Table of Contents
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- Sun emits ultraviolet light, also known as ultraviolet
radiation. There are three types of ultraviolet radiation,
UV-C, UV-B and UV-A.
- UV-C does not impact the skin, and is effectively screened
by the atmosphere. Even with depletion of ozone, UV-C does
not have any impact on humans.
- UV-A is very harmful and penetrates not only the skin,
but also the eyes. UV-A rays penetrate the skin the deepest.
- Approximately 90% of UV-B is absorbed by the epidermis,
and approximately half of UV-A reaches the dermis and subcutaneous
- UV-A rays are the primary offenders in sunburn.
- Sunburn accelerates the aging process, manifested by
wrinkles and a pebble stone appearance of skin, which develops
over time. It is also a culprit in the increased risk of
cataracts and skin cancer.
- As per Dr. Auerbach, UV-B is 1,000 times more responsible
for inducing redness of the skin than UV-A. UV-B has its
own timeline, as opposed to UV-A, and onset is usually 2-4
hours after exposure, peaking after 12-36 hours, and fading
over 3 days.
- Please note: For those vacationing at high altitudes
or climbing enthusiasts, it should be noted that for every
1,000 foot increase in altitude, the UV intensity increases
- UV-A radiation does go through glass. Therefore, driving
in your car does not afford you protection against sunburn.
There are many contributing factors in getting a sunburn,
which include time of exposure, skin type, and geographic
location. As per Dr. Marilynne McKay, below are some general
guidelines to consider:
- After 12 minutes of exposure, a perceptible sunburn
may be apparent.
- After 30 minutes, vivid sunburn will be present.
- After 60 minutes, painful sunburn is apparent.
- After 120 minutes, blistering sunburn.
Sun Protection Factor (SPF)
What is the SPF value on sunscreen? This is defined by a
ratio of energy that is required to produce minimal redness
of the skin penetrating the sunscreen, compared to the amount
of energy required to produce the same reaction with the absence
of sunscreen. This gives you some idea of how long you can
remain in the sun before burning. An example as provided by
Dr. McKay, if one would normally burn in 10 minutes without
sunscreen, applying a 15 SPF would provide you approximately
150 minutes in the sun before burning, approximately 15 times
the protection. A sunscreen of 15 SPF filters out about 90%
of UV rays. It should be noted that filtration or protection
of UV-A in sunscreen is only about 10% of the UV-B rating.
It should be noted that these studies are carried out in
a controlled environment, and factors such as altitude, skin
type, wind, reflection of snow, sweating or toweling off of
sunscreen are not taken into consideration.
Important facts most individuals don’t
know: Per Dr. Marilynne McKay:
- Sunscreen needs to be applied one half hour before exposure
for full skin absorption.
- Waterproof type sunscreen should be applied at least
once an hour before going out into the sun.
- Sweating, swimming, and exposure to rain decrease the
effect of SPF.
- The FDA recommends reapplying sunscreen every 40-80 minutes.
- One ounce of sunscreen lasts no more than 4 days per
- SPF number does not apply to UV-A. So an SPF of 25 or
an SPF of 30 with no UV-A screen will be less effective
than a product with SPF that contains UV-A screen.
- Insect repellents containing Deet will decrease a product’s
SPF by anywhere from 15-30%.
- Always protect your eyes with good quality sunglasses.
The risk of cataracts needs to be underscored.
- Certain medications increase one’s risk of sunburn
by increasing the photosensitivity of the skin. Caution
should be exercised if taking the following medications,
although the list is not complete:
- Oral contraceptives.
- Certain antibiotics, specifically the sulfonamides.
- Diabetes medication.
- Certain diuretics.
- Anti-malarial medication.
- Tetracyclines such as Doxycycline.
- Some tricyclic antidepressants.
- Some deodorants and soaps.
- Some herbal medication such as St. Johnswort can
increase the risk of sunburn.
Clothing protection is very important when protecting oneself
from sunburn. Baseball caps are the worst since they do not
protect the ears, and the best hats are those that have a
brim at least 3” or greater all the way around. This
is not the time to be vain—in the outdoors, wear what
A study performed by Robson and Diffey determined an SBF
for 6 different clothing fabrics. The single most important
factor in determining SPF is the tightness of the weave, more
important than the actual fabric type. Lycra nearly blocks
100% of all UV radiation, but only 2% when maximally stretched
out. The typical white cotton shirt has an SPF of 5-9.
Is it important to go the tanning salons, and does it help
prior to going on a trip into the outdoors? The vast majority
of research shows that tanning beds and tanning salons are
absolutely dangerous. Tanning beds clearly contribute to photo
again and carcinogens. On average, tanning beds are contaminated
with approximated 2-10% of UV-B, more than the average UV-B
content in natural sunlight. As per Dr. Auerbach, tanning
bed exposure of over 15-20 minutes induces in DNA damage and
fibroblasts of the skin. In a Swedish study of 400 patients
in 640 controls, people who use sun beds, sunlamps, and tanning
booths before the age of 30 had a 7-8% increased risk of melanoma.
THE LONG AND SHORT OF THE ABOVE: DO
NOT GO TO TANNING BOOTHS.
After sunburn has resulted, there is not much than can be
done except make the patient more comfortable. Analgesics
such as aspirin and Ibuprofen may help the inflammation. Topical
steroids are of absolutely no help. Aloe gels can be helpful
in relieving pain. Applying cool water is also very effective.
Healthcare Provider- Medical Treatment
Survive Outdoors recognizes that when
blistering occurs, there is much controversy in terms of removing
the blisters or not in the outdoors, when far from treatment.
It is advised to keep the blisters on. They will help keep
the area clean. However, once reaching medical providers,
this author has always debrided the blisters and applied Silvadene
with very good outcome. Tapered doses of Prednisone are also
effective in severe cases in decreasing inflammation. In severe
forms, narcotic analgesics help to reduce the pain.
1. Wilderness Medicine,
4th edition, Paul S. Auerbach.
2. Sunscreens and Sun blocks,
Marilynne McKay, M.D.