Table of Contents
Sun Protection – Introduction
Though the body requires a certain amount of sun exposure to produce certain vitamins (such as vitamin D) and help eliminate chemical wastes from the body, ultraviolet 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.
Sun 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 ultravioletprotection 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, broadbrimmed 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.
Sunscreens that chemically block ultraviolet light from penetrating the skin’s surface became available 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 permits 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 recommend applying more sunscreen about every two hours during exposure (as well as SPF lip balms to protect the lips). Dermatologists recommend sunscreens that block both UVA and UVB lightwaves.
Because both sunscreen use and skin cancer are on the rise, some researchers have questioned whether sunscreens cause, rather than prevent, skin cancer. Though there are few clinical studies of such a correlation, so far there is no evidence to support this concern. Nor is there evidence to support claims that sunscreens promote estrogenic activity in the body, another concern that some people have raised. Health experts agree that proper application of sunscreen is the most effective defense to protect the skin from damage.
Time of Exposure
The sun’s ultraviolet light is most intense from 10 a.m. to 2 p.m. in the United States. Health experts recommend staying out of the sun as much as possible during that period of time, especially during summer months. When this is not practical, dermatologists recommend combining protective clothing and sunscreen for maximum protection.
See also CANCER RISK FACTORS.