In physical sunscreen, nano ZnO and titanium dioxide are used as sunscreens. These particles are treated nano-scale size that can effectively reflect UV light in various wave length(UVA 400 nm–320 nm, UVB 320 nm–280 nm). It is not only safer and milder but provide longer protection against UV-light comparing to the common chemical sunscreen in the market.

Most chemical sunscreen uses ingredients such as oxybenzone to absorbs UV light. This type of sunscreen loses its function when absorption of the chemical ingredient is saturated. Then users have to reapply the sunscreen from time to time when exposured under sunshine all day long in summer time. Moreover, some of these chemical ingredients, suspected as  photocarcinogen, might penetrate human skin.