What type of radiation affects the skin? Why is it important?

With the arrival of good weather and the timid departure from confinement, the first sun exposures will begin. But do we know how to protect our skin? We would like to share with you some messages that will help to clarify some doubts and possibly modify some attitudes. Don’t gamble with the health of your skin! Go to your dermatologist!

The sun emits different types of radiation: only visible light, infrared light and part of the ultraviolet radiation (UVR): A and B, reach the earth’s surface. The rest of the solar radiation is stopped by the ozone layer.

Most of the harmful effects on the skin are produced by UVR. UVR and visible light are less attenuated by the ozone layer and reach the earth’s surface to a greater extent; UVBR reaches the earth’s surface to a lesser extent. UVBR is responsible for burns; UVR is primarily responsible for photoaging. Both are implicated in skin cancer.

The risk of skin cancer is mainly attributed to UVRB. Although RUVA is less mutagenic, as I have mentioned, it reaches the earth’s surface in greater quantities, so its role in skin cancer cannot be underestimated; in addition, some RUVA can pass through car glass, clothing and penetrates deeper (to the dermis). I also like to remember that tanning booths for “aesthetic” purposes emit UVR.

Chronic UVR exposure is associated with cancer of the “squamous” type (actinic keratoses, epidermoid carcinoma), while high and intermittent doses of UVR (typical of sunburn) have been associated with melanoma and basal cell carcinoma.

Both UVB and UVR are implicated in skin cancer: protection against both is necessary. UVR is the main cause of photoaging.

Visible light (VL) has not been implicated in skin cancer, but it has been implicated in skin hyperpigmentation and melasma (of great aesthetic concern). Blue light, so fashionable lately, is a type of visible light that also originates from screens of electronic devices and fluorescent lamps. Not all people have the same tendency to pigment, so protection against VL will be more relevant in people with this predisposition due to their skin type. This hyperpigmentation effect depends on high-dose radiation and irradiance, and this is observed in sunlight, but is not emitted by screens. There is no standardized way to measure visible light protection.

Infrared radiation (IR) is perceived by the skin as heat and can penetrate deeper (epidermis, dermis and subcutaneous tissue). It has not been linked to skin cancer, but appears to be implicated in photoaging through oxidative stress. There is also no standardized way to measure infrared protection.

The effects of LV and RI are cosmetic: hyperpigmentation and photoaging.

The effects of LV depend mainly on that emitted by the sun. As far as is known today, the effects of LV emitted by screens are marginal.