Is your sunscreen actually working?
Diffuse, Block or Screen
Sun Damage Protection
The three mantras of sun protection are:
Diffuse your light and sun exposure whenever possible.
Block and Screens with effective SPF, Visible light, LED, and Infrared Light protection
Brace your skin against free radical damage
How to Best Guard Against Light Exposure
Hats, protective clothing, and proper eye wear.
What Does UVA and UVB Mean to my skin?
The rays of the sun damage the skin by exposing it to UVA and UVB rays. UVB has always been the big bad UV to avoid, the "B" we nickname for the "Burn", but "A" could be thought of as the "Aging" UV. And as for the SPFs. The FDA has approved 17 agents for use in sunscreens that will provide SPF. Some are organic or the chemical sunscreens which absorb the UV before it strikes and others are the inorganic literally forming a physical barrier that also works by being strongly reflective. And lots of products have a bit of both. You can read an entire review the UVA and UVB at the Skin Cancer Foundation.
So back to SPF, what exactly are you getting. Well, first of all there is no known UVA rating for protection. No SPF grading system is for UVA. So all of the grading is for UVB. And the ratings are for "amount of time, relatively, it takes you to burn.." A very general term. So if you normally burn in 10 minutes and you are wearing SPF 30, you should be able to stay in the sun for 300 minutes before you burn. But that doesn't mean that you haven't absorbed a lot of heat during that time, nor that the product has stayed on that long, nor does it really mean that you really took that long to burn in the first place. Nor does an alarm sound when you have incomplete or inconsistent application, are at altitude, or exposed to conditions like wind, or taking medication that can compound the effects of the sun. Nor do these figures correct for age or ethnicity, that's basically up to us, so these products have a lot to be desired in their labeling. Not only that but these are statistics. So that for SPF of 50 vs SPF of 100: significantly less people will burn at 100 than 50 if kept on for the same amount of time.
And the concern over the lack of UVA protection was so great that last July 3, 2009 caused a lot of alarm when they reported that three of five brand-name products "either don't protect the skin from sun damage sufficiently, contain hazardous chemicals, or both, according to a report by the watchdog organization Environmental Working Group."
And if you want to see just how smart you really are about this:
How about the sun safety IQ