Frequently asked questions

What’s the difference between UVA and UVB light? Which causes cancer and which causes aging?

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 genetic defects, or mutations, that can lead to skin cancer as well as premature aging. Ultraviolet A (UVA): Has a longer wavelength, and is associated with skin aging. Causes tanning, and the shorter wavelengths of UVA also cause sunburn. There is no such thing as a safe or healthy tan. UVA radiation is proven to contribute to the development of skin cancer. UVA is connected to the “Broad-Spectrum Protection” you see on the labels of sunscreen products. Early sunscreens only protected against against UVB rays, but once it was understood how dangerous UVA rays were, sunscreen manufacturers began adding ingredients to protect you from both UVA and UVB across the broader spectrum. 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. 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 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. UVA can penetrate windows and cloud cover. Ultraviolet B (UVB): Has a shorter wavelength and is associated with skin burning. Penetrates and damages the outermost layers of your skin. Overexposure causes suntan, sunburn and, in severe cases, blistering. UVB is connected to the Sun Protection Factor (SPF) on labels of sunscreen products. The SPF number tells you how long the sun’s radiation would take to redden your skin when using that product compared to the time without sunscreen. Can damage your skin year-round, especially at high altitudes or on reflective surfaces like snow or ice. UVB can be filtered and does not penetrate glass.

What type of sunscreen is best: chemical (absorbing) sunscreen or physical (reflective) sunscreen?

Chemical Sunscreens work like a sponge, absorbing the sun’s rays. They contain one or more of the following active ingredients: oxybenzone, avobenzone, octisalate, octocrylene, homosalate, or octinoxate. These sunscreens tend to be easier to rub into your skin without leaving a white residue. Physical sunscreens (also known as mineral sunscreens) act like a shield. Sitting on the surface of your skin, they deflect the sun’s rays. They contain the active ingredients titanium dioxide, zinc oxide, or both. If you have sensitive skin, opt for this type of sunscreen. Regardless of which sunscreen you choose, the best sunscreen is the sunscreen that you actually use! What matters is ensuring broad spectrum protection (from both UVA and UVB rays), an SPF of 30 or higher and water resistance.

I’ve heard some ingredients of chemical sunscreen can be bad for you, is this true?

Further research is needed. A recent study by the FDA looked at four sunscreen ingredients and concluded that absorption of these ingredients into the body supported the need for additional safety data. However, the study noted that the data do not conclude that there are any effects on a person’s health and more research would be needed before it can be determined. Importantly, the study authors stated that individuals should continue to use sunscreen.

How much sunscreen should I use and how often do I need to apply it?

Apply enough sunscreen to cover all exposed skin. Most adults need about one ounce of sunscreen, enough to fill a shot glass, to fully cover their body. (Most people only apply 25-50 percent of the recommended amount of sunscreen). Don't forget about the tops of your feet, your neck, your ears, and the top of your head. Apply sunscreen to dry skin 15 minutes before going outdoors. Skin cancer can also form on the lips. To protect your lips, apply a lip balm or lipstick that contains sunscreen with an SPF of 30 or higher. When outdoors, reapply sunscreen approximately every two hours, or after swimming or sweating, according to the directions on the bottle.

What is SPF and what SPF do I need to use?

The Sun Protection Factor (SPF) number tells you how long the sun’s radiation would take to redden your skin when using that product compared to the time without sunscreen. UVB is connected to the Sun Protection Factor (SPF) on labels of sunscreen products. Dermatologists recommend using a sunscreen with an SPF of at least 30, which blocks 97 percent of the sun’s UVB rays. Higher-number SPF’s block slightly more of the sun’s UVB rays, but no sunscreen can block 100 percent of the sun’s UVB rays. High-number SPF’s last the same amount of time as low-number SPFs. A high-number SPF does not allow you to spend additional time outdoors without reapplication.

What should I look for when choosing a sunscreen?

Choosing the right sunscreen can help reduce the risk of skin cancer and early skin aging caused by the sun. The American Academy of Dermatology recommends choosing a sunscreen that states the following on the label: Broad spectrum: The words “broad spectrum” means that the sunscreen can protect your skin from both types of harmful UV rays (UVA and UVB). SPF 30 or higher: The American Academy of Dermatology recommends that you select a sunscreen with an SPF rating of 30 or higher. Water resistant: Dermatologists also recommend that you look for the words “water resistant”. This tells you that the sunscreen will stay on wet or sweaty skin for a while before you need to reapply. Water resistance lasts either 40 or 80 minutes. Not all sunscreens offer water resistance.

How do the free skin exams work?

If you or a loved one would like a free skin screening performed by a skin health professional, just visit the Sun Bus at one of its scheduled events and we will sign you up. These free screenings are provided on a first come, first serve basis when a healthcare professional is present. Check our Calendar of Events ( for a detailed list of future event locations and scheduled times a provider will be present.

Where can I find a print out with additional information about The Sun Bus?

The Sun Bus Informational booklet is available for download at HERE.

What types of events does The Sun Bus attend?

During the Spring, Summer, and Fall months, The Sun Bus attends large community and state-wide events, fairs, trade shows, and festivals. During the school year, The Sun Bus works with Colorado public and private schools to provide sun safety school-based education to children at every grade level. The Sun Bus also works with municipalities and businesses to deliver an inexpensive method to provide free skin cancer screenings to a population of residents or employees.

How do I get The Sun Bus to attend my event?

If you are interested in having The Sun Bus attend your event, please complete the Event Suggestion form located on the Calendar of Events page. You can also send a message with your request directly to Brittany Langevin at Our attendance is based on our availability and the Calendar for 2020 is filling up fast! Reach out to see if The Sun Bus is available for your event today!

How do I become a Volunteer Public Educator with The Sun Bus?

If you are interested in joining team Sun Bus by becoming a Volunteer Public Educator, please complete the Volunteer Public Educator sign-up.

How do I become a Volunteer Physician with The Sun Bus?

If you are interested in joining team Sun Bus by becoming a Volunteer Physician, please complete the Volunteer Physician sign-up located at

What are the most common skin cancers?

The three most common types of skin cancer are basal cell carcinoma, squamous cell carcinoma (both are often grouped in nonmelanoma skin cancers) and melanoma. Basal cell carcinoma (BCC) is usually found on the sun-exposed areas of the skin, such as the face, scalp, ears, arms and torso. It rarely spreads to other parts of the body, but can be locally destructive. BCCs are the most common form of skin cancer, with more than a million new cases diagnosed in this country each year. Squamous cell carcinoma (SCC) begins in the uppermost layers of the skin and is most commonly a result of lifelong sun exposure. A small percentage of SCCs have the potential to spread to other areas of the body. SCCs are the second most common skin cancer, with hundreds of thousands of new cases diagnosed in this country each year. Melanoma develops in the cells that make pigment in the skin. It is the most serious type of skin cancer. Melanoma can spread quickly through lymph nodes to the internal organs. But when it is diagnosed and treated early it has a high cure rate. Melanoma is the most common form of cancer for adults between 25-29 years old. According to the American Cancer Society, approximately 91,000 new cases of melanoma are diagnosed in the United States each year.

What are the warning signs of skin cancer?

Because skin cancers are caused by the uncontrolled growth of skin cells, the first presentation is usually a visible change in a person's skin. Consult a trained physician immediately if you observe any of these warning signs associated with common skin cancers: Basal cell carcinoma: Shiny nodule or pimple; a sore that won't heal; a scar-like area or rough red patches. Squamous cell carcinoma: Crusted red nodules (typically on sun-exposed skin but can also occur inside the mouth or the genitalia). Melanoma: A growing mole that changes shape, color or size; a mole that bleeds or is painful; a new "mole" that grows rapidly; a dark streak or black discoloration of the fingernail.

What are the treatments for skin cancer?

Nonmelanoma skin cancers are some of the most treatable cancers. When melanoma is caught and treated early (before it spreads to the lymph nodes), it is also highly curable. The goal of treatment for skin cancer is to remove, or excise, all of the cancer. Typically, the first line therapies are surgical. Non-surgical treatments may be an option in some cases. The type of surgical treatment used depends on the type, size, depth and location of the tumor. In most cases, the procedure is done on an outpatient basis. The most common surgical procedures to remove cancerous areas of the skin are: Mohs micrographic surgery: A "stepwise" excision performed by a dermatologist with special training in the procedure. Thin layers of skin are removed in stages and examined under a microscope for the presence of cancer cells. The process is repeated until no cancer cells remain. Mohs is used for certain types of skin cancer on the head, neck, feet and genitalia. It offers the highest cure rates (up to 99 percent for certain skin cancers) and leads to the best possible cosmetic result. Standard excision: The skin cancer is excised along with a standard amount of normal-appearing skin. This may be used for melanoma and small nonmelanoma skin cancers on the torso and extremities. Curettage and electrodessication: Involves the scraping the cancerous growth with a curette and cauterizing the area to destroy residual tumor and to control bleeding. This may be effective for a subtype of basal cell carcinoma and very early squamous cell carcinoma. Radiation, chemotherapy or immunotherapy may be necessary for advanced cases of skin cancer or when patients are unable to have surgery. Learn more about treatment for melanoma skin cancers.

Is skin cancer becoming more common? What are some of the risk factors?

The incidence of skin cancer has been increasing quickly for the past few years. One in two men and one in three women will develop nonmelanoma skin cancer in their lifetime. Once a patient has a nonmelanoma skin cancer, there is a much higher risk of developing more skin cancers. The risks factors for developing nonmelanoma skin cancer include: Exposure to arsenic, Fair skin, Heavy UV exposure, History of radiation therapy, Immunosuppression, Indoor tanning bed use, Multiple blistering sunburns, Northern European ancestry, Prior skin cancer diagnosis, Some forms of the HPV virus Individuals at higher risk of melanoma include those with: Red or Blonde Hair, Blue or green eyes, Many atypical moles, a first-degree relative with a history of melanoma, a previous diagnosis of melanoma or non-melanoma skin cancer(s)

What can we do to protect ourselves from the sun?

Sun exposure can damage your skin during any season, but summer rays are more harmful and can raise the risk of developing skin cancer. Tips for smart sun care include: Use sunscreen daily. Look for a "broad spectrum" sunscreen that protects against both UVB light and UVA rays. Opt for water-resistant products with a sun protection factor (SPF) of at least 30 on an average day, whether bright or cloudy. Choose a higher SPF for outdoor activities, especially swimming and exercise. Apply sunscreen liberally and reapply at least every two hours and after swimming or sweating. Wear sunglasses, use SPF 15-30 lip balm and reapply often. Wear sun-protective clothing. Minimize sun exposure between 10 a.m. and 4 p.m. Seek shade. Avoid tanning bed use. See your dermatologist for a yearly skin exam.

Myth or Fact? The higher the SPF the better.

There are two types of Ultraviolet (UV) radiation that we worry about, UVA and UVB. SPF refers to the ability of sunscreen to protect against UVB rays. UVA rays age your skin causing wrinkles and age spots, and can pass through glass. UVB rays cause sunburns (B for burn!) and are blocked by window glass. Both UVA and UVB cause skin cancer. Sunscreens are products that reflect or absorb radiation so that it can’t damage our skin. SPF (Sun Protection Factor) refers to the ability of the product to protect against UVB rays. The numbers aren’t logical (the relationship is not linear), i.e. SPF 30 is not double the protection of SPF 15. SPF 15 protects against 93% of the UVB radiation that hits your skin, SPF 30 protects against 97% of the UVB radiation, and SPF 50 blocks out 98% of the UVB radiation. If you use products with SPF >50 you will get a negligible increase in protection from UVB radiation. Buy a sunscreen that is at least SPF 30, but don’t bother spending extra money on SPF greater than 50, because you won’t get much additional benefit. It’s also important to make sure that your sunscreen protects against both UVA and UVB radiation. Look on the bottle to make sure it says “broad spectrum” protection against UVA and UVB. This is a striking photo from the New England Journal of Medicine of a man with extensive UVA damage to the left side of his face from sun exposure while driving a truck for 28 years. You can see how the left side of his face is thickened and filled with wrinkles from photodamage.

Myth or Fact? You don’t need that much sunscreen to be protected.

The Shotglass Rule for Sunscreen. The amount of sunscreen researchers use when they study the product is 2mg of sunscreen for each square centimeter of exposed skin. Think about that for a second… that’s a lot of sunscreen! Most people apply only 25-50% of the recommended amount of sunscreen. A good rule of thumb is the shotglass rule. The amount of sunscreen that fills a shotglass (one ounce, or 30mL) is how much you need to cover exposed areas of the body for an adult. Since most bottles of sunscreen are 90-150mL, they should be used up after 3-5 applications of sunscreen. If you put on less sunscreen, you will still get some protection, but you won’t get the full SPF protection that is labeled on the bottle. Sunscreens should last for at least three years – however, if you are using it properly, you shouldn’t have to worry about the expiry date because you will have consumed your bottle before then.

Myth or Fact? I don’t need sunscreen on cloudy days.

UV rays are present on cloudy days and winter days, and up to 80% of UV rays can still penetrate the skin when it’s cloudy. A better indication of whether or not you need sun protection is to look at the UV index on your local weather report. The UV index looks at how much radiation we are receiving from the sun. A UV index greater than 3 indicates a moderate risk of harm from sun exposure. If the UV index is 3 or greater, put on sunscreen and stay out of the sun during the peak times of 11am to 4pm, when the UV rays are the strongest. Plan your outdoor activities before 11am and after 4pm if possible.

Myth or Fact? If I put on sunscreen, I can safely sit in the sunshine.

Sunscreen is meant to provide protection during periods of sun exposure. It shouldn’t be used as a way to increase the amount of time you can spend in the sun. Even if you put on sunscreen, you should still wear a hat, stay in the shade, wear protective clothing, and take breaks from the sun. Apply sunscreen early, about 20-30 minutes before sun exposure to allow the product to form a protective film on your skin. Reapply every couple of hours or after swimming and sweating – even if it’s labelled water resistant! There are two ways that sunscreens work – via physical block or chemical block. Physical block sunscreens work by reflecting or blocking UV rays. Chemical sunscreens work by absorbing UV rays so that they can’t damage your cells.

Myth or Fact? Spray on sunscreens are the same as regular sunscreens.

There are two main concerns with spray on sunscreens: accidentally breathing in the products and adequate protection. When we spray sunscreen, the particles are aerosolized and we can breathe them in. We do not have enough data on whether or not these particles are safe, especially in children. It is possible that they could trigger asthma attacks or allergic reactions. Some organizations recommend avoiding spray on sunscreen in children (unless no other product is available) due to the lack of safety data. The other concern about spray on sunscreens is that it is difficult to tell if you’ve put on enough, possibly resulting in less protection compared to the cream form. How you spray on the sunscreen and environmental factors like the wind can also affect how much sunscreen gets on your skin. If you decide to use spray on sunscreen, avoid inhaling it as much as possible. Don’t spray it in enclosed areas, and be aware around open flames (BBQs, candles) because some sprays are flammable. It is best to spray the product onto your hands and then rub it onto your skin, particularly when applying to your face. This reduces inhalation and provides better coverage. Apply lots, because it’s harder to assess coverage with sprays.

Myth or Fact? Some sun is good for me.

Myth! The biggest risk factor for developing skin cancer is exposure to harmful UV radiation. There is no safe way to tan. Every time you tan, you damage your skin. We know that UV radiation from the sun causes skin cancer. It is a known carcinogen. Protect yourself!