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How does Sunscreen work?

Updated: Dec 16, 2020

I am sure you've heard that wearing sunscreen is imperative, not least from me.

But have you ever wondered how sunscreens actually works?

You will see the difference between physical and chemical sunscreens, helping you pick the perfect type of sunscreen for you.

Why is it important to wear sunscreen?

Sunscreens are cosmetics protect our skin from harmful UV light.

They block the UV light from coming into contact with our skin, so that our skin does not burn and cause pre-mature ageing of the skin.

Types of UV rays

There are three different types of UV rays:

UVA rays

'Ageing rays'

This specific type of ultraviolet light is linked to the ageing of the skin.

Due to their long wavelength, they penetrate through to the second layer of the skin.

Used in modern tanning beds.

UVB rays

'Burning rays'

This is the ultraviolet frequency which has the ability to burn your skin.

They only interact with the top layer of the skin.

These are the rays which are heavily linked to skin cancer.

UVC rays

You don't have to worry about these rays, as the ozone protects you from this frequency of rays.

These have the shortest frequency.

Usually used in old-school tanning beds.

Physical sunscreens

These sunscreens contains ingredients which physically block UV rays.

They are made up of mineral or inorganic ingredients which reflect UV rays away from the skin.

Ingredients include:

  1. Zinc oxide

  2. Titanium dioxide

  3. Oxybenzone

Pros of physical sunscreens

  • Safe for use during pregnancy and for babies

  • Less likely to irritate the skin

  • Better for people with heat sensitivity

Cons of physical sunscreens

  • Can be rubbed off and sweated off so application should be more frequent

  • Can appear white or chalky, especially on deeper skin tones

  • A thick layer needs to be applied for it to be very effective

Chemical sunscreens

These sunscreens contain ingredients which dissipate UV rays from light energy into heat energy on the skin.

Ingredients include:

  1. Avobenzne

  2. Dioxybenzone

  3. Octocrylene

  4. Octinoxate

  5. Mexoryl SX

Mexoryl SX is a rather recent sunscreen ingredient and works wonders against UVA rays. People are trying to get a hold of sunscreens containing Mexoryl SX as it prevents skin ageing from the sun.

Pros of chemical sunscreens

  • Thinner in consistency, easily spreadable

  • Easily combines with other products in your skincare routine

  • You don't need to apply as much product

Cons of chemical sunscreens

  • Can be irritating to the skin and eyes

  • Only becomes effective 20 minutes after application

  • Can clog pores and increase breakouts

Which are the best sunscreens?

The best sunscreens protect you from both UVA and UVB rays effectively.

But as mentioned above, there are both pros and cons to physical and chemical sunscreens.

I would suggest you apply a chemical sunscreen as part of your daily routine which mainly protect your face from UVA rays. This way, you will not develop premature wrinkles.

However, during the summer months, I use a physical blocker on my body - as I do not want to over-sensitise my skin.

If you're wondering what an SPF is, click here to find out.

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