Glossary

Basal Cell Carcinoma
The most common form of skin cancer, basal cell carcinoma usually appears as slow-growing, translucent, raised, pearly nodules which, if untreated, may crust, ulcerate, and sometimes bleed. If detected and treated early, there is a greater than 95 percent cure rate.

Broad-spectrum Protection
This refers to sunscreen products that contain ingredients to protect against both UVB and UVA rays.

Melanoma
The most dangerous of all skin cancers, melanoma is characterized by the uncontrolled growth of pigment-producing tanning cells (melanocytes). If detected in the early stages, melanoma can often be treated successfully, but in the later stages, it can spread to other organs and result in death.

Sunburn
The most common adverse reaction to the sun is the ordinary sunburn - also known as erythema. Burns from the sun are induced primarily by UVB radiation. The injury they cause is characterized by delayed redness and swelling followed by tanning and peeling. Sometimes the skin darkens without first reddening, but that does not mean that damage has not occurred. Chronic sun damage and sunburns especially in the first 18 years of life can result in dry, wrinkled skin and possibly skin cancer in later life.

Sun Protection Factor (SPF)
The Sun Protection Factor (SPF) is a ratio between the ultraviolet dose required to produce minimal erythema reaction (redness) in protected skin (skin with sunscreen) compared to unprotected skin (skin without any sunscreen). The number indicates how many times longer a person can stay in the sun before beginning to burn while wearing sun protection than if he or she were not wearing any sunscreen at all. This amount of time varies from one individual to another. SPF numbers usually range from 2 to 50.

Most dermatologists recommend that people use a sunscreen with an SPF of 15 or higher (for children under six, SPF 30 is recommended). It should be applied evenly and liberally before exposure to the sun and reapplied often. Reapplication is necessary more frequently if the user swims, engages in sustained vigorous activity, perspires heavily, or towels off.

Ultraviolet Radiation: UVA, UVB, UVC
Ultraviolet (UV) radiation is part of the sun's spectrum - wavelengths shorter than visible light. Ultraviolet rays are divided into UVA (320400 nanometers), UVB (290320 nm) and UVC (<290 nm). The UVA spectrum is further divided into UVA II (320340 nm) and UVA I (340400).

UVB rays are more intense in summer months, at higher altitudes, and in areas closer to the equator; UVB rays are the primary cause of sunburning, premature aging of the skin, and the development of skin cancer. UVA rays are more constant, year-round, and penetrate deeper into the skin's layers; UVA rays are also harmful and contribute to burning, premature aging of the skin and the development of certain forms of skin cancer. UVC rays are blocked by the ozone layer and do not reach the earth's surface.

Tanning beds primarily emit UVA rays. This kind of exposure does not show immediate signs of damage but over time, breaks down the skin's collagen and elastic and thereby can accelerate wrinkles, leathery skin, and skin cancers.

UV index
An estimate of the peak amount of ultraviolet rays reaching the earth's surface at noon.