Skip to Main Content

We have a new app!

Take the Access library with you wherever you go—easy access to books, videos, images, podcasts, personalized features, and more.

Download the Access App here: iOS and Android



  • Photoprotection measures include seeking shade during the peak ultraviolet (UV) B hours of 10:00 AM to 2:00 PM and the use of high sun protection factor (SPF) broad spectrum sunscreen, clothing, wide-brimmed hat, and sunglasses.

  • UV induces skin aging and skin cancer, but using sunscreen may slow down skin aging and reduce the risk of developing skin cancer.

  • Photoprotection in children is essential and its importance should be taught from childhood.

  • Although oral photoprotection cannot substitute for topical sunscreen, it may serve as a secondary measure to prevent skin damage from solar radiation.

  • UV protection factor is a UV protection rating for fabrics. Several chemical treatments can increase a fabric’s natural UV protection factor.

  • Many types of glass have very good UVA2 and UVA1 protection (up to 380 nm).

  • Sunglass standards, mandatory in Australia and voluntary in the United States, specify a maximum percentage of light allowed to be transmitted and a minimum vertical dimension of sunglasses.

The earth is constantly exposed to radiation from the sun, which is indispensable for life. Radiation includes ultraviolet, visible, and infrared rays. Ultraviolet (UV) light B, which accounts for 5% to approximately 10% of the UV light that reaches the surface of the earth, is high in energy and induces erythema. UVA is composed of UVA2 (320 nm to approximately 340 nm) and UVA1 (340 nm to approximately 400 nm). UVA1 is low energy and accounts for 95% of the UV that reaches the surface of the earth because it can penetrate through clouds and glass windows, and is not obstructed by the ozone layer For this reason, UVA1 is present all the time, regardless of cloud cover or other obstruction. Although UVA1 may not cause erythema, it is more likely to cause pigmentation than any other wavelength. In addition, it induces reactive oxygen species (ROS), which cause damage to blood vessels, collagen fibers, and elastic fibers located deep under the skin, and are involved in skin aging. Infrared rays also affect skin and trigger skin aging by increasing skin temperature.1

With increased attention to physical fitness and outdoor recreational activities, daily exposure to sunlight is common. In addition, longer life expectancy has increased the amount of lifetime exposure to sunlight. Although sun exposure may have beneficial effects, such as mood elevation and vitamin D3 photosynthesis, unwanted effects are well known. Acute effects of sun exposure include sunburn and delayed tanning. Acute responses to sunlight result from the direct influence on biologic chromophores like DNA. These responses release proinflammatory cytokines, enzymes, and immunosuppressive factors. These effects are mediated by ROS, which are generated by UVB, UVA and visible light as well as and infrared rays. Chronic responses to sunlight are a result of accumulation of damage and decreased ability to repair. Chronic sun exposure is strongly associated with photoaging, actinic keratoses, and skin cancers. Complete avoidance of sun exposure is neither necessary, practical, nor would ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.