Placeholder Image

Subtitles section Play video

  • Sunscreen comes in many forms,

  • each with its own impacts on your body and the environment.

  • With so many options,

  • how do you choose which sunscreen is best for you?

  • To answer that question,

  • we first have to understand how sunscreens work.

  • Sunlight is composed of electromagnetic waves

  • and is our primary source of ultraviolet radiation,

  • which has a shorter wavelength than visible light and carries more energy.

  • UVA,

  • UVB,

  • and UVC are classified according to their wavelengths.

  • Short wavelength UVC never reaches the Earth's surface,

  • but UVB and UVA do.

  • Medium wavelength UVB rays can enter the skin's superficial layers

  • and long length UVA rays can penetrate into the deeper layers.

  • UVB in small amounts actually helps us make vitamin D,

  • which enables our bodies to build and maintain strong bones.

  • However, prolonged exposure to UVA and UVB can damage DNA,

  • age your skin,

  • and promote the development of potentially deadly skin cancer.

  • Sunscreen protects your skin either physically by deflecting UV rays

  • with an inorganic blocker like zinc oxide or titanium dioxide,

  • or chemically by using carbon-based compounds to absorb UV photons

  • that are then harmlessly dissipated as heat.

  • So, what differentiates one sunscreen from another?

  • When we choose a sunscreen,

  • we can compare application method,

  • the SPF,

  • and the active ingredients.

  • Sprays can be convenient to put on, especially when you're wet,

  • but a recent study found that most people don't apply a thick enough layer

  • to get full protection.

  • And the possible health risks of inhaling sunscreen compounds from a spray cloud

  • might make you consider reaching for that bottle of lotion instead.

  • Opt for a sunscreen with an SPF of at least 15, although 30 is better.

  • SPF is a nonlinear scale of how much UVB radiation is needed

  • to give protected skin a sunburn.

  • SPF 15 does a pretty good job by blocking 93% of UVB rays.

  • You get a slight increase as SPF goes up,

  • with SPF 30 blocking 97%,

  • and 50 blocking 98%.

  • SPF is based on the quantity of solar exposure.

  • So how much time you have before you start to burn

  • really depends on a long list of factors,

  • including your genetics,

  • and when, where, and how you spend your time in the sun.

  • Even though US marketed sunscreens have been deemed safe by the FDA,

  • scientists are still researching the effects of many active ingredients

  • on the human body.

  • So if you're worried about potential irritants,

  • look for mineral-based formulas with zinc oxide or titanium dioxide.

  • Even though they may go on a bit thick at first,

  • they're less irritating than carbon-based chemical sunscreens.

  • These mineral-based sunscreens are preferential for the environment, too.

  • If you plan on catching rays while splashing in a river or the ocean,

  • keep in mind that carbon-based chemical sunscreens

  • can harm marine life.

  • Take coral reefs for example.

  • Although they cover less than 1% of the Earth's underwater surface,

  • they're home to nearly 25% of all fish species,

  • making them the most diverse and productive marine ecosystems.

  • Research shows that carbon-based chemical sunscreen ingredients,

  • like oxybenzone, butylparaben, octinoxate, and 4MBC

  • contribute to a stress condition called coral bleaching in corals,

  • which are living creatures.

  • Exposure to these organic compounds

  • results in the death of the coral's symbiotic algae.

  • In addition to providing a reliable food source,

  • these algae give coral their brilliant rainbow of colors.

  • Without them, corals turn a bleached white

  • and are susceptible to disease and possibly death.

  • And once the coral dies,

  • the entire reef ecosystem is not far behind.

  • So you're now ready to make an informed choice when picking out your next sunscreen.

  • SPF is clearly labeled on the front.

  • On the back under "active ingredients,"

  • you can find whether zinc oxide,

  • titanium dioxide,

  • and those coral-harming components are present.

  • Taking a bit more time to check can be well worth it

  • for both you and the environment.

Sunscreen comes in many forms,

Subtitles and vocabulary

Operation of videos Adjust the video here to display the subtitles

B2 TED-Ed sunscreen spf coral titanium dioxide based

【TED-Ed】Which sunscreen should you choose? - Mary Poffenroth

  • 3234 293
    Jamie 榕 posted on 2016/08/21
Video vocabulary