Skin Deep

Sun protection: The difference between UVA vs. UVB and why it matters

Wearing sunscreen can help prevent skin cancer, and there are big differences between UVA and UVB rays.
Wearing sunscreen can help prevent skin cancer, and there are big differences between UVA and UVB rays. TNS

More and more people are taking extra precautions to limit sun exposure and keep their skin protected when outdoors.

But many people still believe going to an indoor tanning bed is safer than spending time in the sun. In reality, the exact opposite is true. The reason has to do with the differences between UVA and UVB rays.

UVA Rays

Tanning beds utilize UVA rays. UVA light has the longest wavelengths of the three types of UV rays that the sun emits, with UVC rays being the shortest. UVC rays are so short that they are unable to penetrate the earth’s atmosphere, leaving only UVA and UVB rays that are able to reach our skin. UVA rays are used in tanning beds because they lead to skin darkening but do not cause the visible skin redding or “sunburn” associated with UVB rays.

The problem with UVA rays is that they are more damaging to the skin than UVB rays. This is because UVA light can reach deeper layers of skin than UVB rays, causing damage to the deeper dermal layers. Because your skin does not turn red, you do not realize the damage that UVA is causing. UVA is a major cause of DNA damage and mutations, which lead to skin cancer, skin aging and unsightly sun spots.

UVB Rays

UVB rays are shorter than UVA and longer than UVC. UVB exposure will cause a painful sunburn when you’ve been out in the sun for too long, so you have a warning sign that you need to give your skin a break. UVB rays can also lead to skin cancer and skin aging but UVB rays do not go as deeply into the dermis of skin like UVA rays, so the damage is a bit less than UVA.

Protecting Your Skin

Sun avoidance, broad-spectrum sunscreen use, antioxidants and retinoids are the only ways to protect your skin from the ravages of UV radiation. However, if you have to choose between going out in the sun or using a tanning bed, choose the sun. Keep in mind that the sun emits both UVB and UVA rays, so it’s still important to keep your skin protected with a broad-spectrum SPF sunscreen when you’re going to be outside.

As a dermatologist I would prefer that you protect your skin at all times. However, I have many patients who want to be tan so I have to make some concessions to minimize the damage they will get from the sun. If you want to expose your skin to the sun to get vitamin D or a tan, here are a few tips to remember that will help protect your skin:

  • You don’t need to stay out in the sun for hours to get the vitamin D your body needs. In fact, exposing your arms and legs to the sun for 10 to 15 minutes is plenty to do the trick.
  • Try using a natural vitamin D UV activation sensor. This sensor will change colors once it’s been in the sun long enough for your body to have stimulated vitamin D synthesis, so you’ll know exactly when it’s time to get out of the sun!
  • Use sunscreen on your face and neck at all times to prevent wrinkles, sagging and sun spots.
  • After 15 minutes, apply a SPF to the rest of your body.
  • Reapply the sunscreen every 45 minutes that you are in the sun and after going in the water.
  • Apply a topical antioxidant to your skin to protect it from damage such as Vitamin C or Argan Oil
  • Take an oral antioxidant supplement such as polypodium leucotomos in Heliocare to prevent damage.
  • Drink green tea to boost the skin’s antioxidant activity
  • At night, use a retinoid such as retinol to minimize the sun’s damage. Retinoids turn off some of the bad genes turned on by ultraviolet light.
  • Avoid eating limes, celery or figs in the sun. These make your skin more sun sensitive.

SummaryAll UV light is bad for the skin because it causes DNA mutations and damage to cells. UVA light is more damaging than UVB because it penetrates deeper. Try to avoid sun exposure, but if you can't (Or won't), follow these tips to protect your skin. May is melanoma month so be sure and schedule a skin cancer check with your dermatologist. Catching a melanoma early can save your life. You can find a board certified dermatologist at

Dr. Leslie Baumann is a board-certified dermatologist and CEO of Baumann Cosmetic & Research Institute in Miami.