorption of solar radiation. The reapplication frequency is also impacted by the activities that consumers are involved in. For example, consumers who swim while wearing sunscreen need to reapply the sunscreen more frequently because water may wash the sunscreen from the body. In addition, high levels of physical activity require more frequent reapplication because the activity may physically rub off the sunscreen and heavy sweating may wash off the sunscreen. In general, more frequent reapplication is associated with decreased absorption of solar radiation.
Because of the various factors that impact the amount of solar radiation, SPF does not reflect time in the sun. In other words, cream SPF does not inform consumers about the time that can be spent in the sun without getting sunburn. Rather, cream with spf is a relative measure of the amount of sunburn protection provided by sunscreens. It allows consumers to compare the level of sunburn protection provided by different sunscreens. For example, consumers know that cream with SPF 30 sunscreens provide more sunburn protection than cream with SPF 8 sunscreens.
How SPF Is Determined
The SPF number is determined through indoor experiments that expose human subjects to a light spectrum meant to mimic the noontime sun (when the sun's rays are at their most intense). Some subjects wear sunscreen and others do not. The amount of light that induces redness in sunscreen-protected skin, divided by the amount of light that induces redness in unprotected skin is the SPF
What the CREAM WITH SPF Number Means
A higher SPF doesn't indicate superior sun protection—it indicates that you will remain protected in the sun for a longer amount of time.
For example, an SPF 2 product protects your skin just as effectively as one with an SPF of 30. However, cream with spf 2 sunscreen will need to be applied more frequently.
To be safe, no matter what SPF you choose, it's best to reapply sunscreen at least every two hours, as well as after swimming or sweating. In fact, the American Academy of Dermatology recommends daily application of cream with spf 30 to all exposed skin.
UVA vs. UVB Rays
The SPF only indicates the level of protection against the sun's ultraviolet B rays, which are called UVBs for short. Initially, UVB rays were thought to be the only UV rays to worry about, since they are shorter in length and cause sunburn. However, ultraviolet A (UVA) rays also pose risks. They age the skin and contribute to skin cancer. SPF alone does not protect against UVA rays.
In order to get the best sun protection possible, look for a sunscreen that provides both UVA and UVB protection.
REQUENTLY ASKED QUESTIONS
What is the UV index?
The UVI (ultraviolet index) is a data table that measures the risk of sun exposure when it emits varying levels of UV radiation. Depending on time of day and location, the sun produces different amounts of UV radiation so these numbers will vary. The index is organized from low to high numbers, starting with zero (most safe) to 11 or greater (extremely dangerous).
Does higher SPF matter?
Yes, higher SPF does matter, but the effects of sunscreen greater than SPF 30 may not be meaningful enough to justify its use. Sunscreens with a higher SPF count only block a slightly higher amount of UVB rays. Most people will see meaningful sun protection with SPF 30 products as long as the sunscreen is applied every two hours and after swimming.
What CREAM WITH SPF sunscreen should I use for my face?
You should use a sunscreen that is SPF 30 or higher for your face. It can be the same sunscreen used for your body and should cover every area of exposed skin. Ideally, the sunscreen should offer both UVA and UVB protection, which is often marked as "broad spectrum" or "full spectrum." It's possible for skin cancer to affect your lips, so it may also be helpful to use a lip balm that offers sun protection of SPF 30 or higher.
Decrease your risk of skin cancers and skin precancers. Regular daily use of cream with spf15 sunscreen can reduce your risk of developing squamous cell carcinoma (SCC) by about 40 percent, and lower your melanoma risk by 50 percent
Help prevent premature skin aging caused by the sun, including wrinkles, sagging and age spots.
Who should use sunscreen?
The short answer is everyone! Men, women and children over 6 months of age should use sunscreen every day. This includes people who tan easily and those who don’t — remember, your skin is damaged by sun exposure over your lifetime, whether or not you burn.
Babies under the age of 6 months are the only exceptions; their skin is highly sensitive. Stay out of the sun; shade structures and sun-protective clothing are the best ways to safeguard infants.
What type of sunscreen should you use?
With so many choices, how do you pick a sunscreen that’s right for you? The Skin Cancer Foundation believes that the best sunscreen is the one you are most likely to use, so long as it provides safe and effective protection, and is broad spectrum with an SPF 15 or higher. Learn about your options to make an informed choice that best suits your needs. The happier you are with your sunscreen, the more consistently you’ll use it.
Sunscreen ingredients
Sunscreen includes active ingredients that help prevent the sun’s UV radiation from reaching your skin. Here’s how the two types of sunscreen work for you:
- Physical (mineral) sunscreen ingredients (including the minerals titanium dioxide and zinc oxide) block and scatter the rays before they penetrate your skin.
- Chemical sunscreen ingredients (like avobenzone and octisalate) absorb UV rays before they can damage your skin.
What level of CREAM WITH SPF do I need?
If you’re inside most of the day with just short intervals in the sun, you can use a sunscreen or cosmetic product with an SPF of 15 or higher. If you spend a lot of time outdoors, especially when and where the sun is strongest, you need an SPF 30 or higher, water-resistant sunscreen. More about SPF.
No matter the SPF, reapplication every two hours is key. Sunscreen must also be reapplied immediately after swimming or sweating.
Broad-spectrum protection
In the past, most sunscreens only included information on product labels about protection against UVB — the rays that cause sunburn, and not UVA — the rays that cause tanning and premature aging. Now that UVA dangers are well known, broad-spectrum sunscreen provides clear information on product labels about protection against both UVB and UVA.
Choosing a sunscreen: What to look for?
- Broad spectrum: Protects your skin from both UVA and UVB rays.
- CREAM WITH SPF 15: Ideal for every day, occasional exposure, like walking your dog, or driving to work.
- CREAM WITH SPF 30 or higher: Necessary for extended outdoor activities, including distance running, hiking, swimming and outdoor sports. SPF 30 is a must if you work outdoors.
- Water resistant and very water resistant: For swimming or intense exercise. No sunscreen is waterproof; they all eventually wash off. Sunscreens labeled water resistant are tested to be effective for up to 40 minutes of swimming, while very water resistant sunscreens stay effective for up to 80 minutes in the water.
When should I apply sunscreen?
Every day! The best practice is to apply 30 minutes before venturing outside to allow the sunscreen to bind to your skin. Reapply every two hours of exposure and immediately after swimming or excessive sweating.
Even when it’s cloudy, up to 80 percent of the sun’s UV radiation reaches the earth. Going unprotected on an overcast day can lead to skin damage.
Where should I apply sunscreen?
Experts recommend applying sunscreen to your entire body before you dress for the day. That way your skin will be protected if your clothing shifts or you remove layers. At the very least, you should use sunscreen on every part of your body that is exposed to the sun, including those easy-to-miss spots: the tops of your ears, back of your neck, your scalp (on the part line), tops of your feet and behind your knees.
Why should I use sunscreen?
Sunscreen reduces your overall UV exposure and lowers your risk of skin cancer and sun damage.
Other things to consider
- Your skin cancer risk factors: Your skin type and family history will determine the level of protection needed for you.
- Photosensitivity: No matter your skin type, certain medications and disorders make your skin highly sensitive to the sun, raising your protection requirements.
- Skin conditions: You can choose from sunscreens for dry skin, oily skin, acne-prone skin and sensitive skin.
Live a sun-safe life
Keep in mind that while crucial, sunscreen alone is not enough. Seek the shade whenever possible, wear sun-safe clothing, a wide-brimmed hat and UV-blocking sunglasses, for a complete sun protection strategy.
Sources:
https://www.fda.gov/about-fda/center-drug-evaluation-and-research-cder/sun-protection-factor-spf
https://www.verywellhealth.com/what-is-spf-1068889
https://www.skincancer.org/skin-cancer-prevention/sun-protection/sunscreen/
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Prepared by Viktorija Stučytė based on online sources
