What is the UV Index?
UV Index & Sun Protection
Origins of the UV Index
What Determines UV Strength?
Latitude & Time of Year
Time of Day
Reflection off Water
Reflection off Snow
Clear Skies & Clouds
UV Exposure & Your Health
Immune System Suppression
UV Exposure & Your Health
UV radiation can affect all of us, regardless of skin colour, by damaging our skin, eyes, and immune system. Some damage is immediate, such as sunburn, snow blindness, and immune system suppression. Other damage builds up over time, like skin cancer and cataracts. Skin cancer is highly treatable if detected early on, but if left to grow and spread it can be fatal, with survival rates below 15%.
UV exposure can cause chemical reactions in the skin which can directly and indirectly damage protein and DNA, causing cells to die or function abnormally. Cells that have been severely damaged may die off and disassemble, if this happens in large quantities it may be visibly noticeable in the form of the skin peeling. This is typical behavior following a sunburn. While these dead cells are being removed, the body replaces them with new ones. If the body deems the damage severe enough, the immune system will respond by sending immunization cells to the area, resulting in an inflammation of the skin or eyes where UV has penetrated.
Cells that are damaged but cannot be repaired and do not die off continue to live and function abnormally, which forms the basis for skin cancer to develop. As these defective cells multiply, the cancer will grow and spread.
Damage from sun exposure is cumulative over one's lifetime. Cumulative exposure to the sun imparts damage to the epidermis (the outer layer of the skin) and the dermis (the deeper layer where the skin's framework exists). Damage to the dermal layer causes elastin fibers to thicken and become more numerous. The skin's elasticity is lessened resulting in wrinkles and dry, coarse skin, causing what is referred to as skin aging.
When exposed to UV radiation the body's defence system increases it's production of melanin. Melanin gives the skin a brown pigmentation, which offers some (but not much) protection against UV, resulting in the skin appearing tanned. The purpose of melanin is to absorb UV radiation and dissipate the energy as harmless heat thus blocking the UV from damaging skin tissue. Because it takes a few days from the initial uv exposure for increased melanin to be noticeable in the skin, a tan will tell you that damage from UV has already taken place.
UVA gives a quick tan that lasts for days by oxidizing melanin that was already present and triggers the release of the melanin from melanocytes.
UVB induces a tan that takes roughly two days to develop because it stimulates the body to produce more melanin.
Skin damage from the Sun is largely avoidable by protecting yourself from the Sun especially when the UV Index is high. Our UV Forecast will tell you UV Index levels throughout the day and what Sun protection measures are advised.
UV & Eye Damage
The Sun's rays can also damage your eyes which may lead to cataracts, snow blindness, and eye cancer. Cataracts form cloud like growths in the eye and obstruct vision. Although it is possible to have cataracts removed by undergoing surgery, some simple things can be done to help prevent them in the first place.
Wearing a good pair of UV protective sunglasses or goggles, and a wide brimmed hat, especially when the UV levels are high or you are around highly reflective surfaces such as snow or water, is an easy way to protect your eyes. Sunglasses that fit properly and 'wrap around' offer better protection as they stop more of the reflected uv from reaching your eyes. Likewise, the wider the brim on your hat, the better the chances of your eyes being shaded from direct UV.
When purchasing sunglasses always check their UV protection qualities, and that they fit you properly and block as much of the Sun's rays as possible.
UV & Immune System Suppression
UV radiation can reduce the effectiveness of the immune system by altering the activity and distribution of some of the cells responsible for triggering immune system responses. A suppressed immune system reduces the body's ability to fight infections and disease. Therefore, UV exposure may enhance the risk of infection with viral, bacterial, parasitic or fungal infections. The effects of UV on the immune system are independent of skin color.
Relatively low doses of UVB compromise the immunological defences of the skin, thereby limiting the skin's allergic response to local attacks. For example, UV exposure can precede the onset of recurrent eruptions of cold sores (Herpes).
With increased exposure to UVB there is the risk not only of reducing the skin's defences but the body's entire immunological response. Research suggests that a sunburn can alter the distribution and function of disease-fighting white blood cells for up to 24 hours.