A comparison of two-stage and six-stage Andersen impactors for viable aerosols

Abstract

The widely used Andersen six-stage air sampler for viable aerosols was compared with the more recently available metallic (non-disposable) two-stage sampler at several wastewater and wastewater sludge treatment facilities. Both bacterial indicator organisms and fungi were measured using biological media appropriate for each. The two sampling instruments were mounted on a single tripod and simultaneous side-by-side air samples were collected. These samples were processed in an identical manner and the data was analyzed to yield bacterial and fungal colony forming units per cubic meter of air for each of the sampling devices. In order to determine a baseline of variability between sampling devices in the field, samples were also collected using two six-stage samplers side-by-side and two two-stage samplers side-by-side. This research was undertaken to determine by statistical analysis whether results using the non-disposable two-stage sampler are different from those using the six-stage sampler under field ...