SPF 15 product blocks about 94% of UVB rays; an SPF 30 product blocks 97% of UVB rays; and an SPF 45 product blocks about 98% of rays.
Mineral sunscreens typically include ingredients like zinc oxide or titanium dioxide, which create a physical barrier to protect the skin from the sun.
Chemical sunscreens use one or more chemicals including oxybenzone, avobenzone, octisalate, octocrylene, homosalate and octinoxate.
The SPF refers to the ability of a sunscreen to block UVB rays that can cause sunburns, as well as UVA rays, that can cause deeper skin damage.
Sunscreens will remain potent for up to 3 yrs per FDA regulations, most include expiration dates. Just make sure to check the formula and smell before you use it to ensure it is still good to use.
Avoid oxybenzone, a synthetic estrogen that penetrates the skin and can create a hormone imbalance or or trigger allergic skin reactions.
Reapply sunscreen approximately every two hours, or after swimming or sweating, according to the directions on the bottle.
Avoid sun exposure, especially during the hours of 10 a.m. and 4 p.m., when UV rays are strongest.
SPF needs a good 20 minutes to sink in before your skin is completely protected from UV rays.
Most people don’t realize that the proper amount of sunscreen for an adult full-body application is 2 to 3 tablespoons — or about one shot glass full.