You must apply sunscreen liberally on all parts of your body that are exposed. A recent dermatological study published said, “Sunscreen users are only applying 50 percent of the recommended amount, so they are only receiving 50 percent of the SPF protection.” Because of the need for liberal application, expensive sunscreens can be dangerous to your skin’s health. After all, how likely are you to liberally apply a really expensive sunscreen!
According to the US cosmetics cop and much respected beauty writer Paula Begoun “there are brilliantly formulated sunscreens in all price ranges, expensive definitely does not mean better when choosing sun protection creams”
Although some believe that sunblock and sunscreen are both the same, they are not. Although they have similar properties and are both important in caring of the skin, sunblock is opaque and is stronger than sunscreen since it’s able to block a majority of the UVA/UVB rays and radiation from the sun, thus not having to be reapplied several times a day. Titanium Dioxide and Zinc Oxide are two of the important ingredients in sunblock.
Sunscreen is more transparent once applied to the skin and also has the ability to protect against UVA/UVB rays as well. Although the sunscreen’s ingredients have the ability to break down at a faster rate once exposed to sunlight, and some of the radiation is able to penetrate to the skin. In order for sunscreen to be more effective you’ll have to consistently reapply and use a higher SPF
Sunscreens labeled as “waterproof” are not really waterproof (which is why the FDA is urging manufacturers to stop using this term). No sunscreen is “waterproof.” You need to reapply sunscreen after swimming, towelling yourself off or when perspiring a lot.
UVA vs. UVB
UVB radiation is the sun’s burning ray and has an immediate, harmful impact on skin.
UVA rays are the sun’s silent killers. You don’t feel them but they are the primary cause of skin cancer, wrinkles, and a weakened immune system.
Even on a cloudy or hazy day, the sun’s rays are present and impacting on the skin.
It is dangerous for your skin not to have UVA protection and many sunscreens do not have ingredients that can provide true full-spectrum (both UVA and UVB) coverage. In most countries, including the U.S. and Canada, there are no numbers to tell you about protection from UVA radiation. For that protection you have to check the active ingredient list to see if either zinc oxide, titanium dioxide, avobenzone (which may also be listed as Parsol 1789 or butyl methoxydibenzoylmethane), Mexoryl SX, or Tinosorb (Tinosorb is only available in products sold outside the U.S.) If one of those isn’t part of the active ingredient list (it doesn’t count if it is just part of the regular or “other” ingredients) you are not applying adequate UVA protection and that is dangerous for your skin.
The SPF number does not tell you anything about a product’s quality. The SPF number is just a time limit number. A sunscreen rated SPF 2 blocks about 50% of UVB rays; an SPF 10 filters out about 85% of UVB rays; an SPF 15 stops about 95%; and an SPF 30 stops about 97%. An SPF that’s higher than 30 does not provide any more UV protection, it just offers more time that you can stay in the sun without burning.