Tuesday, July 8, 2008

UV Safety Month: Understanding Ultraviolet Radiation

Traditionally, May has been the designated time when national promotional efforts are focused on skin cancer prevention. (Though, in reality, skin cancer prevention is a year-round issue). The subject of skin cancer prevention/sun safety has resurfaced this month - July has been officially named "UV Safety Month".

Speaking of UV safety, particularly in relation to skin cancer prevention, I'm reprising a Blog post I wrote last year that describes (in laymen's terms) how ultraviolet radiation works - it’s dangers, why we need to be aware of it, and how to protect ourselves:

Understanding Ultraviolet Radiation - Q&A

Q. What is solar ultraviolet radiation?

A. Ultraviolet radiation (UVR) is defined as the portion of the electromagnetic spectrum between 100 nanometers (nm) and 400nm. Ultraviolet radiation is classified by wavelength into three regions: UVA - Ultraviolet radiation in the range 315nm to 400nm is thought to contribute to premature aging and wrinkling of the skin and has recently been implicated as a cause of skin cancer. UVB - Ultraviolet radiation in the range 280nm to 315nm is more dangerous than UVA and has been implicated as the major cause of skin cancers, sunburns, and cataracts. UVC - Ultraviolet radiation in the range 100nm to 280nm is extremely dangerous but does not reach the earth’s surface due to absorption in the atmosphere by ozone.

Q. How are people exposed to UVR?

A. Solar UVR is the single most significant source of UVR and can reach a person on the ground from three sources, directly from the sun, scattered from the open sky and reflected from the environment. This means that even if a person is shaded from the direct sun they can still receive substantial UVR exposure from the open sky. Also some ground and building surfaces are quite reflective to UVR including white paint, concrete and metallic surfaces. These surfaces can reflect UVR onto the skin and eyes. Reflective surfaces can reduce the effect of protective measures. There are also many types of artificial UVR sources, some of which emit high levels of UVR. Arc welders used in industry produce an intense UVR emission and workers exposed to welding radiation may suffer similar health effects to workers with over exposure to solar UVR. There are many other forms of artificial UVR sources such as fluorescent lamps, mercury vapor, metal halide and quartz halogen lamps used in industry, offices and in the home.

Q. How is UVR measured?

A. Broadband UV biometers and pyranometers are generally used to measure or monitor solar UVR. These instruments measure global solar UVR received on a horizontal surface from the entire hemisphere of the sky. Solar radiation includes both UVR transmitted directly and scattered UVR from the atmosphere, so the design of these instruments ensures measurement of both direct and diffuse radiation. These instruments can also be used to monitor changes in ozone levels and cloud cover effects by measuring changes in UVR irradiation levels.

Q. What are the effects of exposure to UVR?

A. Major organs at risk from exposure to UVR include skin and eyes as the penetration depth of UVR is very short. Ultraviolet radiation can be produced by various artificial sources but for most people the sun is the predominant source of UVR exposure. For outdoor workers without adequate protection or control measures the levels of solar UVR may exceed the generally accepted exposure limits. Those who have been over-exposed to UVR may be unaware of their injury as UVR cannot be seen or felt and does not produce an immediate reaction. Over-exposure to UVR can cause sunburn, skin damage and skin cancer. The most obvious short-term effect of over-exposure to UVR is sunburn. The more UVR exposure, the worse the sunburn becomes. A person’s cumulative exposure to UVR along with the number of severe sunburns they have received, especially during childhood, increases their risk of developing skin cancer. Sun exposure causes the outer layers of the skin to thicken and long-term exposure can cause skin to wrinkle, sag and become leathery. Melanoma, the least common of the skin cancers but the most dangerous, may be related to severe exposure to solar UVR at an early age. Malignant melanomas may appear without warning as a dark mole or a dark “spot” on the skin. UVR exposure also places our eyes at risk of photokeratitis, photoconjunctivitus, ocular melanoma, and cataracts. Cataracts is one of the most common types of eye damage in Australia. Cataracts is the clouding of the lens of the eye, which is responsible for focusing light and producing sharp images. Without intervention, cataracts can lead to blindness.

Q. How can I reduce my risk from UVR exposure?

A. Increasing public awareness and interest in UV protection is due in part to the requirements for occupational protection of outdoor workers as well as the provision of UVR protection for the recreational market. Behavior outdoors can significantly affect a person’s solar UVR exposure and use of items of personal protection can provide a substantial reduction in the UVR dose received. Many forms of personal protection are available to reduce a person’s exposure to solar UVR. The best protection is to avoid peak hours of 10:00 AM and 4:00 AM when the sun's rays are most intense, coupled with proper sun protection year-round (even on cloudy and cold days). When outdoors, wear sun protecting clothing with good body coverage (rated at UPF 50+), a wide-brimmed hat, UV protective sunglasses and SPF 30 sunscreen. Over recent years interest has extended to shade structures and the UVR protection offered by commonly used materials such as shadecloth, plastic roofing materials, glass and window tinting films, even specially manufactured sun protective clothing. Additionally, everyone should avoid tanning beds. There is NO SUCH THING AS A SAFE TAN!

Q. What is the UV Index?

A. Some exposure to sunlight can be enjoyable; however, too much could be dangerous. Overexposure to ultraviolet (UV) radiation can cause immediate effects such as sunburn and long-term problems such as skin cancer and cataracts. The UV Index, which was developed by the National Weather Service and the U.S. Environmental Protection Agency (EPA), provides important information to help you plan your outdoor activities to prevent overexposure to the sun’s rays. The UV Index provides a daily forecast of the expected risk of overexposure to the sun. The Index predicts UV intensity levels on a scale of 1 to 11+, where low indicates a minimal risk of overexposure and 11+ means an extreme risk. Calculated on a next-day basis for every ZIP code across the United States, the UV Index takes into account clouds and other local conditions that affect the amount of UV radiation reaching the ground in different parts of the country.

UV Index Number Exposure Level
0 to 2 Low
3 to 5 Moderate
6 to 8 High
8 to 10 Very High
11+ Extreme

With 90-95% of skin cancers resulting from over-exposure to ultraviolet radiation from the sun and tanning, skin cancer is largely preventable. Yet, in order to prevent skin cancer we must take proactive measures to protect ourselves and youth from it. The media and society, as a whole, may not recognize the seriousness of skin cancer and how incidence is growing at epidemic rates; however, I will continue to do bring this issue to light in hopes to not only raise awareness but convince people to protect themselves. We have a responsibility to do what is necessary to protect ourselves and others from skin cancer, especially when we can largely PREVENT it. The first step is proper education about skin cancer prevention. And the first step in preventing skin cancer (or, at least, significantly reducing our risk) is protecting our skin from over-exposure to damaging, even carcinogenic (cancer-causing) ultraviolet radiation. In turn, one of the most effective methods of protecting our skin from UV exposure is proper year-round use of a quality SPF 30 sunscreen (see www.bluelizard.net) and UPF 50+ sun-safety clothing (see UVSkinz.com).

For more information about quality sunscreens and sun protective clothing, see previous Blog posts.

That being said, UVSkinz is extending its offer to give a FREE UV protective shirt (with every purchase) until August to celebrate UV Safety. Please see www.UVSkinz.com to learn more about how you can get a free UPF 50+ (SPF 30) sun-safety shirt for your family.

Sources: American Academy of Dermatology & ARPANZA.

Copyright. Danielle M. White, The Cancer Crusaders Organization 2005-2008.