A porous material on which solid particles present in air or other fluid which flows through it are largely caught and retained. Filters are made with a variety of materials: cellulose and derivatives, glass fibre, @[email protected], synthetic plastics and fibres. Filters may be naturally porous or be made so by mechanical or other means. @[email protected]/@[email protected] filters are prepared with highly controlled pore size in a sheet of suitable material such as polyfluoroethylene, polycarbonate or cellulose @[email protected] Nylon mesh is sometimes used for reinforcement. The pores constitute 80–85% of the filter volume commonly and several pore sizes are available for air sampling (\(0.45-0.8\ \unicode[Times]{x3BC}\text{m}\) are commonly employed).
PAC, 1990, 62, 2167. (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2188 [Terms] [Paper]