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Should you apply sunscreen when you’re in the shade?

We think shade shields us from the sun’s harmful effects, which leads us to skip sunscreen. But is that impression justified? Should we protect our skin in the shade? Let us explore these questions.

Summary

Sunscreen: a product to apply only in sunlight?
Sources

Published June 30, 2025, updated on June 30, 2025, by Pauline, Chemical Engineer — 4 min read

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Sun protection

Sunscreen: a product to apply only in sunlight?

Shade is seen as a refuge from the sun’s hazards. By reducing light intensity, it lowers perceived heat and gives a misleading sense of coolness. In reality, shade does not mean the absence of ultraviolet radiation. Indeed, UV rays can reach the skin by reflection or atmospheric scattering, even when the sun is not shining directly on us. Light surfaces such as sand, snow, or water have significant reflective capacity. This means someone sitting in shade on a beach can receive a significant amount of ultraviolet radiation, even if they are not directly exposed.

Surface	UV reflectance index
Snow	80%
Sand	… 15%
Grass
Water
Concrete

UV reflectance index by surface.

Source: Linos E. et al. Shade types offer varying levels of protection, similar to sunscreens. JAMA Dermatology (2017).

This explains why some people notice they have tanned even though they stayed in the shade.

The clouds do not constitute a reliable barrier either. Average cloud cover allows between 30 and 70% of UV rays, while scattered white clouds can increase total radiation via scattering phenomena, with increases of up to 10%. Only dense, dark, low clouds can block most UV.

A study conducted in Sacramento, California, using UV sensors placed at various points quantified the radiation received in two shaded settings. Scientists examined UV levels under a parasol and beneath a tree to reflect everyday situations. UV sensors were placed in direct sunlight and in these two shaded areas between 1 pm and 3 pm.

Configuration expérimentale globale, montrant les capteurs UV sous le soleil ou à l’ombre d'un arbre ou d'un parasol.

Overall experimental configuration showing UV sensors in direct sunlight or in the shade of a tree or parasol.

Source: SIVAMANI R. K. et al. Quantification of ultraviolet (UV) radiation in the shade and in direct sunlight. Dermatology Online Journal (2019).

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Measurements showed that under a tree about 5% of UV radiation still reached the skin, while under a parasol more than 17% reached the shaded area.

These data show that not all shaded areas are equal in terms of photoprotection. A dense shade, such as that cast by a wall or a roof, blocks a large portion of direct UV rays. In contrast, shade filtered by a leafy tree, a parasol or an open pergola allows a fraction of sunlight through. If we consider that UV rays can reflect off certain surfaces to reach the skin, we recognise that being in the shade does not guarantee complete protection. At different times of day, shaded areas do not offer the same photoprotection.