“Dr. Dao explained, “SPF 30 extends the time needed by 30-fold before the skin turns red from sun exposure. SPF 50 extends the time needed by 50-fold.””
“Dr. Dao also said that UVA makes up about 95 percent of the sun’s UV radiation, which reaches Earth and contributes to photodamage and skin cancers. ... SPF 30 blocks 97 percent of UVB, SPF 50 blocks…”
“Dr. Dao also said that UVA makes up about 95 percent of the sun’s UV radiation, which reaches Earth and contributes to photodamage and skin cancers. ... sunscreens wear out at the same rate and need …”
