sunblock

Sunblock is a term historically used for products designed to protect the skin from ultraviolet radiation by blocking it physically. Today, most products are marketed as sunscreens, but some mineral-based products are still described as sunblocks.

Physical sunblocks use minerals such as zinc oxide or titanium dioxide to reflect or scatter UV rays, providing broad protection. Chemical sunscreens use organic compounds that absorb UV radiation. Both types aim to reduce UVB exposure; many formulations cover UVA as well.

Apply liberally to all exposed skin 15 to 30 minutes before sun exposure and reapply every two hours, or after swimming, sweating, or towel drying. Use water-resistant products if swimming, and reapply after activities that remove the protective layer.

Mineral sunblocks are generally well tolerated and may be preferred for sensitive skin. Some chemical filters can cause irritation or an allergic reaction in some people. Some ingredients have raised environmental concerns; certain jurisdictions regulate labeling and ban specific chemicals in reef-safe products.

In many countries, products labeled broad-spectrum protect against UVA and UVB; SPF indicates UVB protection relative to unprotected skin. Infants under six months should be kept out of direct sun; protective clothing and shade are recommended. Store in a cool, dry place.