Whatman EPM 2000 Glass Microfiber Filters have been developed and produced especially for use in high volume PM-10 air sampling equipment that collects atmospheric particulates and aerosols. It is manufactured from 100% pure borosilicate glass of special purity enabling detailed chemical analysis of trace pollutants to take place with the minimum of interference or background. EPM 2000 filters are available in either a 4.7cm circle filter or an 8 x 10 in. sheet. Both sizes come 100/Box. Whatman EPM 2000 was selected by the EPA to be the standard filter for use in the nationwide network of HiVol air samplers. Sheets are individually numbered to facilitate identification.