What should I know about UVA and UVB rays?
Ultraviolet (UV) radiation rays are responsible for sunburn, skin cancer, and accelerated aging of the skin, also known as photoaging.
Approximately 95% of UV radiation is comprised of UVA type rays. UVA radiation is strong all day and all year long. Unlike UVA type rays, UVB type rays cannot go as deeply into the skin. and they are 400 times more intense in the summer and during mid-day hours (10 a.m. to 4 p.m.). UVB rays make up the other 5% of UV radiation.
UVB rays play a significant role in causing sunburn and skin cancer. UVA rays have more recently been linked to skin cancer and photoaging.
Who is at risk for skin cancer?
One in five Americans will develop skin cancer in their lifetimes, with the non-melanoma skin cancer types, which are basal cell and squamous cell carcinoma, being most common.
To estimate how specific skin types respond to UV light, our Stanford Skin Cancer Program uses the Fitzpatrick skin phototype scale, a scale that classifies a specific skin color and it’s response to UV light. People with fair skin (skin types 1 and 2 on the Fitzpatrick skin phototype scale) and those with increased numbers of moles, sun sensitivity or family history are more likely to develop melanoma.
Older men have the highest incidence and mortality rates from melanoma, but doctors are seeing a rise in new cases with young women. This is likely related to tanning bed use.
Melanoma is the deadliest form of skin cancer, accounting for only 4% of cases but over 80% of skin cancer deaths.
What type of sunscreen should I look for?
New FDA regulations require the relabeling of sunscreen products to filter out the entire range of UVB and UVA wavelengths to be labeled as “broad spectrum.” Effective UVB filters have been available for many years and are measured by the sun protection factor (SPF). Full UVA filtration has been harder to achieve. In the U.S., sunscreens that contain a photo stabilizing chemical called avobenzone provide the best UVA protection. Other UVA filters may be more effective but are not yet available in the U.S.
What is the biggest mistake people make with sunscreen?
The most common mistake is insufficient application. People often use only about one-fourth to half of the sunscreen they need to achieve the SPF level that is contained in the product. To protect your skin, it may be more useful to apply a higher SPF-containing sunscreen (30 or above) or simply increase the amount you are putting on your skin.
After finding and regularly using a brand that you like, a good rule is to use about 2 to 3 tablespoons for your body and 1 tablespoon for your face. Then, reapply every 2-4 hours.
It is also important to remember that waterproof sunscreens do not exist.
Depending on how well sunscreen maintains its SPF level after water immersion, sunscreens will soon be rated as either water resistant or very water resistant.
You can apply sunscreen just before you go outside, but you don’t want to put it on and jump right in the pool.
What about Vitamin D exposure?
Some companies in the tanning industry suggest that seeking a tan with artificial or natural UV light is good for vitamin D, but incidental sunlight likely provides enough vitamin D in most fair-complexioned individuals. If you need to increase your blood levels of vitamin D3, vitamin D3 supplementation is safer than exposing yourself to excessive UV radiation, like tanning beds. Follow the Institute of Medicine guidelines for how much vitamin D to take. We recommend a dose of 1,000-2,000 IU daily.
How do you convince people that sunscreen is worth the effort?
Research from 2010 shows that daily use of sunscreen reduces the risk of melanoma by 50% compared with optional use of sunscreen.
The benefits of sunscreen and sun protection in general (including avoidance of mid-day sun and tanning practices, and wearing hats, protective clothing and sunglasses) are well established in terms of reducing the photoaging process and preventing skin cancer.
Published April 2018
Stanford Health Care © 2018