Anti-microbial filter

A foam filter for filtering air comprising an open-celled phenolic foam, the open-celled phenolic foam having an accessible pore volume of from 0.5 m3 to 0.96 m3 per m3 of foam, the open-celled phenolic foam comprising cells having an average cell size of from 0.5 mm to 7 mm;

• and the phenolic open-celled foam further comprising an antimicrobial agent, wherein the open-celled phenolic foam has a density of from 80 kg/m3 to 800 kg/m3.