Sun Protection After Burns
Time For a Practical Approach
By David G. Greenhalgh, MD
Chief of Burns, Shriners Hospitals for Children Northern California and University of California, Davis
Some burn patients are advised to totally avoid the sun for a year or even for their lifetimes. Others are told that sun exposure is acceptable if they use some type of protection. Here are some facts about the changes your skin goes through after a burn injury and some guidance on protecting yourself from the harmful rays of the sun:
Why Skin Color Is Affected by a Burn
When you suffer a second-degree (or partial thickness) burn, you lose the outer most layer of skin, or epidermis. Because melanin, which gives skin the brown or black pigment that defines skin color,1,2 exists in the epidermis, that pigment has also been lost. As a result, second-degree or deeper burns that heal spontaneously are initially pink and unpigmented. The deeper the wound, the slower the re-pigmentation process. You may initially see brown dots at the hair follicles that enlarge and gradually coalesce to form new pigment. However, the entire re-pigmentation process may take more than a year to be completed and very deep wounds may, in fact, never regain pigment.
Unfortunately, we do not have much control over the extent of re-pigmentation. There is often a color difference in the healed burn wound and the surrounding area, and the deeper the burn, the more difficult it is to get a good color match. Controlling the extent of the final pigmentation is difficult—injured areas in some burn survivors wind up lighter (or hypo-pigmented) while others become darker (or hyper-pigmented) than the surrounding skin. You probably already know that sun exposure increases pigmentation, what we usually call “tanning.” However, during the period of re-pigmentation, sun exposure may also affect the final pigmentation outcome. That is why burn patients are advised to be careful in the sun—too much exposure may result in the injured area becoming darker than the areas surrounding it. (More on that later.)
The Process of Re-pigmentation
Currently, the main way to re-pigment areas that lack color is to create a new wound—usually with dermabrasion—and then place a new graft.3 Skin grafts carry pigments to the new site and, for an unknown reason, are often darker than the surrounding area. Hypo-pigmented areas can also be tattooed, but it is difficult to get a good color match and tattoos tend to fade with time. If dark skin develops at the site of your injury (hyperpigmentation), it can be lightened with hydroquinone creams; however, the extent and uniformity of lightening cannot be controlled when using these products. So it is important to keep in mind that the likelihood of hyperpigmentation (or darker skin in the area of your injury) can be reduced by limiting your sun exposure.
Understanding the Negative Effects of the Sun
Skin can be damaged by all wavelengths of light, from infrared to ultraviolet. However, ultraviolet light is the greatest cause for concern. It was once believed that darker pigmentation offered protection from light damage but darker skin is also damaged from ultraviolet light.
Of the three types of UV wavelengths, it is UVB that provides the greatest risk to skin. UVB light will produce erythema (redness), typically known as “sunburn” after 8-24 hours of exposure. UVB light also induces “tanning” by increasing the number of specialized cells called “melanocytes” and stimulating them to produce more melanin. This “delayed tanning” starts 2-3 days after exposure and peaks at 3 weeks, however, skin does not return to the original color until 8-10 months later. It also causes photochemical damage to DNA and is thus involved “photo-aging” (thinning, wrinkling, sagging, and other changes due to sun exposure). UVB light is also tied to the formation of skin cancers, although the relationship is not quite clear since it appears that it increases the chances of one type of skin cancer (squamous cell) and may not be as great a factor in inducing other types (basal cell and melanoma).
UVB light does have a beneficial effect—it stimulates vitamin D synthesis in the epidermis. However, only a small area needs to be exposed and only 5% of the light needed to produce redness is required for Vitamin D production.
UVA light leads to rapid tanning (within 2 hours) and has 1000-fold less erythema-inducing effects, compared to UVB light. However, UVA light does contribute to photo-aging and it is a likely contributor the development of skin cancers.
Taking Appropriate Precautions
Strategies that you can use for protecting yourself from these negative effects of the sun fall into three categories: environmental, physical, and chemical.
Environmental protection strategies follow these “common sense” suggestions4:
- People at risk (such as burn patients) should avoid direct exposure between noon and 3:00 pm when half of the daily solar UV dose reaches the ground (or as the American Academy of Dermatology recommends, between 10:00 am and 4:00 pm5).
- Keep in mind that elevation above sea level also influences the extent of UV exposure. For every 300 meters in elevation, there is a 4% increase in UV light exposure. For every degree of change in latitude, there is a 3% increase in UV exposure. So the highest risk is at high elevations near the equator.
- Fog, haze, or clouds can reduce UV exposure by 10-90% but, remember, sunburns can still occur.
- Snow, sand, and metal can reflect up to 90% of UV light, increasing your exposure.
- Sea water can reflect up to 15% of UV light, but pool water does not reflect much.
- UV light will penetrate approximately 1 meter into water so swimmers are at risk.
- Shade is an obvious environmental protector from sunlight, but you may be surprised to learn that a beach umbrella provides less protection from the sun than dense foliage.
Physical protection from the sun is usually achieved through photoprotective clothing. However, the protective effects of clothing vary greatly and no current standards exist in the United States for “sun
protective” clothing. A light-colored cotton shirt provides a sun protection factor (SPF) of only 10 and one third of summer clothing is reported to have had an ultraviolet protection factor (UPF), a measure of total UVA and UVB light blocked, of 12-154.
So keep in mind the following characteristics of clothing when choosing what to wear in the sun:
- Loose fitting, dry clothing with tightly woven, thicker, darker, and unbleached fabrics offer more protection. Denim, wool, and synthetic fabrics or those treated with an ultraviolet absorber are also safer.
- Loosely woven, lighter colored (bleached) and thinner fabrics have less protection from the sun. Cotton, linen, acetate, and rayon clothing provide less UV light protection.
Chemical protection is offered by topical sunscreens, which are divided into two forms:
- Inorganic sunscreens include zinc oxide and titanium dioxide. These agents both reflect and absorb UV and visible light. The inorganic sunscreens are very effective but they are less cosmetically acceptable since they are obviously white on the skin.
- Organic sunscreens absorb UV radiation and are divided into UVB absorbers, UVA absorbers, and broadband absorbers (absorbing UVA and UVB light). UVB absorbers have been available for many years but recent evidence suggests that UVA light is also involved in the development of skin cancers. Therefore, you can now buy sunscreens that absorb both UVA and UVB light.
The effectiveness of these products is measured by the sun protection factor, or SPF.
So what does this mean for patients recovering from a burn injury? I propose that burn patients follow the guidelines that all people should to protect themselves from photo-aging and skin cancers. In addition, burn patients should be extra cautious with exposing those burns that are regaining their pigment to improve the ultimate color match. Once pigment has stabilized, burn survivors should follow the recommendations designed for the general population.
The American Academy of Dermatology recommends the following to reduce UV light exposure5:
- Seek shade and avoid sun between 10:00 am and 4:00 pm.
- Wear protective clothing, including wide-brimmed hats.
- Beware of water, snow, and sand reflecting light.
- Avoid tanning beds.
- Use sunscreen, regardless of your skin color, as follows:
– Apply a water-resistant, broad-spectrum sunscreen (UVA and UVB protection) that is rated at SPF 30 or greater.
– To cover the exposed areas in an average adult, use 1 ounce (a shot glass) per application.
– Wait 15 minutes for the sunscreen to absorb in the skin before exposure.
– Reapply sunscreen every 2 hours or after swimming or excessive sweating.
Take Special Precautions for Children
In addition, the American Academy of Pediatrics recommends that all children younger than 6 months of age should be kept out the sun whenever possible.6 Children old than 6 months should follow the same recommendations as those mentioned above for adults. They also remind us that 80% of the lifetime sun exposure takes place before the age of 18 years of age.
Enjoying Some Time Outdoors
The goal for any recovering burn survivor is to regain as much function and activity as possible. Going outside is important for all people. Burn survivors should not avoid such activities but instead should use common sense when exposed to sun.
Again, burn survivors should be extra cautious when their wounds are regaining pigment. Otherwise, following the guidelines that apply to all people for sensible exposure to the sun is the best recommendation.
Explore our Resource Library for more resources on the physical, social, and emotional aspects of burn recovery.
- Lin JY, Fisher DE. Melanocyte biology and skin pigmentation. Nature. 2007;445:843-850.
- Costin G-E, Hearing VJ. Human skin pigmentation: melanocytes modulate skin color in response to stress. FASEB J. 2007;21:976-994.
- Grover R, Morgan BDG. Management of hypopigmentation following burn injury. Burns. 1996;22:627-630.
- Lautenschlauger S, Wulf HC, Pittelkow MR. Photoprotection. Lancet. 2007;370:528-537.
- American Academy of Dermatology. Understanding skin cancer. Available at: http://www.aad.org/dermatology-a-to-z/health-and-beauty/general-skin-care/sun-protection/how-do-i-prevent-skin-cancer. Accessed April 15, 2014.
- Quatrano NA, Dinulos JG. Current principles of sunscreen use in children. Curr Opin Pediatr 2013;25:122-129.