TOTOBOBO® mask contains BioCote®, a silver based anti-microbial agent. The silver ion ingredient provides continuous antiÂ*microbial properties through out the life time of the product. BioCoteÂ® effectively inhibits the function, growth and reproduction of a wide range of micro-organisms. Silver ion based antimicrobial additives have been proven to work throughout history. It is not toxic, flammable nor corrosive and will not cause bacteria to become resistant to antibiotics.BioCote® active ingredients are registered with the US Environmental Protection Agency (EPA).