hi it's Michelle from lab muffin beauty science chemistry PhD skincare nerd and
pigmentation monster my skin loves producing pigment and I live in sunny
Australia so obviously sun protection is one of my
big obsessions a good sunscreen is one of the most important things you can use
to prevent pigmentation so things like sunspots and to help you fade acne marks
to understand sunscreen you need to know about UVA and so that's the topic of
today's video if you like this sort of video give it a thumbs up subscribe to
my channel and make sure you hit the notification button so that you don't
miss out on any videos so first up what is UVA the Sun emits 3 main types of
light there's UV which is ultraviolet there's visible light which we can see
and there's infrared or IR I've talked about what visible light can do to your
skin in a previous video and today we're going to be focusing on the Big Kahuna
which is UV UV light is divided into 3 major types this is according to how
much energy they have which is inversely proportional to their wavelength in
other words the shorter the wavelength the higher the energy the shortest
wavelength highest energy light is UVC this has wavelengths of 100 to 280
nanometers since it's the most energetic it's the most harmful luckily it's also
the least penetrating it's almost completely blocked by the atmosphere and
the ozone layer so you don't really need to worry too much about it the next type
is UVB which is from 280 nanometers to 350 nanometers this is probably the type
of UV you've heard about the most about 90% of the UVB that the Sun produces
gets absorbed by the ozone layer which is 25 kilometers above the Earth's
surface this means that for Australians and other people who live close to the
South Pole it's a bigger issue because there's an ozone hole above Antarctica
which means that it lets in more UV light we also have really nice sunny
weather which means we're more likely to be outside uvb causes
sunburns and skin cancer but luckily it is mostly blocked by glass it's also
at the type of UV from the Sun that's involved in vitamin D production UVB is
the strongest in summer and in the middle of the day it's mostly what's
measured by the UV index which you can look up on your local weather site
finally we have UVA which is from about 350 to 400 nanometers this is the lowest
energy since it has the longest wavelength out of the different types of
UV light it has slightly shorter wavelengths than visible light UVA
penetrates the atmosphere better it's about 95 percent of the UV that reaches
the Earth's surface and it also penetrates deeper into your skin than
UVB the main impact of UVA on your skin is that it forms highly reactive free
radicals in your skin which have unpaired electrons this means that
they're really good at reacting with whatever's around like your DNA
UVA causes wrinkles and sun damage in your skin as well as deadly melanomas
it's the type of UV that you'll find in tanning beds and in black lights like
with UVB UVA levels depend on the time of day and the time of year but compared
to UVB it varies a lot less that means it's important to think about UVA
protection even during off-peak times as well UVA is further subdivided into uva1
and uva2. uva1 has longer wavelengths so it's above 340 nanometers
uva2 has shorter wavelengths it's closer to UVB and it's below 340
nanometers the main reason that UVA is less famous than UVB is that the dangers
of UVA weren't really known until relatively recently UVA effects are also
less immediate and they build up over time which means that it's sort of more
dangerous UVA's ability to penetrate deeper than UVB is also quite scary so
can penetrate through glass like the glass in your car side windows which is
why there's lots of asymmetric skin cancers emerging as well as asymmetric
wrinkle patterns so for example there's a famous photo of a truck driver he
drove a truck with the windows closed for about 28 years
the left side of his face received direct Sun the right side received
indirect Sun and you can see the massive difference in wrinkles even if you never
go to the beach and you never sunbathe you can still be affected by UVA it's
been estimated that about 80% of UVA damage actually comes from everyday life
so things like if you're walking around if you're driving or even if you're
sitting near a window now let's talk about sunscreen sunscreens almost always
have an SPF rating SPF stands for Sun Protection factor and the higher the SPF
the higher the protection you have against erythemal UV in other words UV
that causes your skin to burn SPF mostly measures protection against UVB although
shorter wavelengths of UVA will also cause burning about 9 to 20% of the
reaction if you have a sunscreen that only blocks against UVB you can actually
only get an SPF of 11 so there is UVA protection shown in the SPF the concept
of SPF was introduced in 1970 before all of this UVA research and so back then
scientists assumed that the only damage you could get to your skin was sunburn
and so that's what we protected ourselves against using sunscreens I've
talked more about SPF and whether or not higher SPFs are better in a different
video which I've linked below the problem with SPF is that it doesn't
really tell us that much about protection against longer wavelengths of
UV especially that UVA1 because we now know that UVA is also dangerous a
lot of countries have introduced other regulated terms in sunscreens that
describe how much UVA protection you're getting the most popular term is
something called broad spectrum there are a few slightly different ways of
measuring it the first method is using something called critical wavelength the
ability of the sunscreen to absorb UV is measured over different wavelengths and
for a sunscreen should be classified broad spectrum under this critical
wavelength criteria 90% of the total area under the absorption curve from 290
to 400 nanometers needs to be higher or equal to 317 nanometers the other
criteria that sometimes used for broad spectrum
is that the UVA protection factor has to be at least one third of the labeled SPF
in Australia in the EU both of these have to happen before a sunscreen gets
the broad spectrum rating in the u.s. broad spectrum sunscreen only needs the
critical wavelength criteria what this means is that in general a higher SPF is
going to give you better UVA protection Australian and EU sunscreens also give
you better guaranteed protection than a u.s. sunscreen that's because critical
wavelength does tell you about how wide the protection is so the broad spectrum
but it doesn't tell you that much info about how much protection you're getting
so in other words how strong that protection is one recent study did find
that US sunscreens give less protection than the sunscreens that require both
critical wavelengths and the one third SPF rule out of the 20 sunscreens tested
in this study 19 of them passed the US test but only 11 of them passed the EU
regulations with the extra 1/3 SPF requirement in some other countries
there's more specific UVA protection ratings
there's the PPD rating which stands for persistent pigment darkening this
measures how well a sunscreen protects you against a long-term tan that's
caused by UVA it's basically the equivalent of SPF but for UVA you'll
often find PPD ratings in European sunscreens there's also the PA rating
this is pretty similar to PPD but it uses plus signs and it's more popular in
Asian countries pa+ roughly translates to PPD 2 to 4, pa
double plus is PPD four to eight Pa triple plus is PPD eight to sixteen and
PA quadruple plus is PPD 16 and above unfortunately PA ratings don't tell you
how far above PPD 16 a sunscreen might be
another way of checking if you're getting good UVA protection is by
looking at the actual sunscreen ingredients most sunscreen ingredients
don't give great protection against longer wavelength UVA1 these curves
show you the protection ranges a higher line means higher protection but higher
percentages of that sunscreen ingredient will give you high protection so the
curve will go up so in terms of the relative protection it doesn't tell you
that much but it does tell you the breadth of protection the best uva1
protective ingredients for a long time were avobenzone and zinc oxide
avobenzone or BMDBM gives really good protection but it's photounstable which
means it breaks down in UV light so if it's on your skin it might stop
protecting you after a while unless it's being stabilized zinc oxide gives you
pretty flat protection throughout the different wavelengths but the problem is
it has really low protection which means that in a sunscreen what you need is a
really high percentage to lift that curve up and the problem with high
percentages is that a lot of the time the sunscreen feels gross and it gives
you a white cast you can see the white cast from these three sunscreens that
I've tried in the past
there are now some newest sunscreen ingredients that aren't really that new
but they give better protection and they avoid these issues with avobenzone
and zinc oxide they're longer-lasting because they're photostable
so they don't break down in UV and they're really effective so you don't
need to have too much in a sunscreen to give you that high protection
unfortunately most of these aren't available in the US unless you import
sunscreen from overseas these are the best longer-wavelength UVA protective
ingredients there's tinosorb s which is abbreviated as BEMT tinosorb M which is
MBBT Mexoryl XL which is DTS this is patented by L'Oreal and it's found
in La roche-posay products there's also uvinul a plus or DHHB mexoryl SX
or TDSA and there's Neo Heliopan AP or DPDT some of the older more
traditional sunscreen ingredients will also block against UVA too so for
example oxybenzone octocrylene and titanium dioxide how much protection you
get also depends a lot on the formulation so make sure you check the
regulated terms as well so the SPF the PPD the words broad-spectrum as well as
looking for these ingredients if you're interested in learning more about how to
pick a good sunscreen I've written a skincare guide which I've
linked below it also talks about how to pick a good cleanser and a good
moisturizer and how to set up a skincare routine
as you can probably guess by now sunscreens aren't the best type of sun
protection a lot of them don't have the best UVA protection you need to reapply
them regularly and it's really easy to miss a spot or apply too little but we
do have some other options as well some protective clothing is a really good
option so things like hats and sunglasses and shirts hats are really
good for protecting your scalp which is an area that most of us tend to miss you
should also try to stay in the shade and avoid sun exposure at peak times UV
that's been reflected off the surface onto you will still cause damage but a
lot less than the direct UV so you can see that from the truck-driver photo you
can also look into adding uva tints on windows that you go near a lot you don't
need to worry too much about the windshield because they're already
designed to block UVA I hope you like this video if you did please give it a
thumbs up and subscribe to my channel for more videos you can also follow me
on Instagram for more beauty science and check out my blog as well see you next
time for more nerdery