WEBVTT

00:00:06.786 --> 00:00:09.410
Most of us think of the Sun as our friend.

00:00:09.410 --> 00:00:10.854
It helps plants grow,

00:00:10.854 --> 00:00:11.862
keeps us warm,

00:00:11.862 --> 00:00:15.035
and who doesn't love to lie on the beach on a sunny day?

00:00:15.035 --> 00:00:16.688
But for all of it's good qualities,

00:00:16.688 --> 00:00:19.664
the Sun can also be harmful in large amounts.

00:00:19.664 --> 00:00:22.417
That's why we invented sunscreen.

00:00:22.417 --> 00:00:24.501
The purpose of sunscreen is to shield the body

00:00:24.501 --> 00:00:26.680
from the Sun's ultraviolet rays,

00:00:26.680 --> 00:00:28.220
which have several harmful effects,

00:00:28.220 --> 00:00:29.191
including sunburn,

00:00:29.191 --> 00:00:29.839
aging,

00:00:29.839 --> 00:00:32.138
and skin cancer promotion.

00:00:32.138 --> 00:00:33.472
These rays are separated

00:00:33.472 --> 00:00:35.112
by their different wave lengths,

00:00:35.112 --> 00:00:36.725
into types such as UVA

00:00:36.725 --> 00:00:38.311
and UVB,

00:00:38.311 --> 00:00:40.524
which exert a variety of effects in the skin

00:00:40.524 --> 00:00:43.305
due to the absorption patterns of chromophores,

00:00:43.305 --> 00:00:44.319
the parts of the molecules

00:00:44.319 --> 00:00:46.065
responsible for their color.

00:00:46.065 --> 00:00:48.568
The primary two chromophores are hemoglobin,

00:00:48.568 --> 00:00:50.213
found in our red blood cells,

00:00:50.213 --> 00:00:53.210
and melanin, which gives our skin its pigment.

00:00:53.210 --> 00:00:56.193
We know that UVB rays cause the skin to burn.

00:00:56.193 --> 00:00:58.873
The role of UVA rays is less well understood

00:00:58.873 --> 00:01:00.414
and appears to have an effect

00:01:00.414 --> 00:01:02.037
on our tanning response,

00:01:02.037 --> 00:01:03.128
carcinogenesis,

00:01:03.128 --> 00:01:04.460
and aging.

00:01:04.460 --> 00:01:07.122
So, how does the sunscreen protect us from these rays?

00:01:07.122 --> 00:01:09.088
There are two basic types of sunscreen,

00:01:09.088 --> 00:01:11.790
physical and chemical blockers.

00:01:11.790 --> 00:01:13.342
Physical blockers, like zinc oxide

00:01:13.342 --> 00:01:15.410
or titanium dioxide,

00:01:15.410 --> 00:01:18.399
reflect the Sun's rays by acting as a physical barrier.

00:01:18.399 --> 00:01:20.601
If you've seen lifeguards with noses covered in white,

00:01:20.601 --> 00:01:22.229
then you know what this looks like.

00:01:22.229 --> 00:01:24.355
The same ingredients are primary components

00:01:24.355 --> 00:01:25.536
of diaper creams,

00:01:25.536 --> 00:01:28.230
where the goal is also to create a physical barrier.

00:01:28.230 --> 00:01:30.534
Historically, they haven't always been easy to apply

00:01:30.534 --> 00:01:33.160
and were conspicuously visible on the skin,

00:01:33.160 --> 00:01:36.161
but new formulations have made this less of an issue.

00:01:36.161 --> 00:01:37.934
Chemical blockers, on the other hand,

00:01:37.934 --> 00:01:39.813
absorb the Sun's rays.

00:01:39.813 --> 00:01:42.371
They deteriorate more quickly than physical sunscreens

00:01:42.371 --> 00:01:46.099
because their ability to absorb the Sun diminishes.

00:01:46.099 --> 00:01:48.024
Generally, these are more transparent

00:01:48.024 --> 00:01:49.494
when rubbed on the skin,

00:01:49.494 --> 00:01:51.632
but some people develop allergric reactions

00:01:51.632 --> 00:01:53.522
to some of the chemicals.

00:01:53.522 --> 00:01:55.345
Regardless of the type of sunscreen,

00:01:55.345 --> 00:01:56.911
all are subjected to testing

00:01:56.911 --> 00:01:59.263
to determine their sunburn protection factor,

00:01:59.263 --> 00:02:00.663
or SPF.

00:02:00.663 --> 00:02:02.431
This is essentially a measure of the protection

00:02:02.431 --> 00:02:05.301
that the sunscreen will provide from UVB rays

00:02:05.301 --> 00:02:07.009
before one begins to burn.

00:02:07.009 --> 00:02:08.303
But even if you don't burn,

00:02:08.303 --> 00:02:09.895
you still need to use sunscreen

00:02:09.895 --> 00:02:11.684
because unless you live in a cave,

00:02:11.684 --> 00:02:14.496
you're not immune to the effects of the Sun.

00:02:14.496 --> 00:02:16.492
It is true that darker skinned people

00:02:16.492 --> 00:02:17.604
and those who tan easily

00:02:17.604 --> 00:02:20.323
have more built-in protection from sunburns,

00:02:20.323 --> 00:02:21.992
but they are still vulnerable

00:02:21.992 --> 00:02:23.822
to the effects of UVA.

00:02:23.822 --> 00:02:25.808
Children under the age of six months,

00:02:25.808 --> 00:02:26.660
on the other hand,

00:02:26.660 --> 00:02:28.532
should have almost no sun exposure

00:02:28.532 --> 00:02:29.951
as their protective mechanisms

00:02:29.951 --> 00:02:31.489
are not fully functioning,

00:02:31.489 --> 00:02:33.075
and their skin is more likely to absorb

00:02:33.075 --> 00:02:35.454
any sunscreen that is applied.

00:02:35.454 --> 00:02:37.012
Wearing sunscreen helps protect

00:02:37.012 --> 00:02:40.300
against the development of all three types of skin cancer:

00:02:40.300 --> 00:02:42.341
basal cell carcinoma,

00:02:42.341 --> 00:02:44.216
squamous cell carcinoma,

00:02:44.216 --> 00:02:45.843
and melanoma.

00:02:45.843 --> 00:02:47.969
On a daily basis, the DNA in your cells

00:02:47.969 --> 00:02:49.925
is developing mutations and errors

00:02:49.925 --> 00:02:51.596
that are generally handled

00:02:51.596 --> 00:02:53.681
by machinery within your cells,

00:02:53.681 --> 00:02:57.163
but ultraviolet rays from the Sun lead to mutations

00:02:57.163 --> 00:02:59.223
that the cell may not be able to overcome,

00:02:59.223 --> 00:03:00.859
leading to uncontrolled growth

00:03:00.859 --> 00:03:02.690
and eventual skin cancer.

00:03:02.690 --> 00:03:04.191
The scariest thing about this

00:03:04.191 --> 00:03:06.456
is that usually you can't even see it happening

00:03:06.456 --> 00:03:08.162
until its too late.

00:03:08.162 --> 00:03:10.584
But if these concrete risks to your health

00:03:10.584 --> 00:03:13.613
are not enough to convince you to use sunscreen,

00:03:13.613 --> 00:03:16.119
there are aesthetic reasons as well.

00:03:16.119 --> 00:03:17.603
Along with cigarette smoking,

00:03:17.603 --> 00:03:20.747
sun damage is the leading cause of premature aging.

00:03:20.747 --> 00:03:22.748
Photoaging from chronic sun exposure

00:03:22.748 --> 00:03:25.511
leads to a loss of elasticity in the skin,

00:03:25.511 --> 00:03:28.330
in other words, making it look saggy.

00:03:28.330 --> 00:03:29.434
Take a look at this truck driver

00:03:29.434 --> 00:03:32.171
who's left side was chronically exposed to the sun

00:03:32.171 --> 00:03:33.911
and notice the difference.

00:03:33.911 --> 00:03:35.848
This is an important point.

00:03:35.848 --> 00:03:38.745
Car windows block UVB, the burn rays,

00:03:38.745 --> 00:03:41.691
but not UVA, the aging rays.

00:03:41.691 --> 00:03:44.276
It is recommended to use sunscreen daily,

00:03:44.276 --> 00:03:45.747
but you should pay special attention

00:03:45.747 --> 00:03:47.694
before prolonged sun exposure

00:03:47.694 --> 00:03:48.904
or when at the beach

00:03:48.904 --> 00:03:50.119
or among snow

00:03:50.119 --> 00:03:52.415
since the reflectivity of water and ice

00:03:52.415 --> 00:03:54.758
amplifies the Sun's rays.

00:03:54.758 --> 00:03:56.834
For these cases, apply about an ounce

00:03:56.834 --> 00:03:58.956
fifteen to thirty minutes before you go out

00:03:58.956 --> 00:04:01.161
and once again soon after you get outside.

00:04:01.161 --> 00:04:04.325
After that, you should reapply it every two to three hours,

00:04:04.325 --> 00:04:06.909
especially after swimming or sweating.

00:04:06.909 --> 00:04:08.508
Otherwise you should wear protective clothing

00:04:08.508 --> 00:04:12.166
with ultraviolet protection factor, or UPF.

00:04:12.166 --> 00:04:13.250
Stay in shaded areas,

00:04:13.250 --> 00:04:15.052
such as under trees or an umbrella,

00:04:15.052 --> 00:04:16.637
and avoid the sun at the peak hours

00:04:16.637 --> 00:04:18.603
of 10 a.m. to 4 p.m.

00:04:18.603 --> 00:04:20.985
And what's the best kind of sunscreen?

00:04:20.985 --> 00:04:22.544
Everyone will have their preference,

00:04:22.544 --> 00:04:24.674
but look for the following things:

00:04:24.674 --> 00:04:25.752
broad spectra,

00:04:25.752 --> 00:04:27.859
SPF of at least 30,

00:04:27.859 --> 00:04:29.361
and water-resistant.

00:04:29.361 --> 00:04:31.365
A light moisturizer with SPF 30

00:04:31.365 --> 00:04:33.521
should be good for daily use.

00:04:33.521 --> 00:04:35.495
Take note if you decide to use a spray.

00:04:35.495 --> 00:04:38.416
They take several coats to effectively cover your skin,

00:04:38.416 --> 00:04:40.327
like painting a wall with a spray can

00:04:40.327 --> 00:04:41.967
versus a paint brush.

00:04:41.967 --> 00:04:43.831
So, enjoy the sun,

00:04:43.831 --> 00:04:46.223
but enjoy it with sunscreen.