I am a Brit in Florida, which means I apply enormous amounts of sunblock
to stop me going as red as a lobster.
But here is something you might not know: the SPF factor on sunblock,
this 50 here, in this case—because I am very pale—was originally meant to be a multiplier.
The idea was... that if you burned in 10 minutes without sunblock,
that would multiply that by 50; you could manage 500 minutes in burning sun
before you actually got burned.
Now, the thing is: that's not actually true, because sunblock's a lot more complicated than that;
it requires differences depending on skin tone, on all sorts of things,
on your personal reaction.
Unless the sunblock is broad-spectrum, as this is, it doesn't cover against the more harmful effects
the long-term effects, not just turning red.
So, how do they test it?
Well, the way they test it is quite wonderful. The FDA in the US
for this—The Food and Drug Administration—requires what is known as
an "in vivo" test. Meaning it has to be done on an actual live volunteer,
which means that someone has, presumably, one arm covered in sunblock,
one arm - not, and then they are put under a test sun simulator until they burn to see what happens.
And, while it can, technically, get up to 100-200 times multiplier,
the FDA requires no more than 50. In Australia - no more than 30,
because anything more than that is considered confusing to people
who might think they can put sunblock on and stay out all day, every day, with no risk of skin cancer.
So, there you go. Sun Protection Factor - mostly a load of rubbish,
although, you should still wear it because otherwise,
well, you're going to end up like I'm going to look in probably a few hours' time.
Also, don't get it in your eyes!
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