UVA AND UVB
Two types of ultraviolet (UV) rays penetrate the atmosphere and can affect all parts of the body—from the back of your neck to an exposed ankle to the skin beneath your shirt. As much as 95 percent of UV radiation reaching the earth comes from UVA rays, which are less intense than UVB rays but 30 to 50 times as prevalent. UVA rays are present across the country during all daylight hours throughout the year, with fairly equal intensity—even when it’s cloudy! UVA are the dominant tanning rays, with indoor tanning booths emitting UVA in doses as high as 12 times that of the sun.
While UVB rays also contribute to the tanning process, these rays are the primary cause of sunburn and skin reddening. Although intensity varies from place to place— and depending on time of day—UVB rays hit the US most significantly from mid-morning (10 a.m.) to late afternoon (4 p.m.). You can still get sunburned at high altitudes throughout the rest of the year, however, as well as on reflective surfaces like snow and ice. And both UVA and UVB rays contribute to some of our worst skin woes, including visible signs of aging, premature wrinkling, and skin cancer.
The most obvious way to defend against these conditions is to wear sunscreen—but many people are concerned that topically applying certain formulas, particularly those with chemicals, might do more harm than good. Here are five reasons to slather on that lotion as your gear up for summer, as well as our favorite natural sunscreens that will protect skin from the outside in.