Skin cancer is the most common cancer in the US, and rates of melanoma reached a record high in the UK in 2023. Despite the abundance of sunscreen products, many people are not applying them correctly, experts warn.
SPF, or sun protection factor, measures how well sunscreen protects skin from UVB rays, which can cause sunburn and skin cancer. According to dermatologists, SPF 15 blocks 93% of UVB radiation, SPF 30 blocks 97%, SPF 50 blocks 98%, and SPF 100 blocks 99%. Both the American Academy of Dermatology and the UK's National Health Service recommend using at least SPF 30.
However, real-world protection depends on factors such as time of day, geographic location, skin type, and application habits. Many people use too little sunscreen, reducing its effectiveness. Using a higher SPF can compensate for under-application, says Dr Heather Rogers, a board-certified dermatologist.
To protect against both UVB and UVA rays—which cause premature ageing and skin damage—experts advise using a broad-spectrum sunscreen. The choice between chemical and mineral sunscreens is a matter of personal preference, but proper application and reapplication are crucial for safety.
