Zinc Oxide with 20 nanometers particles is a physical sun blocking agent that has a broad range of effectiveness, covering UVA and UVB. As a single ingredient, zinc oxide is the broadest range sunscreen on the market. It has a long history of safe use. It is not irritating and compatible with sensitive skin. In fact, zinc oxide is a skin protectant and anti-irritant, and is widely used in treating various forms of dermatitis/skin irritation.