Summer begins, according to the calendar, on Wednesday and that means most of us will be spending more time outside in the sun.
April Farrell, MD, Gundersen dermatologist, discussed how to keep our skin safe in the sun in this week's Medical Monday report.
SPF, stands for sun protection factor, and is a measure of how well a sunscreen guards against ultraviolet B (UVB) rays, the chief cause of sunburn and a contributor to skin cancer.
Assuming you use it correctly, if you'd burn after 10 minutes in the sun, an SPF 30 protects for about 5 hours. But the intensity of UVB rays varies throughout the day and by location, and all sunscreens must be reapplied every 2 hours you're in the sun.
The Food and Drug Administration has yet to decide whether it will stop allowing sunscreen manufacturers to market their products with SPF numbers higher than 50, even though sunscreens with 90 and 100 SPF coverage often offer similar protection as those that are SPF 50.