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We know that UVA and UVB, which are part of the ultraviolet spectrum, can be deleterious for the skin. That is why sunscreens incorporate UV filters to protect against those rays. Nonetheless, infrared is also part of the sunlight spectrum. Is it also bad for our skin? Let’s see what the science says!
If you are interested in knowing more about UVA and the UVB radiation, you can access my Ultraviolet and the Skin series which deals with:
- what they are (Part 1),
- what their effects on the skin are (Part 2),
- how to protect against them (Part 3),
- and how much (theoretical) daily exposure to avoid skin aging.
Also, my other series called Sunscreens and Your Skin tells you:
- how sunscreens protect against UV rays (Part 1),
- what the differences are between organic and inorganic UV filters (Part 2),
- and what the information like SPF, PPD, PA+, Broadspectrum… on the packaging mean (Part 3).
🇬🇧 Is Infrared Light Bad For Your Skin?
I’d like first to remind you a bit about the effects of the ultraviolet rays on the skin before going further to the infrared rays.
1. UVA and UVB radiation
UVA and UVB only counts for about 3% of the total sunlight reaching Earth’s surface.
FYI, visible light accounts for 44% at ground level and the remainder is infrared.
Of the ultraviolet radiation that passes the Earth’s atmosphere, more than 90% is UVA and less than 10% is UVB.
Nonetheless, for years, sunscreens commercially available had only been focusing on protecting against the UVB radiation. The reason was that those rays were causing sunburns, a short-term or acute visible reaction. When the long-term (chronic) damage caused by UVA were highlighted years after, especially skin cancer, photo-aging, and immune suppression, manufacturers started incorporating UVA filters in their sun products (1). Nowadays, improved filters against UVA and UVB rays available on the market have a broadspectrum protection.
Although the impacts of UV radiation on the skin have been extensively studied over the years, the consequences of infrared radiation (IR) have received far less attention.
2. Infrared radiation (IR)
IR accounts for about 50% of the solar radiation reaching the Earth’s surface.
It is divided into three ranges (in nanometer, nm):
- IR-A (760nm–1400nm),
- IR-B (1400nm–3000nm),
- and IR-C (3000nm – 1 mm).
Those radiations can penetrate deeply into the skin, especially for IR-A, as seen on the image.
Exposure to IR is perceived as heat (2).
In vitro (cell culture samples) and in vivo (in real skin samples of humans or animals) studies have shown that IR has beneficial and deleterious effects on the skin:
- On one hand, studies show that IR, and especially IR-A induces skin wrinkling, increases UV-induced wrinkle formation and decreases the antioxidant level of human skin through an oxidative stress response leading to premature photoaging (3,4).
On the other hand,
- it has been demonstrated that it can induce skin tone improvement, reduce wrinkles and increase the skin elasticity by augmenting the amount of collagen and elastic fibers produced by the skin (5,6). For that purpose, it is used in skin rejuvenation therapies.
- IR is also well known to promote healing processes of wounds for decades now and is also used in therapies on patients (7).
Feeling a bit lost?
==> To clear things a bit up, a recent 2015 review exposed that many studies showing negative impacts of IR irradiation used artificial light sources which intensity is much greater than that found in natural sunlight (beyond 100 mW/cm2 which would cause heat pains on exposed skin). For the authors of the review, those studies are thus not representative of real-life IR irradiation and must be taken carefully (8).
As mentioned in my this article, where I have already briefly talked about IR, more studies must be conducted in realistic IR exposure to fully assess the deleterious effects of IR but as of today, science is not positive about them.
Nonetheless, some commercial brands, for example Make P:rem with their UV Defense Me Blue Ray Sun Gel, have already added protection against IR by cooling down the skin to maximize photoprotection.
3. What to remember?
- Infrared radiation is part of the invisible spectrum of sunlight, like ultraviolet rays.
- It is divided into 3 ranges, IR-A, IR-B and IR-C. IR-A can penetrate the skin deeper than UV rays and is the most concerning IR.
- However, more studies are needed to positively show that IR affects the skin negatively under real-life conditions, as actual artificial light used in testing is not representative of the IR natural sunlight exposure.
Do you specifically protect your skin against infrared rays? Why? Leave a comment below!
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