Should I Wear Sunscreen Indoors

Addressing the Need for Indoor Sun Protection

6 min read

feb 5, 2024 - by felix tajanko
LIFE STYLE
Should I Wear Sunscreen Indoors

Addressing the Need for Indoor Sun Protection

6 min read

feb 5, 2024 - by felix tajanko
LIFE STYLE
In recent years, the concern for sun damage while indoors has grown considerably, and dermatologists, estheticians, and medical professionals alike can agree that sun protection should be a crucial component of everyone’s skin health measures. UV radiation accounts for up to 90% of extrinsic damage incurred on the skin.1 The best-known way to prevent this damage to the skin is by using sunscreen. In this article, we will explore why it's necessary to wear sunscreen indoors, the benefits of doing so, tips for introducing sunscreen to your routine, and the other ways you can protect your skin while indoors.
In recent years, the concern for sun damage while indoors has grown considerably, and dermatologists, estheticians, and medical professionals alike can agree that sun protection should be a crucial component of everyone’s skin health measures. UV radiation accounts for up to 90% of extrinsic damage incurred on the skin.1 The best-known way to prevent this damage to the skin is by using sunscreen. In this article, we will explore why it's necessary to wear sunscreen indoors, the benefits of doing so, tips for introducing sunscreen to your routine, and the other ways you can protect your skin while indoors.

Do You Need to Wear Sunscreen Indoors?

While many people diligently apply sunscreen for outdoor activities, the concept of wearing it indoors may seem unnecessary. However, certain types of ultraviolet (UV) rays can penetrate glass windows, leading to skin damage over time. These UV rays may be split up into 3 different categories – UVA, UVB, and UVC. They are differentiated by the predominant wavelengths of UV that they carry, with shorter wavelengths (like UVC) carrying more energy.
  • Ultraviolet C (UVC) has the shortest wavelength and the most energy among UV rays. Fortunately, most UVC rays are absorbed by the Earth's atmosphere and, as a result, do not reach the surface. Because of this, their direct effects on the skin are minimal. However, exposure to artificial sources of UVC, such as certain types of lamps and equipment used in medical and industrial settings, can be harmful and may cause skin damage. Additionally, the Earth’s eroding atmosphere may eventually require us to protect ourselves from this type of UV in the future.
  • Ultraviolet B (UVB)
    or UVB radiation has a middling wavelength between the various types of UV rays and thus has more immediate and direct effects on the skin, owing to their ability to penetrate the ozone layer and reach the Earth’s surface. UVB rays are the variety that most manufacturers look out for in designing products such as windows, sunglasses, or sunscreen due to their capacity to cause sunburn and direct damage to DNA.2
  • Ultraviolet A (UVA) or UVA radiation has the longest wavelength, allowing it to penetrate deep into the dermis (skin’s middle layer); however, it also carries the least amount of energy. With these unique properties, long-term UVA exposure becomes necessary for its damage to become visible. UVA rays are primarily responsible for premature skin aging as they lead to collagen degradation and increased senescence
    , causing wrinkles, fine lines, and a loss of skin elasticity.3 They can also contribute to the development of skin cancer over time, albeit to a lesser degree than UVB.4
With this perceived lack of danger, there are fewer protections against UVA, particularly indoors. This indoor UV exposure is more significant than one might expect, as up to 60 percent of UVA rays can penetrate glass. Furthermore, while windshields are treated against UVA, side and rear windows generally are not [5]. This has led to the discovery that approximately 74 percent of malignant melanoma appeared on the left side of men, corresponding with sun exposure while driving [6]. Even by sitting at your desk or in your car, you may be slowly accumulating sun damage through constant exposure to UVA. Therefore, wearing sunscreen indoors, especially near windows, becomes crucial for ongoing skin protection.

Do You Need to Wear Sunscreen Indoors?

While many people diligently apply sunscreen for outdoor activities, the concept of wearing it indoors may seem unnecessary. However, certain types of ultraviolet (UV) rays can penetrate glass windows, leading to skin damage over time. These UV rays may be split up into 3 different categories – UVA, UVB, and UVC. They are differentiated by the predominant wavelengths of UV that they carry, with shorter wavelengths (like UVC) carrying more energy.
  • Ultraviolet C (UVC) has the shortest wavelength and the most energy among UV rays. Fortunately, most UVC rays are absorbed by the Earth's atmosphere and, as a result, do not reach the surface. Because of this, their direct effects on the skin are minimal. However, exposure to artificial sources of UVC, such as certain types of lamps and equipment used in medical and industrial settings, can be harmful and may cause skin damage. Additionally, the Earth’s eroding atmosphere may eventually require us to protect ourselves from this type of UV in the future.
  • Ultraviolet B (UVB)
    or UVB radiation has a middling wavelength between the various types of UV rays and thus has more immediate and direct effects on the skin, owing to their ability to penetrate the ozone layer and reach the Earth’s surface. UVB rays are the variety that most manufacturers look out for in designing products such as windows, sunglasses, or sunscreen due to their capacity to cause sunburn and direct damage to DNA.2
  • Ultraviolet A (UVA) or UVA radiation has the longest wavelength, allowing it to penetrate deep into the dermis (skin’s middle layer); however, it also carries the least amount of energy. With these unique properties, long-term UVA exposure becomes necessary for its damage to become visible. UVA rays are primarily responsible for premature skin aging as they lead to collagen degradation and increased senescence
    , causing wrinkles, fine lines, and a loss of skin elasticity.3 They can also contribute to the development of skin cancer over time, albeit to a lesser degree than UVB.4
With this perceived lack of danger, there are fewer protections against UVA, particularly indoors. This indoor UV exposure is more significant than one might expect, as up to 60 percent of UVA rays can penetrate glass. Furthermore, while windshields are treated against UVA, side and rear windows generally are not [5]. This has led to the discovery that approximately 74 percent of malignant melanoma appeared on the left side of men, corresponding with sun exposure while driving [6]. Even by sitting at your desk or in your car, you may be slowly accumulating sun damage through constant exposure to UVA. Therefore, wearing sunscreen indoors, especially near windows, becomes crucial for ongoing skin protection.

Benefits of Wearing Sunscreen Indoors

Wearing sunscreen indoors is not just a preventative measure against potential skin damage; it offers several benefits. First and foremost, it protects against the UVA rays that contribute to premature aging and skin cancer. Prolonged and unprotected exposure to UV rays can trigger a breakdown of key structural proteins in the skin, namely collagen and elastin. Together, collagen and elastin form a network of fibers that keep the skin firm and smooth. Collagen provides a scaffold for the skin, while elastin allows the skin to maintain its shape and bounce back after being stretched.7 Their breakdown leads to the accelerated development of fine lines, wrinkles, dark spots, and sagging skin.
Wearing sunscreen indoors, provides a vital layer of protection against the constant UV radiation. As a result, the UV rays cannot reach and break down the collagen and elastin in the skin, allowing your skin barrier to sustain its strength.Broad-spectrum sunscreen is also able to significantly reduce the risk of developing skin cancer due to sun damage. UV radiation from the sun damages DNA in skin cells, which can lead to DNA mutations, some of which may cause uncontrolled cell growth.Also important in the digital era is sunscreen’s ability to block blue light or HEV light from penetrating your exposed skin and causing effects such as premature skin aging and skin hyperpigmentation
.8 It has been found that sunscreens containing zinc and iron oxides have been effective at reducing levels of blue light reaching the skin.9 Regular use of a broad-spectrum sunscreen, such as
OneSkin’s non-nano zinc oxide mineral sunscreen (OS-01 SHIELD and the upcoming OS-01 BODY SPF), can help protect against UV damage and repair the effects of UV aging.

Benefits of Wearing Sunscreen Indoors

Wearing sunscreen indoors is not just a preventative measure against potential skin damage; it offers several benefits. First and foremost, it protects against the UVA rays that contribute to premature aging and skin cancer. Prolonged and unprotected exposure to UV rays can trigger a breakdown of key structural proteins in the skin, namely collagen and elastin. Together, collagen and elastin form a network of fibers that keep the skin firm and smooth. Collagen provides a scaffold for the skin, while elastin allows the skin to maintain its shape and bounce back after being stretched.7 Their breakdown leads to the accelerated development of fine lines, wrinkles, dark spots, and sagging skin.
Wearing sunscreen indoors, provides a vital layer of protection against the constant UV radiation. As a result, the UV rays cannot reach and break down the collagen and elastin in the skin, allowing your skin barrier to sustain its strength.Broad-spectrum sunscreen is also able to significantly reduce the risk of developing skin cancer due to sun damage. UV radiation from the sun damages DNA in skin cells, which can lead to DNA mutations, some of which may cause uncontrolled cell growth.Also important in the digital era is sunscreen’s ability to block blue light or HEV light from penetrating your exposed skin and causing effects such as premature skin aging and skin hyperpigmentation
.8 It has been found that sunscreens containing zinc and iron oxides have been effective at reducing levels of blue light reaching the skin.9 Regular use of a broad-spectrum sunscreen, such as
OneSkin’s non-nano zinc oxide mineral sunscreen (OS-01 SHIELD and the upcoming OS-01 BODY SPF), can help protect against UV damage and repair the effects of UV aging.

How Often to Reapply Sunscreen Indoors

Reapplying sunscreen is as essential indoors as it is outdoors. The general recommendation is to reapply sunscreen every two hours, especially if you're near windows receiving direct sunlight. However, if you are away from windows or in a less sun-exposed environment, reapplying every 3-4 hours can be sufficient. The length of time that an application of sunscreen lasts is highly dependent on the individual, the activities they will be doing, and the SPF level they choose to apply. Particularly because sunscreen is so likely to rub or wash off, it is recommended that individuals apply sunscreen every 4 to 6 hours to maintain an effective barrier against UV rays.10 With it being so easy for the effectiveness of sunscreen to diminish, the only surefire way to maintain protection against sun damage with sunscreen is to regularly replenish and reapply. Remember, using a broad-spectrum sunscreen provides comprehensive protection against both
UVA and UVB rays.

How Often to Reapply Sunscreen Indoors

Reapplying sunscreen is as essential indoors as it is outdoors. The general recommendation is to reapply sunscreen every two hours, especially if you're near windows receiving direct sunlight. However, if you are away from windows or in a less sun-exposed environment, reapplying every 3-4 hours can be sufficient. The length of time that an application of sunscreen lasts is highly dependent on the individual, the activities they will be doing, and the SPF level they choose to apply. Particularly because sunscreen is so likely to rub or wash off, it is recommended that individuals apply sunscreen every 4 to 6 hours to maintain an effective barrier against UV rays.10 With it being so easy for the effectiveness of sunscreen to diminish, the only surefire way to maintain protection against sun damage with sunscreen is to regularly replenish and reapply. Remember, using a broad-spectrum sunscreen provides comprehensive protection against both
UVA and UVB rays.

Other Ways to Protect Skin

Protecting your skin, especially from the harmful effects of UV radiation, requires a comprehensive approach that goes beyond just applying sunscreen. Here are several additional methods to safeguard your skin, particularly when indoors or during minimal sun exposure:
  • UV-Blocking Fabrics: Wear clothing made from fabrics that offer UV protection. Look for items with a UPF (Ultraviolet Protection Factor) rating. You may also choose to install curtains with a UPF to further reduce your exposure to UV rays.
  • UV-Filtering Window Films:
    Install films on your home or car windows that block UVA and UVB rays. This can significantly reduce the amount of UV radiation entering indoors.11
  • Screen Filters:
    Use HEV light or blue light screen filters on computers, smartphones, and tablets to reduce blue light exposure, in turn reducing free radicals.8
  • Avoid Peak Sun Hours: Limit exposure to direct sunlight, especially during peak UV radiation hours, typically between 10 a.m. and 4 p.m.
  • Antioxidant-Rich Foods: Consume a diet rich in antioxidants, which can help combat skin damage caused by free radicals
    .12 This includes fruits, vegetables, nuts, and green tea.
  • Moisturize:
    You can use natural oils such as sesame, coconut, peanut, olive, or cottonseed to boost your skin’s resistance to UV rays.13
  • Avoid Chemical Exfoliants:
    Alpha hydroxy acids (AHAs) such as glycolic acid, lactic acid, and tartaric acid, can increase UV sensitivity and hyperpigmentation from the sun.14
  • Topical Antioxidants: Products containing antioxidants like vitamin C, vitamin E, and ferulic acid can provide additional protection against free radicals from environmental damage
    .15
Indoor sun protection is not just a precaution but a necessary step in maintaining long-term skin health. Whether you're at home, in a car, or flying, protecting your skin from UV radiation is crucial. Additionally, if you ever find yourself with a burn, it's important to know how to effectively treat a sunburn for soothing relief and faster healing.

Other Ways to Protect Skin

Protecting your skin, especially from the harmful effects of UV radiation, requires a comprehensive approach that goes beyond just applying sunscreen. Here are several additional methods to safeguard your skin, particularly when indoors or during minimal sun exposure:
  • UV-Blocking Fabrics: Wear clothing made from fabrics that offer UV protection. Look for items with a UPF (Ultraviolet Protection Factor) rating. You may also choose to install curtains with a UPF to further reduce your exposure to UV rays.
  • UV-Filtering Window Films:
    Install films on your home or car windows that block UVA and UVB rays. This can significantly reduce the amount of UV radiation entering indoors.11
  • Screen Filters:
    Use HEV light or blue light screen filters on computers, smartphones, and tablets to reduce blue light exposure, in turn reducing free radicals.8
  • Avoid Peak Sun Hours: Limit exposure to direct sunlight, especially during peak UV radiation hours, typically between 10 a.m. and 4 p.m.
  • Antioxidant-Rich Foods: Consume a diet rich in antioxidants, which can help combat skin damage caused by free radicals
    .12 This includes fruits, vegetables, nuts, and green tea.
  • Moisturize:
    You can use natural oils such as sesame, coconut, peanut, olive, or cottonseed to boost your skin’s resistance to UV rays.13
  • Avoid Chemical Exfoliants:
    Alpha hydroxy acids (AHAs) such as glycolic acid, lactic acid, and tartaric acid, can increase UV sensitivity and hyperpigmentation from the sun.14
  • Topical Antioxidants: Products containing antioxidants like vitamin C, vitamin E, and ferulic acid can provide additional protection against free radicals from environmental damage
    .15
Indoor sun protection is not just a precaution but a necessary step in maintaining long-term skin health. Whether you're at home, in a car, or flying, protecting your skin from UV radiation is crucial. Additionally, if you ever find yourself with a burn, it's important to know how to effectively treat a sunburn for soothing relief and faster healing.
Key Takeaways:
  • Necessity of Indoor Sun Protection: Sunscreen, like OS-01 SHIELD and OS-01 BODY SPF (coming soon), is essential for skin health due to the UV radiation that causes up to 90% of extrinsic skin damage.
  • UVA Rays Indoors: Harmful rays can penetrate glass, contributing to skin aging and cancer, with 60% penetrating windows and causing significant exposure indoors.
  • Benefits of Indoor Sunscreen Use: Protects against UVA rays, preventing collagen and elastin breakdown, reducing skin aging signs, and decreasing skin cancer risks. It also blocks HEV light from screens, preventing premature aging and hyperpigmentation.
  • Sunscreen Reapplication Indoors: Essential every four to six hours, especially near windows. Frequency depends on individual factors and SPF level.
  • Additional Skin Protection Methods: Wearing UV-blocking fabrics, using UV-filtering window films, applying screen filters for HEV light, limiting sun exposure during peak hours, consuming antioxidant-rich foods, moisturizing with natural oils, avoiding chemical exfoliants, and using topical antioxidants.
Key Takeaways:
  • Necessity of Indoor Sun Protection: Sunscreen, like OS-01 SHIELD and OS-01 BODY SPF (coming soon), is essential for skin health due to the UV radiation that causes up to 90% of extrinsic skin damage.
  • UVA Rays Indoors: Harmful rays can penetrate glass, contributing to skin aging and cancer, with 60% penetrating windows and causing significant exposure indoors.
  • Benefits of Indoor Sunscreen Use: Protects against UVA rays, preventing collagen and elastin breakdown, reducing skin aging signs, and decreasing skin cancer risks. It also blocks HEV light from screens, preventing premature aging and hyperpigmentation.
  • Sunscreen Reapplication Indoors: Essential every four to six hours, especially near windows. Frequency depends on individual factors and SPF level.
  • Additional Skin Protection Methods: Wearing UV-blocking fabrics, using UV-filtering window films, applying screen filters for HEV light, limiting sun exposure during peak hours, consuming antioxidant-rich foods, moisturizing with natural oils, avoiding chemical exfoliants, and using topical antioxidants.
By Felix Tajanko: Felix is studying Bioengineering at the University of California - San Diego and is passionate about scientific writing as well as the research of menopausal endocrinology and microhemodynamics.
By Felix Tajanko: Felix is studying Bioengineering at the University of California - San Diego and is passionate about scientific writing as well as the research of menopausal endocrinology and microhemodynamics.

Reviewed by Alessandra Zonari, PhD, Chief Scientific Officer (CSO) and Co-Founder of OneSkin

Alessandra earned her Master’s degree in stem cell biology, and her PhD in skin regeneration and tissue engineering at the Federal University of Minas Gerais in Brazil in collaboration with the 3B’s Research Group in Portugal. Alessandra did a second post-doctoral at the University of Coimbra in Portugal. She is a co-inventor of three patents and has published 20 peer-reviewed papers in scientific journals.

Reviewed by Alessandra Zonari, PhD, Chief Scientific Officer (CSO) and Co-Founder of OneSkin

Alessandra earned her Master’s degree in stem cell biology, and her PhD in skin regeneration and tissue engineering at the Federal University of Minas Gerais in Brazil in collaboration with the 3B’s Research Group in Portugal. Alessandra did a second post-doctoral at the University of Coimbra in Portugal. She is a co-inventor of three patents and has published 20 peer-reviewed papers in scientific journals.

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