Sunscreen SPF Meaning

Sunscreen is important to keep your skin beautiful, healthy and prevent premature ageing. The sunscreens absorb the UV rays from the sun which can make skin rough with freckles, spots and early wrinkles.

The sun's radiation contain ultra violet (UV) light in addition to other wavelengths. There are two types of UV rays, UVA and UVB. Both UVA and UVB can damage the skin.

The UVA rays can penetrate deep into the skin and can cause severe damage over a period of time. They play a role in the photo aging process. The UVB rays attack the outer skin layer and cause sunburn.

A sunscreen provides protection against the harmful sun radiation, if properly applied.




Types of Sunscreens

There are two types of sunscreens, which work by either reflecting or absorbing the sun's UV rays.

Physical Blockers or Physical Sunscreens

This type of sunscreen physically blocks the ultraviolet light providing a physical barrier between the skin and the sun. They contain inert mineral based non-chemical pigments or particles of size about 25 mm3 that reflect UV rays like a mirror. These are generally opaque, or becomes clear upon application.
Zinc oxide sunscreen and titanium dioxide sunscreens are physical sunscreens.
To make the sunscreen transparent, nowadays, nanosize particles are being used. These nanosize particles can enter the body through the skin, which may be harmful. Titanium dioxide can cause DNA damage in human cells.




Chemical Sunscreens

This type of sunscreen contains chemicals that absorb ultraviolet light radiation. Chemical sunscreens include Benzophenones, PABA and PABA (para amino benzoic acid), Cinnamates, Salicylates, Digalloyl trioleat, Menthyl anthranilate, etc.
Chemical sunscreens are powerful free radical generators, so they are not safe to use. Benzophenone is one of the most powerful free radical generators known.

These are known as organic sunscreens and are made of carbon and hydrogen. Organic does not mean that they are organically produced or naturally occurring in nature.

Physical sunscreens are more effective at overall sun protection as they absorb both UVA and UVB radiations (broad spectrum) and have anti-inflammatory properties making them good for sensitive skin and acne-prone skin. Zinc oxide lies on the skin without getting absorbed, so zinc oxide based sunscreen is considered as the safe and the best.

Sunscreen Ratings: Sunscreen SPF Ratings

Sunscreens are rated by Sun Protection Factor, SPF. SPF indicates the level of protection. The higher the SPF of a sunscreen the greater the level of protection it offers.

SPF is the relative time for developing redness upon exposure to UV radiation of sunscreen applied skin versus skin without the sunscreen. In other words, SPF refers to the amount of time you can stay in the sun without burning. A SPF 15 blocks about 95% of the UV radiation while 98% by SPF 30.

It means that a sunscreen with SPF of 15 will take 15 times more time to develop redness than without it. It means that a sunscreen with SPF 15 will take 15 times more time to develop redness than without it or in other words with SPF 15 you can stay 150 minutes without burning (15 x 10 minutes) in sun if you normally burn in 10 minutes. This means that higher the SPF, better the protection from the sun.

Sun Cream & Sunscreen Tips

The following tips are useful to know how to wear sunscreen.

  1. As the UV rays are strongest between 10 a.m. and 4 p.m., avoid going out during this time. The sun's rays are stronger at closer to the tropics i.e. higher altitudes and lower latitudes.
  2. Sunscreen or sun cream should be applied 20-30 minutes before you go out in the sun. It needs the opportunity to penetrate your skin to protect it.
  3. Choose a sunscreen that blocks both UVB and UVA and has a sun protection factor (SPF) of at least 15, SPF 30 (better) and SPF 70 for the face. Wear tightly woven clothes, sun glasses and a broad hat.

    Slip, Slap, Slop

    In Australia, the slogan to reduce the effects of sun damage is "Slip, slap, slop".
    Slip on a tee-shirt
    slap on a hat and
    slop on some sun cream.
  4. Apply very liberally to all areas of your body that are exposed.
  5. You should also apply sunscreen mixed with water on lips and hair before going out in sun, otherwise your lips will become chapped and dry and hair brittle.
  6. Re-apply your sunscreen every 2 hours, and even more often if you are swimming or camping. Reapply frequently even if it says water resistant or all-day protection.
  7. You should apply sunscreen even on cloudy days. The UV rays are not blocked by clouds. Note that snow, water and ice all reflect the sun's harmful UV (ultra violet) rays. The reflection of sun's ultraviolet rays from water, pools, oceans, lakes, snow, sand or buildings can intensify the effect. Sunlight can also penetrate water up to several metres deep, so take care while swimming.

    Myth about Sun screen: Sun screen is not required on a cloudy day or during winters.
    Fact : UV rays are even stronger on cloudy days and they penetrate through the clouds. That is why we get a tan even while sitting in a car. Therefore, you should apply sun screen even on a cloudy day or during winters.

  8. Discard the sunscreens that have expired. Over the time, the effectiveness of sunscreen diminishes.
  9. Wash sunscreens/cream at the end of the day.
  10. Sunscreen for Children

    Do not take out your child between 10am and 4pm as the sun is most intense during this time. Zinc oxide is the only FDA approved sunscreen for use on children under 6 months of age. However, as do not use sunscreens with nanoparticles as these are absorbed by the skin.
  11. Natural Sunscreen Recipe

How to Choose a Sunscreen?

  1. Always buy a broad-spectrum sunscreen that protects against both the UVA and UVB rays. Ensure that it does not contain para-aminobenzoic acid (PABA) if you are sensitive to it. Note that more expensive does not mean better.
  2. Buy a sunscreen with SPF of at least 15, preferably more.
  3. Choose a waterproof brand if you will be sweating or swimming.
  4. Try a sunscreen with different chemicals if your skin reacts badly to the one brand.
  5. Use a water-based sunscreen if you have oily skin or acne.
  6. Note the expiration date and discard that has expired.




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