Did you know the sun’s ultraviolet rays can damage your skin in as little as 15 minutes? Ultraviolet (UV) radiation can cause everything from premature aging of the skin to eye problems to cancer. According to the American Cancer Society, UV rays can even weaken the immune system, making it harder for the body to fight off infections. People who live in areas with year-round, bright sunlight, like San Diego County, have a higher risk of skin cancer than people living elsewhere.
Now that summer is in full swing, it is more important than ever to take precautions against harmful UV rays.
UV Radiation: An Overview
Radiation is the emission of energy from any source. UV radiation is a form of electromagnetic radiation. It is sent out, or radiated, from the sun or man-made objects, such as tanning beds. Types of radiation vary from high frequency, like gamma rays and X-rays, to low frequency, like radio waves. The higher the frequency, the shorter the wavelength, and the more damage the rays can do. UV rays are medium-frequency rays.
High-frequency UV rays have enough energy to remove an electron from an atom or molecule, therefore, damaging the DNA in cells, which can lead to cancer. Since UV rays do not have enough energy to penetrate deep into the body, the damage they do begins on the skin.
The three types of UV radiation are:
- UVA rays: UVA rays are the lowest-frequency UV rays and can cause indirect damage to cells’ DNA. UVA rays also do long-term damage to the skin, causing wrinkles and some skin cancers.
- UVB rays: UVB rays have a slightly higher frequency than UVA rays. They cause sunburns, can damage skin cells’ DNA, and are the most common cause of skin cancer.
- UVC rays: UVC are the highest frequency of the UV rays. They react with ozone high up in the atmosphere and do not reach humans, but they can also come from certain man-made sources, like welding torches, mercury lamps like those found in stadiums, and sanitizing wands.
UV Exposure from the Sun
The strength of UV rays from the sun is dependent on several factors, including:
- Time of day: Strongest UV rays reach the ground between 10 a.m. and 4 p.m.
- Season of the year: UV rays are strongest in the spring and summer months in North America.
- Distance to the equator: The closer to the equator, the greater the UV exposure.
- Altitude: The higher the elevation, the greater the UV exposure.
- Clouds: UV rays can still reach the ground on cloudy days, but clouds tend to block some UVB rays.
- Reflection from surfaces: Water, sand, snow, and pavement can cause UV rays to reflect onto people, leading to an increase in exposure.
- Air quality: Ozone, high in the upper atmosphere, can help filter some UV rays.
The strength of the rays on a given day, the amount of time spent in the sun, the complexion of a person’s skin, and whether that person is being protected from UV rays by clothing or sunscreen also factor into the amount of UV exposure one gets.
Most skin cancers result from exposure to sunlight, which emits UVA rays. The most common types of skin cancers are basal cell and squamous cell. They appear on parts of the body that are often exposed to the sun, and their occurrence is commonly related to lifetime sun exposure. Melanoma, the most serious form of skin cancer, can result from sun exposure as well, and man-made sources of UV rays can produce skin cancer, too.
Skin cancers include:
- Basil cell carcinoma (BCC): About 80 percent of the 3 million cases of skin cancer diagnosed annually are basal cell carcinoma. People with fair skin are most at risk. BCCs are commonly found on the head, neck, face, and arms but can appear anywhere on the body. Early diagnosis and treatment are important because the cells can grow deep, damaging the nerves and bones.
- Squamous cell carcinoma (SCC): The second most common form of skin cancer, SCC appears as firm red bumps, scaly patches, or sores that seem to heal and then reopen. Light-skinned people are most at risk, but darker-skinned people are not immune. SCC can grow deep in the skin and spread to other areas of the body.
- Melanoma: This is the most serious type of skin cancer, and it tends to spread. Melanoma can grow inside moles already on the skin or appear as dark spots that look different than typical dark spots. It is crucial to get melanomas diagnosed and treated because they can be deadly. People should be aware of the “ABCDEs” of melanoma. These warning signs include:
- Asymmetry—one half is different from the other half
- Border—an irregular-shaped border that looks ragged or notched
- Color—varying colors from one area to the next, some brown, black, pink, red, white, or blue
- Diameter—typically 6 millimeters, or the size of a pencil eraser, although often smaller when diagnosed
- Evolving—looks different from other skin spots, and changes in size, shape, and color occur
- Other less-common types of skin cancer include cutaneous T-cell lymphoma, dermatofibrosarcoma protuberans (DFSP), merkel cell carcinoma, and sebaceous carcinoma.
Ways to Stay Protected from UV Rays
There are ways people can protect themselves from UV rays. For one, before heading outside, check the U.S. Environmental Protection Agency’s UV Index to learn what the expected risk of overexposure to UV radiation from the sun is for any given day. Type in a ZIP code to get local results.
Other ways to stay protected include:
- Clothing: Wearing long-sleeved shirts and pants (darker colors are best) can provide protection; also look for clothing with an ultraviolet protection factor.
- Hats: Wide-brimmed hats, with a brim of about two to three inches that shields the face, ears, and neck, are best.
- Shade: Shade from trees, shelters, and umbrellas offer protection from direct sunlight and UV rays.
- Sunglasses: Sunglasses protect eyes from UV rays, reducing the risk of cataracts, macular degeneration, and growths on the cornea. They also protect the delicate skin around the eyes. For the best protection, choose wraparound lenses and sunglasses that block both UVA and UVB rays. Sunglasses that are labeled as “UV400” or “meets ANSI UV requirements” block nearly 100 percent of UV rays. Fortunately, most inexpensive glasses protect as well as pricey ones. People who spend time in the sand, snow, or water, may want polarized lenses, which cut down glare from other surfaces.
- Sunscreen: Sunscreen can help filter UV rays but not totally block them. The American Cancer Society recommends sunscreen but warns against relying on it to prolong one’s exposure to the sun.
What Is SPF?
Sun protection factor (SPF) is used to measure a sunscreen’s ability to protect from the UVB rays that cause sunburn. SPF ratings that protect against both UVA and UVB rays range from a low of 15 to a high of 100. The higher the SPF, the more UVB protection a product affords, although the benefits become negligible when going over a 30 rating. Anything lower than a 15 should not be used.
An SPF of 30 provides the wearer with the equivalent of one minute of UVB rays for each 30 minutes spent in the sun. So, for example, someone spending an hour in the sun using a sunscreen with an SPF of 30 will get the same exposure as if they were completely unprotected for two minutes. Unfortunately, most people get less protection because they do not apply sunscreen often enough or cover their entire exposed bodies.
The value of sunscreen depends on its SPF number:
- SPF 15 sunscreens filter out about 93 percent of UVB rays
- SPF 30 sunscreens filter out about 97 percent of UVB rays
- SPF 50 sunscreens filter out about 98 percent of UVB rays
- SPF 100 sunscreens filter out about 99 percent of UVB rays
Types of sunscreen:
- Broad spectrum: Broad spectrum sunscreens have been shown to protect against both UVA and UVB rays. Ingredients to look for are avobenzone, zinc oxide, and titanium dioxide.
- Water resistant: Sunscreens labeled “water resistant” can protect the skin even when it gets wet. The U.S. Food and Drug Administration (FDA) requires manufacturers to state whether their product protects for 40 or 80 minutes of swimming, playing watersports, and sweating.
Good sunscreen should last two to three years. Check the expiration date to be sure it is still effective. Shake the bottle to remix the ingredients if they have settled. Keep sunscreen in a cool, dark place when possible.
To maintain protection, reapply sunscreen every two hours—or more often if the wearer is in the water or sweating.
Other UV Safety Concerns
- Children: Children tend to spend more time outdoors and can burn more easily than adults. Parents should be sure their children are wearing hats and protective clothing, staying in the shade, and applying sunscreen. Babies under six months old always should be protected by hats and never be out in the direct sunlight. Sunscreen is OK to use on a baby’s unprotected skin (look for sunscreen made for babies and children) if those areas cannot be covered by clothing or shade.
- Tanning beds: Although some may believe the UV rays in tanning beds are harmless, the truth is that tanning beds give off UVA and UVB rays, contributing to skin damage and cancer, including melanoma, especially if first exposure is before age 30. Try sunless tanning lotions to provide a darker skin color.
- UV lamps: UV lamps used in nail salons can also give off UVA rays, although at a much lower amount than tanning beds. Sunscreen applied to the hands can help prevent UVA-ray exposure when using a lamp.
- Chemicals in sunscreen: Concerns have arisen in the past few years over the link between chemicals in sunscreen and cancer. In 2019, the FDA deemed two ingredients—aminobenzoic acid, or PABA, and trolamine salicylate—unsafe. Do not use products with these ingredients. Oxybenzone is another of the common ingredients in sunscreen that has raised concern. The FDA currently considers it safe, but some environmental groups and health organizations claim it is potentially harmful to the environment, especially coral reef habitats, as well as to some people who may be allergic to it. Laboratory tests have also shown it to interfere with a body’s hormones. Although no definitive evidence has come forth on oxybenzone, two ingredients the FDA does propose are safe and effective are titanium dioxide and zinc oxide.
- Sun exposure and vitamin D: The sun can provide vitamin D, but scientists are unsure just how much sun exposure is safe to offer a benefit. Since the risks from sun exposure are great, taking vitamin D supplements is the safer way to acquire the vitamin.
- Heatstroke and heat exhaustion: Too much sun exposure, especially when combined with activity, can cause the body to overheat. Heat exhaustion and heatstroke may result. Heat exhaustion requires first aid, including moving the person into the shade, removing heavy clothing, and administering cool water while monitoring. Heatstroke, when the core body temperature reaches 104°F, can damage the brain, heart, kidneys, and muscles in the body. It requires emergency treatment. See the Centers for Disease Control and Prevention’s Heat Related Illness page for these and other heat-related illness symptoms and treatment information.
As with all good things, moderation is best. Limit time in the sun and see a doctor if unusual growths or changes in the skin appear. Taking precautions, especially in sunny San Diego County, can still provide plenty of enjoyment in the sun.
Sources: American Academy of Dermatology Association, Types of Skin Cancer, https://www.aad.org/public/diseases/skin-cancer/types/common; American Cancer Society, Signs and Symptoms of Melanoma Skin Cancer, https://www.cancer.org/cancer/melanoma-skin-cancer/detection-diagnosis-staging/signs-and-symptoms.html; Ultraviolet (UV) Radiation, https://www.cancer.org/cancer/cancer-causes/radiation-exposure/uv-radiation.html#:~:text=UV%20rays%2C%20either%20from%20the,can%20also%20cause%20eye%20problems; Centers for Disease Control and Prevention (CDC), Heat Related Illness, https://www.cdc.gov/niosh/topics/heatstress/heatrelillness.html; CDC, UV Radiation, https://www.cdc.gov/nceh/features/uv-radiation-safety/index.html; U.S. Environmental Protection Agency (EPA), Skin Cancer: Sun Safety, https://www.cdc.gov/cancer/skin/basic_info/sun-safety.htm; EPA, UV Index, https://www.epa.gov/sunsafety/uv-index-1; Mayo Clinic, Heat Exhaustion, https://www.mayoclinic.org/first-aid/first-aid-heat-exhaustion/basics/art-20056651; Mayo Clinic, Heatstroke, https://www.mayoclinic.org/diseases-conditions/heat-stroke/symptoms-causes/syc-20353581; U.S. FDA, FDA Advances New Proposed Regulation to Make Sure That Sunscreens Are Safe and Effective, https://www.fda.gov/news-events/press-announcements/fda-advances-new-proposed-regulation-make-sure-sunscreens-are-safe-and-effective.
Graphics: Parker Jewish Institute, https://parkerinstitute.org/for-your-better-health-july-2020/; CDC, https://www.cdc.gov/cancer/skin/sunsafeselfie/index.htm