What is the SPF system?

The Sun Read more from
Chapter Weather in Space

The Sun protection factor (or SPF) rates sunscreens based on how much they shield your skin from ultraviolet radiation. Depending on your skin pigmentation and age, an SPF rating of somewhere between 30 and 50 is usually recommended for any lengthy amount of time in the Sun, and children, especially, should use higher SPF-rated sunscreens. Sunscreen should be applied about a half hour before going outside. If you are unsure about what sunscreen to use, a good idea is to ask your physician or pharmacist.


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