Air sampling products are used to capture a sample for later testing, or to test the air directly with meters that include internal sensors. Gas sampling bags, made of PVDF, FEP, or Tedlar®, are used to capture an air sample that can be tested later. Air sampling pumps draw a test sample into a bag or cartridge to test employee exposure levels over a period of time. Reuter Centrifugal Impaction (RCS) microbial air samplers have been used by the pharmaceutical industry for years to draw airborne microorganisms onto an agar media strip for analysis. Dust monitors can be used as part of an indoor air quality/industrial hygiene audit to measure concentration levels of dust in the environment.