UV Radiation & Your Skin

UV radiation is part of the natural energy produced by the sun. On the electromagnetic spectrum, UV light has shorter wavelengths than visible light, so your eyes can’t see UV, but your skin can feel it. Tanning beds also emit UV radiation. UV radiation is a proven human carcinogen.

Two types of UV light are proven to contribute to the risk for skin cancer:

• Ultraviolet A (UVA) has a longer wavelength. It is mainly associated with tanning and skin aging but can also lead to sunburn.
• Ultraviolet B (UVB) has a shorter wavelength. It is mainly associated with sunburn, but also causes a delayed tanning response and contributes to skin aging

UVA and UVB rays make a dangerous team. A sunscreen’s SPF number reflects both the amount of UVB and UVA protection it provides. It’s important to look for the words broad spectrum on a sunscreen product label, which means it has ingredients that can protect you from UVA as well as UVB rays. It’s crucial to protect your skin from both.

Bottom line: While UVA and UVB rays differ in how they affect the skin, they both do harm. Unprotected exposure to UVA and UVB damages the DNA in skin cells, producing mutations that can lead to skin cancer and premature aging. UV rays can also cause eye damage, including cataracts and eyelid skin cancers.

UV radiation is a proven human carcinogen, causing basal cell carcinoma (BCC) and squamous cell carcinoma (SCC).  These types of cancers often appear on sun-exposed areas of skin. Fortunately, when discovered and treated early, these common skin cancers are usually curable.

UV exposure that leads to sunburn has proven to play a strong role in developing melanoma, a dangerous type of skin cancer. Research shows that the UV rays that damage skin can also alter a gene that suppresses tumors, raising the risk of sun-damaged skin cells developing into skin cancer.

• A majority of nonmelanoma skin cancers (NMSC) and a large percentage of melanomas are associated with exposure to UV radiation from the sun.
• UV exposure is a powerful attack on the skin, creating damage that can range from premature wrinkles to dangerous skin cancer.
• Damage from UV exposure is cumulative and increases your skin cancer risk over time. While your body can repair some of the DNA damage in skin cells, it can’t repair all of it. The unrepaired damage builds up over time and triggers mutations that cause skin cells to multiply rapidly. That can lead to malignant tumors.
• The degree of damage depends on the intensity of UV rays and the length of time your skin has been exposed without protection. Location is also a factor. The UV Index measures the intensity of UV radiation at a specific location. If you live where the sun is strong year-round, your exposure level and risk increases.
• You can easily reduce your likelihood of developing skin cancer by protecting yourself against UV radiation.

• UVB penetrates and damages the outermost layers of your skin. Overexposure causes sunburn, tanning, skin aging and in severe sunburn cases, blistering.
• UVB plays a key role in developing skin cancer.
• UVB intensity fluctuates. While the sun’s rays are strongest and pose the highest risk late-morning to mid-afternoon from spring to fall in temperate climates and even greater timespans in tropical climates, UVB rays can damage your skin year-round, especially at high altitudes or on reflective surfaces like snow or ice.
• UVB rays can be filtered and do not penetrate glass.

• UVA rays cause skin damage that leads tanning, as well as skin aging and wrinkles. The slightly longer UVA rays travel deeper into the skin layers to cause damage. The shorter wavelengths of UVA also contribute to sunburn.
• UVA rays are proven to contribute to the development of skin cancer.
• UVA rays, while slightly less intense than UVB, penetrate your skin more deeply. Exposure causes genetic damage to cells on the innermost part of your top layer of skin, where most skin cancers occur. The skin tries to prevent further damage by darkening or tanning. There is no such thing as a safe or healthy tan; a tan is a sign of sun damage. Over time, UVA also leads to premature aging and skin cancer.
• UVA radiation is the main type of light used in most tanning beds. Once thought to be safe, we now know it is just the opposite.
• UVA is everywhere. UVA accounts for up to 95 percent of the UV radiation reaching the earth. These rays maintain the same level of strength during daylight hours throughout the year. This means that during a lifetime, we are all exposed to a high level of UVA rays.
• UVA can penetrate windows and cloud cover.

The UV Index measures the intensity of ultraviolet (UV) radiation from the sun at a location. It’s calculated using the latitude and altitude of that place, time of day, time of year, ground conditions, cloud cover and state of the ozone layer in the atmosphere. The UV Index is reported as a whole number between 0 and 11(+), with 0 indicating absolutely no sunlight (used only at night!) and 11 indicating extreme radiation, when you can burn in less than 10 minutes.

Daily Max UV Index

New York, NY

UV Index

0 (Low)

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You Need Sun Protection Every Day.
The Daily Max UV Index is non-medical opinion and is for illustrative, discussion, and entertainment purposes only and should not be used for preventing, diagnosing, or treating a medical or health condition.

Despite the risk factors, you can safely, happily enjoy the great outdoors by protecting your skin against UV exposure with broad-spectrum sunscreen and sun-safe clothing, hats and eyewear. You can also consider UV window film for your home and car.

Make it a way of life. Protect yourself every day, even when it’s cloudy. Avoid indoor tanning entirely. Get more details here: Your Daily Sun Protection Guide.

Reviewed by:
Anna Chien, MD
Heidi Jacobe, MD