Step 1: Look for the 3 essentials To protect your skin from the sun's harmful rays, you want to use a sunscreen that offers all of the following: SPF 30 (or higher) Broad-spectrum protection (UVA/UVB) Water resistance.
To know if sunscreen is effective, look for the SPF number on the bottle. SPF stands for sun protection factor. The higher the SPF number, the more protection the sunscreen provides.
SPF tests are done by putting 2 milligrams per square centimetre of sunscreen on the backs of human volunteers. A special UV lamp is shone onto the backs, and how much UV the skin can take with and without the sunscreen is compared.
In addition to SPF, we need to make sure our sunscreen follows a few simple criteria to be truly effective. The first is to find sunscreens that are listed as “broad-spectrum.” This term means that the sunscreen protects users against not only UVB radiation—which is responsible for causing sunburns—but UVA as well.
It has been found that in average conditions, a sunscreen with SPF 50 will last for approximately 3 to 4 hours [9]. If you're on the move, sweating, or in a place with a particularly strong UV index, it is recommended to apply SPF 50 sunscreen every 2 to 3 hours.
Poor Packaging Quality: Spelling errors, blurry logos, or mismatched fonts are signs of counterfeits. Unfamiliar Sellers: Purchase from trusted retailers or the brand's official website. Lack of Seals: Authentic sunscreens usually have safety seals or tamper-proof packaging.
Due to the health concerns associated with oxybenzone, EWG recommends consumers avoid sunscreens with oxybenzone. Octinoxate is a non-mineral UV filter.
Verify the product.
The FDA regulates sunscreen products, it is highly advised to purchase only products that have been notified with the FDA. To check if a product is notified with the FDA, use the FDA Verification Portal feature accessible at https://verification.fda.gov.ph.
If you are concerned about health effects, the safest choice is a so-called “mineral” or “physical” sunscreen with zinc oxide or titanium dioxide, dermatologists say. Those are the only sunscreen ingredients that the FDA says are “generally recognized as safe and effective.”
Best Overall: EltaMD UV Clear Face Sunscreen SPF 46
Despite the high 46 SPF, the lightweight formula is powered by a combination of transparent zinc oxide and octinoxate that won't leave a white cast, even on darker skin tones.
OR, you can obtain some black construction paper and smear some samples of sunscreen on the paper. Use about the same amount you would use on your face/body. Multiple stripes/trials = good. Then set the paper out in the direct sun and check every hour or so and record your observations.
If there is no expiration date on the bottle, you should opt for a new sunscreen product with a valid expiration date. An expired sunscreen can become liquidy or grainy in texture, have an usual smell, or turn yellow in color.
SPF TESTING. SPF test measures the level of protection provided by a sunscreen. To perform this test, the study records how long it takes for a participant to sunburn without wearing sunscreen.
The test area is air dried prior to exposure from the solar simulator using 25% increments. The exact series of exposures given is determined by the control MED and the expected SPF of the product. One test site area of 40 sq.cm serves to determine each subject's Minimal Erythema Dose (MEDu).
During SPF email authentication, a receiving mail server performs an SPF check to verify that the domain in the "envelope from" address in the email header matches a valid IP address in the SPF record. If the addresses don't match, the email fails the SPF test and the email can be rejected by the email receiver.
But the extra protection is negligible. Properly applied SPF 50 sunscreen blocks 98 percent of UVB rays; SPF 100 blocks 99 percent. When used correctly, sunscreen with SPF values between 30 and 50 offers adequate sunburn protection, even for people most sensitive to sunburn.
Wearing SPF is just one part of a wrinkle-prevention plan but it's certainly something you should do every day if you want to prevent those signs of aging (and other effects of UV radiation). You don't necessarily need to wear SPF 50 to do this — as long as you're wearing the standard recommendation you should be fine.
Some sunscreens include an expiration date — a date indicating when they're no longer effective. Discard sunscreen that is past its expiration date. If you buy sunscreen that doesn't have an expiration date, write the date of purchase on the bottle.