The best SPF for sunscreen generally recommended by experts is at least SPF 30. This level blocks about 97% of UVB rays, which are primarily responsible for sunburn and contribute to skin cancer
. For extended outdoor activities or for people at higher risk of skin damage (such as those with a history of skin cancer, genetic conditions, or when exposed to intense sun like at high altitudes or near the equator), an SPF of 50 or higher is advised. SPF 50 blocks approximately 98% of UVB rays, providing slightly more protection than SPF 30, but the difference is relatively small
. SPF values above 50 (like SPF 70 or SPF 100) offer only marginally better UVB protection (about 99% at SPF 100), and may create a false sense of security, leading to longer sun exposure without reapplication, which can increase risk
. Key points for effective sun protection include:
- Use a broad-spectrum sunscreen that protects against both UVA and UVB rays.
- Apply sunscreen generously about 15-30 minutes before sun exposure.
- Reapply every two hours, or immediately after swimming or sweating.
- Choose water-resistant formulas if you expect to be active or in water
In summary, for most people, a broad-spectrum sunscreen with SPF 30 to 50 is optimal, balancing effective protection without misleading overconfidence. Higher SPFs provide slightly more protection but require proper application and frequent reapplication to be effective
