From time to time, almost everyone spends too much time in the sun. The resulting burn is the body’s natural reaction to the over exposure. As ozone depletion increases, ultraviolet (UV) radiation increases. Light from the sun is the primary source of UV radiation (UVR) and over exposure is much more common. Damage to skin cells happens in much shorter time frames and has lead to an alarming increase in occurrences of skin cancer.
The sun emits a multitude of wavelengths. The main source of damage, though, generally stems from 2 of the 3 types of UV radiation: UVA, UVB and UVC. Although there are no safe UV rays, both UVA and UVB have been thought to contribute to skin cancer. UVA exposure causes cells to age and is linked to long-term skin damage like wrinkles, reduced skin elasticity and age spots. UVB exposure causes direct damage to the DNA usually taking the form of sunburns. UVB rays are the main target for causing skin cancer. UVC exposure is not normally blamed for skin cancer.
The UV Index
The level of UV exposure is determined by a number of variables: the time of the year, the time of the day, the elevation and the amount of cloud coverage. The UV Index (UVI) was developed by the Environmental Protection Agency (EPA) and the National Weather Service to offer a measurement of the amount of UVR that will hit the earth’s surface. The index ranges from 1 to 11 with a higher number indicating higher UV radiation exposure.
Selecting a Safe Sunscreen
When choosing a sunscreen, products with a higher sun protection factor (SPF) will provide a greater amount of protection. SPF only indicates the level of protection from UVB radiation. “Broad-spectrum” products, that contain at least 3 active ingredients, provide protection from both UVA and UVB rays. Ingredients may include avobenzone, ecamsule, zinc oxide, or titanium dioxide.
Although sunscreen does not give total protection, the American Cancer Society (ACS) recommends sunscreens with an SPF of 15 or higher; and other organizations such as the American Academy of Dermatology recommend at least 30. SPF 15 filters out about 93% of UVB rays, SPF 30 about 97%, and SPF 50 about 98%.
Most sunscreens require reapplication every 2 hours or less for continual protection. Swimming, sweating and reapplication greatly affect protection. “Waterproof” products are designed for 80 minutes of sweating or swimming protection whereas “water resistant” products protect for 40 minutes. According the the ACS, when applied correctly with a thick coat, using SPF 30 is equivalent to 1 minute of unprotected UVB rays every 30 minutes. So, 1 hour with an SPF 30 application is equal to 2 minutes of unprotected time in the sun.
