How does sunscreen work?

How does sunscreen work?

Don't get burnt this summer!

The science of summer skincare...
Lobster red skin is difficult look to pull off, but sunburn and other UV damage can easily be avoided with a bit of a common sense and a good splodge of sunscreen.

What is ultraviolet radiation?

Ultraviolet (UV) radiation has a shorter wavelength than visible light. Much of the energy emitted by the sun is in the form of UV radiation. Luckily our planet's atmosphere - especially the ozone layer - does a good job of filtering out most of the UV radiation before it reaches us.

Astronauts aren't protected by the atmosphere, so UV is a huge hazard for them - if their skin was exposed they would be burnt in a matter of seconds. Even down on Earth it makes sense to be cautious. UV rays can cause sunburn as well as more permanent damage to your skin or eyes.

Astronaut sun_95795931

Space suits protect astronauts from UV rays

How much UV radiation you're exposed to when out and about depends on several factors:

  • proximity to the equator
  • altitude
  • time of day
  • season
  • cloudiness.
If you're planning a lunchtime picnic on Mount Kilimanjaro, you'd better make sure you pick a shady spot!

Spectrum from x-rays to infrared

UV radiation is divided into categories according to its wavelength (see above). UV-B radiation is to blame for sunburn. UV-As are responsible for long term skin damage. Thankfully, sunscreen can protect us from both these invisible enemies.

Stopping UV in its tracks

Sunscreens help to filter out UV radiation using two main types of active ingredients. Inorganic particles, such as titanium dioxide or zinc oxide, form a physical barrier which reflects or scatters UV waves. Organic particles absorb UV rays and release their energy as heat.

The light-reflecting inorganic compounds meant that early sunscreens looked just like white paint. Nowadays, nanotechnology has made it possible to produce completely clear sunscreens which still fend off UV rays just as effectively. They contain the same ingredients as traditional formulations, but the inorganic particles are so small that they are invisible.

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