Why do we have to wear sunscreen? - Kevin P. Boyd

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You already know that a trip to the beach can give you a nasty sunburn, but the nitty gritty of sun safety is actually much more complex. Wrinkle-causing UVA rays and burn-inducing UVB's can pose a serious risk to your health (and good looks). So what can you do? Kevin P. Boyd makes the case to slap on some physical or chemical SPF daily.

Lesson by Kevin P. Boyd, animation by Andrew Foerster.

Most of us think of the Sun as our friend.

It helps plants grow,

keeps us warm,

and who doesn't love to lie on the beach on a sunny day?

But for all of it's good qualities,

the Sun can also be harmful in large amounts.

That's why we invented sunscreen.

The purpose of sunscreen is to shield the body

from the Sun's ultraviolet rays,

which have several harmful effects,

including sunburn,

aging,

and skin cancer promotion.

These rays are separated

by their different wave lengths,

into types such as UVA

and UVB,

which exert a variety of effects in the skin

due to the absorption patterns of chromophores,

the parts of the molecules

responsible for their color.

The primary two chromophores are hemoglobin,

found in our red blood cells,

and melanin, which gives our skin its pigment.

We know that UVB rays cause the skin to burn.

The role of UVA rays is less well understood

and appears to have an effect

on our tanning response,

carcinogenesis,

and aging.

So, how does the sunscreen protect us from these rays?

There are two basic types of sunscreen,

physical and chemical blockers.

Physical blockers, like zinc oxide

or titanium dioxide,

reflect the Sun's rays by acting as a physical barrier.

If you've seen lifeguards with noses covered in white,

then you know what this looks like.

The same ingredients are primary components

of diaper creams,

where the goal is also to create a physical barrier.

Historically, they haven't always been easy to apply

and were conspicuously visible on the skin,

but new formulations have made this less of an issue.

Chemical blockers, on the other hand,

absorb the Sun's rays.

They deteriorate more quickly than physical sunscreens

because their ability to absorb the Sun diminishes.

Generally, these are more transparent

when rubbed on the skin,

but some people develop allergric reactions

to some of the chemicals.

Regardless of the type of sunscreen,

all are subjected to testing

to determine their sunburn protection factor,

or SPF.

This is essentially a measure of the protection

that the sunscreen will provide from UVB rays

before one begins to burn.

But even if you don't burn,

you still need to use sunscreen

because unless you live in a cave,

you're not immune to the effects of the Sun.

It is true that darker skinned people

and those who tan easily

have more built-in protection from sunburns,

but they are still vulnerable

to the effects of UVA.

Children under the age of six months,

on the other hand,

should have almost no sun exposure

as their protective mechanisms

are not fully functioning,

and their skin is more likely to absorb

any sunscreen that is applied.

Wearing sunscreen helps protect

against the development of all three types of skin cancer:

basal cell carcinoma,

squamous cell carcinoma,

and melanoma.

On a daily basis, the DNA in your cells

is developing mutations and errors

that are generally handled

by machinery within your cells,

but ultraviolet rays from the Sun lead to mutations

that the cell may not be able to overcome,

leading to uncontrolled growth

and eventual skin cancer.

The scariest thing about this

is that usually you can't even see it happening

until its too late.

But if these concrete risks to your health

are not enough to convince you to use sunscreen,

there are aesthetic reasons as well.

Along with cigarette smoking,

sun damage is the leading cause of premature aging.

Photoaging from chronic sun exposure

leads to a loss of elasticity in the skin,

in other words, making it look saggy.

Take a look at this truck driver

who's left side was chronically exposed to the sun

and notice the difference.

This is an important point.

Car windows block UVB, the burn rays,

but not UVA, the aging rays.

It is recommended to use sunscreen daily,

but you should pay special attention

before prolonged sun exposure

or when at the beach

or among snow

since the reflectivity of water and ice

amplifies the Sun's rays.

For these cases, apply about an ounce

fifteen to thirty minutes before you go out

and once again soon after you get outside.

After that, you should reapply it every two to three hours,

especially after swimming or sweating.

Otherwise you should wear protective clothing

with ultraviolet protection factor, or UPF.

Stay in shaded areas,

such as under trees or an umbrella,

and avoid the sun at the peak hours

of 10 a.m. to 4 p.m.

And what's the best kind of sunscreen?

Everyone will have their preference,

but look for the following things:

broad spectra,

SPF of at least 30,

and water-resistant.

A light moisturizer with SPF 30

should be good for daily use.

Take note if you decide to use a spray.

They take several coats to effectively cover your skin,

like painting a wall with a spray can

versus a paint brush.

So, enjoy the sun,

but enjoy it with sunscreen.