DEAR MAYO CLINIC: A friend has had several small skin cancers removed, and that made me wonder if I'm at risk, too. What everyday habits can help reduce my risk of skin cancer?

ANSWER: Whether skies are clear or overcast, your skin is exposed to ultraviolet (UV) radiation from the sun. UVB rays are the primary cause of sunburn, while UVA rays penetrate more deeply, contributing to premature aging, such as fine wrinkles and sunspots. Both forms of UV radiation increase the risk of skin cancer.

A tan is not a sign of health; it's evidence of skin injury. There's no safe way to tan in the sun or with indoor tanning. Fortunately, daily habits can protect your skin and reduce your risk of skin cancer.

Use sunscreen consistently. Choose a broad-spectrum sunscreen that protects against both UVB and UVA rays with an SPF of at least 30. Be aware of the expiration date and replace your sunscreen regularly. Keep it out of the heat and direct sunlight, which can degrade its effectiveness.

Spray sunscreens are typically easier to apply to hairy skin. Makeup also can contain sun-protective ingredients, but it should meet the same minimum standard of a broad-spectrum sunscreen and an SPF of at least 30. Sunscreens may contain organic or inorganic ingredients, or a combination of both.

Inorganic (mineral) sunscreens contain minerals such as titanium dioxide and zinc oxide and provide excellent, broad-spectrum protection. These ingredients tend to be thicker and may leave a whitish residue on your skin.   

Organic (chemical) sunscreen filters are more common and tend to be lighter, easier to spread and less visible on the skin, but they may not have as much UVA protection as mineral options.

The Food and Drug Administration recently announced its proposal to add a new organic sunscreen ingredient, bemotrizinol (BEMT), to its approved list for use in the U.S. BEMT provides protection against both UVA and UVB, and it has low levels of absorption through the skin into the body. This is exciting news because the U.S. doesn't have as many approved filters compared to other countries.

Apply sunscreen whenever you're outdoors — even on cloudy days, when up to 80% of harmful rays penetrate the clouds. When applying sunscreen:

• Don't forget places like the tops of your ears and feet, the back of your neck, and areas where a beard might not be as thick. 
• Reapply sunscreen every two hours.
• Remember to reapply more often with water exposure or sweating because this reduces how long the sunscreen remains effective. Water-resistant sunscreen provides protection for about 40 to 80 minutes. 
• Apply more sunscreen than you think. Most people apply only a quarter to half of the amount needed to reach the advertised SPF on the product label. A simple strategy is to apply a full layer, then repeat to create a "double coat" to ensure adequate coverage. 

Wear photoprotective clothing. Long-sleeved shirts, pants, wide-brimmed hats and sunglasses provide consistent protection without the need for reapplying sunscreen. Not all clothing blocks the same amount of UV rays. Test it by holding it up to the light. If you can see the light through the clothing, you'll know that UV rays can pass through, too.

Many brands now offer lightweight, breathable clothing with built-in ultraviolet protection rated with an ultraviolet protection factor (UPF). For water activities, rash guards offer convenient, reliable sun protection. Tops are available in short- and long-sleeved styles, with or without hoods. 

Avoid intentional tanning. Indoor tanning significantly increases the risk of cancer. Tanning beds emit intense UV radiation and can increase melanoma risk by 20% with just one session. Using indoor tanning before age 35 can increase melanoma risk by 75%. Dermatologists see patients in their 30s with multiple skin cancers and advanced sun damage after extensive tanning bed use in their teens and 20s.

If you want a bronzed glow without the risk of UV rays, sunless tanning products are a safe alternative. Spray tans and lotions containing dihydroxyacetone can create the appearance of tanned skin without UV exposure.

Be mindful of peak sun hours. If you love being outdoors, whether it's hanging at the beach, working in the garden, hiking on a fall day or skiing down a mountain, it's wise to use a combination of sun-protective behaviors, including sunscreen, photoprotective clothing and seeking shade when possible. Consistent sun-protective behaviors will substantially reduce your risk of skin cancer while allowing you to enjoy time outdoors safely.

Steven Nelson, M.D., Dermatology, Mayo Clinic, Phoenix