The keratinocytes bear the brunt of the expo-
sure, and about 8 to 12 hours later show the con-
sequences. The damaged cells release toxins and
other substances that draw increased BLOODflow
to the dermis. The additional blood flow causes
the skin to become red (erythema). These toxins
irritate the nerve endings in the epidermis and
dermis, causing PAIN. Fluid may accumulate
between the cells (edema), causing swelling. With
more severe damage, fluid-filled blisters form on
the skin. Discomfort peaks about 48 hours after
exposure. At about this same time, the melano-
cytes have infused keratinocytes migrating from
the dermis to the epidermis with melanin, giving
them a darker pigment that will offer better pro-
tection than their predecessors had.
The most effective treatment for sunburn is a
combination of moisturizing lotion or gel such as
aloe vera to soothe the irritated skin and a nons-
teroidal anti-inflammatory drug (NSAID) such as
ibuprofen to relieve INFLAMMATIONand pain. Most
sunburn discomfort resolves in three to five days.
Badly sunburned skin that has blistered is likely to
peel at this point and requires gentle cleansing to
minimize the risk for bacterial INFECTIONuntil the
new skin completely heals. Researchers now
believe one significant sunburn is sufficient to lay
the groundwork for skin cancer decades later.
Repeated mild to moderate sunburns appear to
have similar effect. Sunscreens and protective
clothing worn during sun exposure can protect
against sunburn.
See alsoBLISTER; BURNS; KERATINOCYTE; MELANOCYTE;
NONSTEROIDAL ANTI-INFLAMMATORY DRUGS (NSAIDS);
SKIN CANCER; SKIN SELF-EXAMINATION; SUN PROTECTION.
sun protection Methods to safeguard the SKIN
from SUNBURNand sun damage. Though the body
requires a certain amount of sun exposure to pro-
duce certain vitamins (such as vitamin D) and help
eliminate chemical wastes from the body, ultravio-
let light is a potential hazard for the cells. Melanin
production, which results in darkening the skin, is
the body’s primary method for protecting itself. The
lighter a person’s natural skin color, however, the
less effective this method. Many health conditions
that affect the skin, most notably SKIN CANCER, result
from overexposure to the sun and in particular to
ultraviolet B (UVB) light.
Protective Clothing
Clothing that covers or shades the skin surfaces is
the most effective protection from sun exposure
and can block more than 90 percent of the sun’s
ultraviolet light, though it is still possible to
acquire a sunburn through clothing. Fabric with a
tight weave is more effective than fabric with a
loose weave. Many items currently manufactured
specifically for outdoor activities now use yarns
and weaving techniques that substantially block
ultraviolet light. Manufacturers use ultraviolet-
protection factor (UPF) ratings to designate the
extent of the fabric’s ability to prevent ultraviolet
light penetration. The higher the UPF rating, the
more effective the protection. Solid-weave, broad-
brimmed hats help protect the scalp and shelter
the ears, NOSE, and back of the neck. Technical
gear for many outdoor sports, such as bicycling
and kayaking, includes gloves that protect the
hands from friction and pressure as well as sun
exposure. Sunglasses that block UVA and UVB
light are necessary to shelter the eyes.A sunscreen product’s SPF rating
applies only to UVB blocking, so it is
important to read the product label to
determine what protection the product
can provide.Sunscreen
Sunscreens that chemically block ultraviolet light
from penetrating the skin’s surface became avail-
able in the 1980s. These chemicals work by
absorbing the light so it does not reach the cells.
Most sunscreens block UVB; some also block UVA.
A sunscreen’s sun-protection factor (SPF) rating,
provides a general idea of how long the product
can provide protection based on a time-related
formula. In general, a fair-skinned person will get
a sunburn after about 10 minutes of unprotected
exposure to the sun. A sunscreen’s SPF rating is a
multiplier of that marker. A sunscreen with an
SPF rating of 15, for example, theoretically per-
mits 15 times as long in the sun before burning, or
150 minutes. A sunscreen with an SPF of 30
would allow 300 minutes. These are general
guidelines, however, and dermatologists recom-
mend applying more sunscreen about every twosun protection 201