Fri, Jul 21, 2017 - Page 4 News List

Sun protection urged, even while inside

By Lee I-chia  /  Staff reporter

A dermatologist yesterday urged people to prevent overexposure to sunlight not only when participating in outdoor activities, but also while indoors.

Skin damage from overexposure to sunlight is a concern, as Taiwan is in the subtropics and sunlight can be strong throughout the year, said Hou Yuan-yue (侯源裕), a dermatologist at Chi Mei Medical Center.

Overexposure can cause the skin to age faster and increase the risk of skin disorders, including skin cancer, he said.

Sunlight brings ultraviolet (UV) radiation with a wavelength spectrum from 200 nanometers to 400 nanometers and can be divided into three types: UVC, UVB and UVA rays, he said.

UVA radiation, which has wavelengths from 320 nanometers to 400 nanometers, penetrates deeper into the skin, causing it to redden or tan, and is the main cause of skin aging, Hou said.

However, UVB radiation, with wavelengths from 290 nanometers to 320 nanometers, can penetrate into the epidermis — the top layer of the skin — causing damage to cells, sunburn and increased risk of skin cancer, he said, adding that UVC is completely absorbed by ozone in the atmosphere.

Many people mistakenly think sun protection is not needed on cloudy days or while indoors, Hou said, adding that the skin can be exposed to UV radiation indoors and outdoors, on both sunny and rainy days all year round.

“UVA radiation can penetrate through clouds and windows, so sunlight protection is needed every day,” he said, adding that people can use SPF15 sunscreen for daily protection, reapplying it about every three hours.

People planning to go outdoors for extended periods can be exposed to 20 to 25 times more UV radiation than if they remained indoors, so they are advised to apply higher SPF sunscreens, Hou said.

SPF25 PA+++ is ideal for the outdoors, Hou said.

Moreover, people should use “water resistant” or “waterproof” sunscreens if they plan to participate in water activities, he said, adding that these products might only be useful for 40 minutes and 80 minutes respectively after the skin becomes wet.

The damaging effects of UV radiation accumulate over the years and studies have shown that accumulated exposure at age 20 can be 50 to 75 percent of lifetime exposure, so proper protection at a young age can reduce the risk of cancer.

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