Measure concentration and paricle size distribution of aerobic bacteria and fungi in ambient air with the Thermo Scientific™ Six-Stage Viable Andersen Cascade Impactor. This multi-orifice sampler is widely used as a standard for enumerating the viable particles in a microbial aerosol. - See more at: http://www.thermoscientific.com/content/tfs/en/product/six-stage-viable-andersen-cascade-impactor-1.html#sthash.G8drHRXn.dpuf