Hi, I'm Louise from the Ontario Science Centre.
It's summer, the sun is shining and everybody wants to head out to enjoy the
great weather. But before you head out, doctors warn
that you need some kind of sun protection.
And why is that? Well, the thing is, sunlight contains ultraviolet light,
which is just outside of the visible light spectrum what the human eye can
perceive. So we can't see ultraviolet light but it
has the energy to damage living cells. So when you go
out and you're unprotected, it will damage your living skin tissue. And this damage will accumulate through your childhood
and teen years and that damage doesn't show up until
later in life. But the thing is, sun damage is associated with
increased risk for skin cancer, so in this case
an ounce of prevention is worth a pound of cure.
So what can we do? One option for sun protection
is to use a sunscreen. Now, there's two types of sunscreen ingredients that
are available. The first group of ingredients are the synthetic organic
chemicals. These are human-made, carbon-based chemicals
that have the ability to absorb the energy of incoming
ultraviolet radiation and disperse it in the form of infrared
radiation,also known as heat energy. Here's an example.
Here, this is avobenzone and we can find it here in
this sunscreen spray along with some other synthetic organic chemicals like
octisalate and octocrylene. The other group of chemicals are the mineral oxides .
Here's an example of a mineral oxide cream. So the oxides that we can use are zinc
oxide and titanium dioxide. Now mineral oxides
are able to absorb the energy of ultraviolet radiation and they're
also able to scatter and reflect a small portion of that incoming light.
With both types of sunscreen ingredients, they have to be applied to the skin
about 15 minutes before sun exposure and that allows the sunscreen formulation to
dry down and form a uniform coat on the skin so
you don't get patchy coverage. Sun Protection Factor
or SPF for short is an attempt to quantify how much protection a sunscreen can
provide. Many people think that SPF is an
approximation of how much time that you can spend
in the sun before getting a sunburn. So, for example,
SPF 30 means that you could spend 30 times longer in the sun before
getting a sunburn. But this is not true. SPF is actually
an estimate of how much uv radiation a sunscreen can absorb and thus prevent
from reaching living skin tissue. And the amount of time that you spend in
the sun is just one factor that determines that amount.
The other factor is light intensity, and that's affected by
time of year, time of day, weather conditions, and how
far away you might be from the equator. Because most sunscreens become less
visible or invisible once applied to the skin,
it's really difficult to visualize the amount of uv radiation
that you have been exposed to. One way to do it is to wear beads or stickers that
contain a photo sensitive dye that changes color
upon exposure to uv radiation. But just be aware
these items can't tell you if you have applied enough
everywhere where it's needed, if you have even coverage,
or if you missed a spot. Doctors recommend using a broad spectrum
sunscreen that is rated SPF 30 or higher. You might think the higher the number,
the better the protection, but actually SPF 50 can filter out about
98% of incoming uv radiation compared to SPF 30, which can filter out about 96.7 percent of incoming uv radiation.
So it's only a marginal difference. Sunscreens have to be applied
very generously. TheCcanadian Dermatology Association advises application of
one palm full for each arm and for each leg.
In practice, that's about 30 millilitres or two tablespoons
for the arms and legs and no matter what the SPF rating is, all sunscreens will wear off eventually,
especially if you happen to be sweating or if you go swimming.
So they need to be reapplied every two hours.
Sunscreens will eventually wash off and make their way into nearby bodies of
water. There's mounting concern over the effect
of sunscreens on the organisms that live in and around aquatic environments.
There's evidence suggesting that these synthetic sunscreens,
oxybenzone and benzophenone 2 are toxic to coral reefs
and are compounding the effects of climate change, which is causing the
oceans to become warmer and more acidic. All of these factors are leading to
coral reefs bleaching and dying. There's also concern that
nanoparticles of the mineral oxides may be damaging to aquatic ecosystems.
For sun protection, sunscreen is just one option that should be combined with
other actions. Before you head out, check the weather
report and look for the predicted uv index. If it's three or higher, you'll
need some form of sun protection. Try to avoid sun exposure between the
hours of 11 am and 3 pm, especially around noon. That's
when the sun's rays are at their most intense.
Along with sunscreen, think about wearing your shade and that means
long sleeves and pants. There's UV protective clothing,
like this jacket. You can also wear clothing
that's made out of a tightly woven, opaque fabric.
Wear a broad brimmed hat. Think about wearing UV-protective sunglasses, You can
also carry a parasol or umbrella.
We're really interested to know how you're practicing sun safety, so
please send in your photos and comments. Thanks so much for watching.