The SPF – or “sun protection factor” – number on a sunscreen’s label is a guide to the product’s level of sunburn protection.
In general, the SPF number indicates how much longer you can stay exposed to the sun before getting sunburned when wearing sunscreen, as opposed to without sunscreen.
For example, it takes 15 times longer to burn with sunscreen SPF 15 than without sunscreen. However, whatever the SPF number, sunscreen should be reapplied at least every 2 hours after swimming or sweating, and towel drying.
UV rays are usually strongest from 10 a.m. to 2 p.m., but remember, the longer you are out in the sun, the more exposed you are to UV rays!
The sun's UV rays are strongest during the summer months, but UV rays reach the Earth every day, year-round, even in winter!
Surfaces like concrete, sand, water and snow can reflect 85% of the sun's rays back at you.
UV rays are strongest if you are near the Equator, and the higher the elevation, the greater your exposure.
If you have fair skin, as well as light-colored eyes and hair, your're likely to burn more easily when exposed to UV rays.
For protection against UVB and UVA rays, look for the words "broad spectrum" on the product label.
Many dermatologists recommend using a product with minimum SPF 30, which can help protect you from approximately 97% of the sun’s harmful rays.
Other factors to consider may include medications, medical conditions, or special circumstances (i.e. recent surgery). The above list is not exhaustive so please consult with your dermatologist or general practitioner before going in the sun.