However, the additional security is little. SPF 50 sunscreen blocks 98 percent of UVB radiation, whereas SPF 100 sunscreen blocks 99 percent. When applied appropriately, sunscreen with SPF values ranging from 30 to 50 provides effective sunburn protection, even for the most sun-sensitive individuals. Higher SPFs are not necessarily better; they just provide more protection. Individuals who have a history of skin cancer or other severe reactions to sunlight should always use a sunscreen with a high SPF.
When you set your SPF level higher than 50, you reduce your chances of developing skin cancers and aging wrinkles due to exposure to the sun's harmful rays. However, this extra safety margin means that you may need to apply your sunscreen more frequently. Use a good quality sunscreen with an SPF of at least 30 before you go into the sun. If you suffer from asthma, allergies, or heart disease, you may want to choose a lower SPF value.
Even if you rarely go in the sun, it is important to protect yourself from overexposure because ultraviolet light can travel deep into outer space where it causes nuclear radiation damage to satellites and other material on board spacecraft. This damage could lead to catastrophic results for astronauts aboard these vehicles.
The key word here is "often" because there are some studies that say you shouldn't use SPFs more than 50.
The SPF rating compares the time it would take to sunburn if you were not using sunscreen to the time it would take if you were wearing sunscreen. Spencer claims that an SPF 15 product protects around 94 percent of UVB rays, an SPF 30 product blocks approximately 97 percent of UVB rays, and an SPF 45 product blocks approximately 98 percent of rays. However, this number is only useful for comparing products with similar levels of protection.
Products with higher SPFs usually provide better coverage and last longer before needing to be reapplied. Some people may also prefer products with higher SPFs because they feel like they give more protection than recommended doses of less-effective products. Products with SPFs of 50 or more are common but there are also many cosmetic products on the market with SPFs of 10 or less.
The SPF number appears on labels in two forms: as a single digit number followed by a percentage sign (e.g., 15%) or as a word ("broadband"). There are three types of sunscreen filters: chemical, physical, and biological. Chemical filters include ingredients such as benzophenones, salicylates, and oxybenzins. These act by absorbing specific wavelengths of light. Physical filters include micronized minerals such as titanium dioxide or zinc oxide. They work by reflecting back any harmful rays that make it through the skin's surface. Biological filters include extracts from plants such as soybean or wheat seed coats.
SPF 30 is the most often used rating for the majority of people and skin types. There is no sunscreen that can completely block all UV rays, but we do know that SPF 15 blocks 93 percent of UVB rays, SPF 30 blocks 97 percent of UVB rays, and SPF 50 blocks 98 percent of UVB rays. So the difference between 30 and 50 is around 1%. While SPF 100 blocks all UV radiation, this level of protection is recommended only for those who have never had a sunburn before (and even then only in rare cases).
The higher the number, the longer your sunscreen will last on your skin. Because UVA rays are invisible to the human eye, you need to protect against them with a product labeled as "UVA protective." Such products are usually marked with the term "broad-spectrum" along with the number of minutes needed to provide full protection. For example, Neutrogena's UVA Broad-Spectrum Sunblock Spray provides protection for up to 40 minutes.
It is important to apply a new coat of sunscreen every day because the more exposure your skin gets to sunlight the more damage it will suffer over time. And just like any other part of your body, the skin needs food, water, and rest to be healthy and happy. If you wear sunscreen but still go outside without covering up or sitting in the sun for long periods of time, you're putting yourself at risk for developing skin cancer.
Sunscreen should not be used as a replacement for proper sun protection techniques.
Sunscreen with an SPF of at least 30 is recommended by experts. Sunscreens with SPFs higher than 50 offer just a marginal boost in UV protection. SPFs with a high number last the same length of time as SPFs with a low number. However, ones with an SPF of 70 or more may provide greater protection from skin cancer.
The higher the SPF, the longer it will take before you have to re-apply your sunscreen. Sunscreen should be applied every day, even when it's cloudy out or not exposed to the sun for very long periods of time (like during winter).
Just like any other product that contacts your skin, sunscreen can cause problems if you have certain allergies. If you know you are allergic to pollen, dust, soy, antibiotics, or latex; you should avoid sunscreen products containing these ingredients. Some people may also have adverse reactions to zinc oxide or titanium dioxide, which are both included in sunscreen products. If you experience any rash, hives, difficulty breathing, or swelling around your eyes you should seek medical attention immediately.