Do we need to apply sunscreen indoors?

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This is a very common yet often overlooked skincare question.

Many people believe sunscreen is only necessary outdoors or under strong sunlight, but in fact, sun protection is not only about preventing sunburn. In the pursuit of holistic wellbeing and beauty, understanding how light affects the skin is an important step in gently caring for it.

Which indoor situation calls for sunscreen?

Whether sunscreen is needed depends on your environment. The following everyday scenarios often affect the skin more than we realise:

1. Working near a window for long periods

Ordinary glass panel can block most UVB rays that cause sunburn, but it offers little protection against UVA, which contributes to skin ageing.

UVA has strong penetrating power and can pass through glass into indoor spaces. Long-term exposure to it can accelerate skin sagging, fine lines, and pigmentation.

2. Staying in spaces with strong natural lighting

Modern offices, cafés, sunrooms, or car interiors may feel comfortable and bright, but they can expose the skin to prolonged “filtered sunlight”.

Under this soft yet continuous light, the impact of UVA on the skin should not be ignored.

3. Prolonged use of computers, mobile phones, and other digital screens

Studies suggest that blue light emitted by electronic screens may worsen pigmentation and increase oxidative stress.

If you spend long hours using digital devices in bright indoor lighting or near windows, sunscreen not only helps block UV rays but also supports the skin against environmental stress.

Which indoor situations may not require sunscreen?

-       Being in a basement or internal room with no windows

-       Staying far from windows and not using electronic devices for extended periods

-       Short indoor stays, with most time spent away from natural light sources

How can you tell if you need sunscreen indoors?

1. A simple check:

During daylight hours, observe whether your usual seating area receives direct or indirect light.

If you can “sit in the light” indoors without feeling sun exposure, that is often within the range of UVA.

You may also refer to the UV Index on your weather app.

When the outdoor UV Index is 3 or above and you are near a window, indoor UVA exposure is worth paying attention to.

2. What type of sunscreen should you choose?

For frequent outdoor exposure, choose sunscreens labelled with PA++ protection. Products containing botanical nutrients and vitamin B3, such as UCARA UV Protection SPF 50++, help prevent skin damage and effectively block UV penetration.

For indoor use, SPF 15–30 is generally sufficient. Higher SPF mainly targets UVB, which is largely reduced by glass indoors. UCARA Sunscreen Cream SPF 25++ is recommended, as it effectively filters glass-refracted UVA and UVB. For indoor use, lighter, non-greasy textures that do not interfere with makeup are easier to maintain consistently.

Summary recommendation:

If you spend extended periods (for example, more than 30 minutes) within 2 metres of a window, or work in a bright environment with ample natural light, it is advisable to include sunscreen as part of your morning skincare routine to build a stable protective barrier for the skin.

If applying sunscreen separately feels inconvenient, you may opt for a day cream or primer containing SPF and PA values as a convenient indoor alternative—but sunscreen application remains essential.

The core purpose of applying sunscreen:

The main purpose of sunscreen is not merely to prevent tanning,

but to prevent photoageing—collagen loss, fine lines, and pigmentation caused by the long-term accumulation of UVA exposure.

This is a gentle, long-term skincare approach that lays the foundation for future skin health.

If you care about the skin’s long-term balance and health, and are exposed to indoor natural light during the day, treating sunscreen as part of your morning skincare routine is a simple and effective anti-ageing habit.