Friday, March 3, 2017

Do Sunscreens Really Prevent Sunburn?

Yes, they really do, BUT....this depends on what's in your sunscreen and how you are using it.

Sunburn is often the result of incorrect use of sunscreen, insufficient understanding of Sunscreen SPF, and insufficient understanding of UV Radiation exposure.

Here are some very important basic points to remember & pass on:

1. Sun damage to the skin occurs regardless of whether you experience symptoms of sunburn or not.  The effects of sun damage (skin cancer, aging etc) is insidious as it's often asymptomatic and accumulates over your life-time.

2.  The best sun protection is a physical barrier (hat, long sleeve shirt, sunglasses etc).  Please note that not all clothing provide the same degree of SPF.  For example, darker colours and tighter weave will confer more protection compared to lighter colours and light/open weave fabrics.  To ensure maximum SPF protection, opt for SPF rated clothing, as these are manufactured with an SPF additive (although this effect may be reduced with with time/laundering).

3. You can still receive substantial UV radiation exposure even when shaded from direct sun, due to the scattering & reflection of UV from the environments eg atmosphere, light coloured concrete/buildings/clothing, sand, water and snow.   Cloudy/overcast conditions minimally reduce UV radiation exposure, while reflection from water, sand & grass (& snow) increase UV radiation exposure by reflecting up to 70% of sunlight.

4.  Babies & Toddlers should always be covered with appropriate hat and SPF clothing as their skin is very sensitive and will burn easily.  Babies less than 12months of age should avoid direct sun exposure, and babies under 6mths should avoid using sunscreen due to their highly absorptive skin.

5. SPF is a UV filter and not a UV block.  Unfortunately, sunscreens are often incorrectly referred to as 'Sun Block'.  SPF relates solely to UV-B protection, and not UV-A.
UV-A = relates to increasing risk of skin cancer & responsible for age-related skin damage.
UV-B = relates to Sunburn & Skin Cancer

6. Always choose Broad Spectrum Sunscreens to protect against both UV-A & UV-B. (titanium/zinc oxide will offer some UV-A protection)   A physical blocker (hat, shirt, shade etc) is always best.  Sunscreen should only be one part of a comprehensive sun protection regimen (see point 1.)

7. SPF rating of 30-50 is best.  Anything lower than 30 offers inadequate protection, while anything higher than 50 is only very marginally more protective, & gives the wearer a false sense of security (this is why SPF is capped at 50+ in Australia)

8. Your maximum SPF = your burn time without sunscreen X the sunscreen's SPF.  So if you normally burn in 10min, a sunscreen with SPF50+ will give you 10x50 = 500mins of protection.
*Please Note: In reality, your SPF time is much less than this (approx only 30%) due to  factors like inadequate sunscreen application, sweating/swimming/clothing/touch reducing amount of sunscreen on the skin.  This is very important to factor in, to prevent sunburn.

9. On average, you require approx a shot glass of sunscreen to cover your whole body optimally (this is roughly the amount of sunscreen thickness necessary to achieve the SPF level stated on the sunscreen). And reapplication is essential every 2hours.

10. Reapplication of sunscreen does NOT increase your burn time nor reduce your dose of sunburn.  Once you reach your burn time, you must avoid the sun & get away from UV light.  No amount of sunscreen will stop you from burning once you exceed burn time, so always apply before sun-exposure & before burn time begins.

11. Your dose of sunburn can take hours to appear, so burn time is exceeded well before the effects can be seen.   This is a common misconception - people assume they are only starting to burn when they can the skin turn pink/red or peel.

11. All sunscreens should be applied at least 20-30min before sun exposure to allow it to the product to bond and set on the skin properly. for optimal protection.

13. All skin types burn - some just have a higher baseline protection factor.

I hope this has been helpful :)

Uyen Dinh
Consultant Pharmacist