Sun Safety: How to Beat the Burn this Holiday

CROATIA | Monday, 31 August 2009 | Views [653]

Sunburns

The main cause of sunburns is not the sun itself but the ultraviolet energy.  Just to complicate matters, there are three main types of ultraviolet (UV) energy, designated A, B and C.  Erythema is what your skin gets after a day in the sun, which is redness, some slight swelling and pain.  Doses of UV energy and its effect on the skin are measured in units called minimal erythema doses (MED).  This MED represents the smallest does of UV energy to cause that “sunburn” appearance. 

Beachgoers are typically exposed to 15 MEDs of UVB and 4-5 MEDs of UVA.  Almost all of UVC is absorbed by the Earth’s atmosphere.  There is increasing evidence that shows both UVA and UVB can be harmful to human skin and both can cause skin cancers. 

UVA rays penetrate the skin more deeply and are largely the cause of aged skin and wrinkles.  UVB is generally responsible for most “sunburn” effects and has traditionally been thought of as the cause of most skin cancers.  Ideally, persons in the sun should be protecting themselves with a sunscreen that blocks both UVA and UVB.

Sunscreens

Sun protection factor (SPF) is the ability of a sunscreen to protect skin from ultraviolet induced erythemas (sunburn).  This SPF number is calculated based on the length of time it takes to cause one MED in protected versus non-protected skin.  Basically, SPF is the amount of time it takes to causes a sunburn in someone with sunscreen protection versus someone who is unprotected.  At present, most sunscreens protect largely against UVB only, although there are some products that are beginning to protect against both UVA and UVB.  

SPF:                 % UVB absorption

2                                  50.0

4                                  75.0

8                                  87.5

15                                93.3

30                                96.7

50                                98.0

Chart from “A field guide to wilderness medicine” by Paul Auerbach, pg. 69

Clearly, one can see that UVB protection increases with the higher SPF and use of SPF 30 is becoming more and more advised.

How to Apply Sunscreen

• Apply liberally to all areas of exposed skin including backs of hands,  ears, nose and tops of feet

• Apply 15-30 minutes before swimming or water exposure

• Reapply immediately after exiting the water

• Using sunscreen and DEET based insect repellent will reduce the effectiveness of sunscreen by approx. 35%

What is in the sunscreen?

The ideal sunscreen spread onto your skin easy, does not cause allergy, pimples and does not stain clothing.  PABA (para-aminobenzoic acid) is the most common cause of sunscreen dermatitis and effects 4% of people.  Creams and lotions spread on the skin well.  Oils spread very easily but may cause pimples.  For extreme conditions a wax or ointment will help resist skin chapping.  Aerosols are often wasteful and leave parts of the skin over coated and others under protected due to difficulty in ensuring even spray. 

Sun protective clothing

Clothing that has been tested and proven to block the UV energy is designated by the term Ultraviolet protection factor (UPF) which is identical to SPF for sunscreen. 

The tightness of the fabric’s weave is most important in determining how effective it will be in blocking UV energy.  A good example of this is Lycra which can block nearly 100% of UVR when relaxed but only 2% when stretched tight.  A typical white cotton tshirt has a UPF of about 5-9. 

Wide brimmed hats are especially good for protecting the face, head and ears.  Sunglasses should be labeled to protect against UV energy and side shields do work in decreasing the amount of UV absorbed by the eyes.

Treating a Sunburn

Sunburns are largely self-limiting and will typically resolve on their own.  Treatment is largely centered on relieving symptoms.  Skin moisturizers and cool compress or cool water baths may help decrease the pain.  There is little evidence to suggest tradition treatments such as baking soda, aloe and oatmeal are effective pain relief but there is also a lack of decent studies.  Oral pain control can be achieved with either aspirin, acetaminophen or ibuprofen.  After a day in the sun, dehydration is also a factor and adequate water intake should also be assured. 

Watch out for those rays!

Tags: safety hub, croatia, sun safety, sunburn, sun protection, uv rays, health, travel

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