Sunburn

How come some people get sunburn and others don't?
A lot depends on the person's pigmentation (skin type) - (pale, dark, or in between), and their exposure to the sun - time of day, season, altitude, latitude, snow, water, sand, how long they're exposed, and what they do to protect themselves.

Sun Radiation Type
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 fat. 
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.
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 by 10%.  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. 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.

How do you protect yourself?
First, avoid intense sun exposure if possible and watch out for sand, water and snow which reflect UV light back to you. Wear long sleeves and a wide brimmed hat and put on sunglasses and sunscreen. But which sunglasses and sunscreen?

Which sunglasses and why?
You don't need the real expensive kind. Just make sure the ones you get are polarized (to cut the glare), and protect against UVA and UVB radiation. Oh, and don't forget those things that keeps them on your head so you don't lose them.

What are sunscreens and how do they work?
Sunscreens are chemical or physical barriers to UV radiation. Chemical sunscreens are the lotions you apply to your skin that absorb the uv radiation. Some contain PABA (para-aminobenzoic acid) that absorb the UVB rays. Some have benzophenone that absorb both the UVB and UVA rays. The effectiveness of these chemical sunscreens depends on what's actually in it and its ability to withstand swimming and sweating. (You need to read the labels). Sunscreens have SPF (sun protection factor) ratings, too, which indicate how much sunburn protection they have relative to unprotected skin. The higher the number, the more protection, up to a certain point (which differs among the experts). You must apply the sunscreen (fairly liberally, approx 2mm thick) for it to work. It's better to put it on 30-60 minutes before going out in the sun, so it can penetrate and bind to the skin.

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:
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 person.

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:
Antihistamines, Oral contraceptives, Estrogen, Anti-inflammatories, Ibuprofen, Phenothiazines, 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.

The skin types outlined here are general descriptions and apply to the AVERAGE of each skin type. Other combinations of hair, eye and skin coloration can occur in each skin type. Individuals should exercise caution in determining skin type and the assistance of a dermatologist can be helpful.

There are six skin types categorized by scientists, depicted in the chart below. Skin type 1 burns most easily and skin type 6 rarely burns. In most cases, individuals think they are one skin type darker than they actually are. If your experience in sun exposure has been moderate, this is easy to do! If you determine that you fall between two skin types described, it is always safer to choose the lower value skin type.

SUNBURN RELIEF CHART

So what if you do get sunburn?
A Mild Sunburn, where the skin is pinkish-red, hurts and is warm to the touch. It is usually self limiting, lasting one to three days. Your doctor may recommend certain treatments, such as cool compresses, over the counter topical steroids, or lotions to relieve symptoms if necessary.
A Severe Sunburn, where the skin is a deep red, can also have swelling and/or blistering of the skin. It is extremely painful and can be associated with nausea, fever, and chills. See your physician immediately, as severe cases may need hospitalization.

Other Useful tips
Take a cool bath -- not ice cold, but cool -- and don't use bath salts, oil or bubble bath.
Do not scrub your skin or shave your skin. Use a soft towel and pat your skin dry.
Use a sunburn remedy containing aloe vera.
Use a light moisturizer or a dusting of powder to ease chafing.
Stay out of the sun. If the sunburn is severe or you are blistering, feel faint or nauseous, see a doctor immediately
Other rashes may mimic sunburns, so consult your doctor if there are any questions or doubts.

Don't end up looking like this!