Check out this answer from Consensus:
Based on the reviewed studies, it appears that sunscreen use can lead to longer durations of sun exposure, particularly when the exposure is intentional. However, for short, non-intentional exposures, such as being in the sun for up to 20 minutes a day, the risk of significant UV damage is relatively low. It is generally safe to be in the sun without sunscreen for brief periods, but individuals should be mindful of their skin type, the time of day, and the intensity of the sun. For extended sun exposure, using sunscreen and other protective measures is advisable to minimize the risk of skin damage and skin cancer.
Exposure to sunlight is essential for the synthesis of vitamin D, which is crucial for bone health and overall well-being. However, prolonged exposure to ultraviolet (UV) radiation from the sun can lead to skin damage, sunburn, and an increased risk of skin cancers such as melanoma. This article explores whether it is safe to be in the sun without sunscreen for up to 20 minutes a day, based on findings from recent research studies.
Sunscreen Use and Sun Exposure Duration
Several studies have investigated the relationship between sunscreen use and the duration of sun exposure. A randomized trial found that the use of sunscreens with different sun protection factors (SPF) could extend the duration of intentional sun exposure. Participants using SPF 30 sunscreen spent more time sunbathing compared to those using SPF 10 sunscreen, with a median daily sunbathing duration of 3.0 hours versus 2.4 hours, respectively1. Another study confirmed that higher SPF sunscreen use was associated with longer recreational sun exposure among young Europeans2.
Intentional vs. Non-Intentional Sun Exposure
The motivation behind sun exposure plays a significant role in determining the duration of time spent in the sun. A systematic review highlighted that sunscreen use leads to longer sun exposure durations when the exposure is intentional, such as sunbathing or tanning. In contrast, when sun exposure is non-intentional, sunscreen use does not significantly increase the time spent in the sun3.
Risk of Sunburn and Skin Cancer
While sunscreens are effective in preventing sunburns by blocking UV radiation, their use may paradoxically increase the risk of skin cancer due to prolonged sun exposure. Studies have shown that individuals using higher SPF sunscreens tend to stay in the sun longer, potentially increasing their cumulative UV exposure and the associated risk of cutaneous melanoma1 2 3.