Andersen Six-stage Sampler

Air enters a sequence of six stages, each progressively finer than the previous one. At every stage, particles whose inertia is sufficient for the local impact conditions deposit on culture media or another collection surface, while smaller particles remain in the air stream and proceed onward. This sequential separation produces a stage-by-stage aerosol size distribution.

Aerodynamic size matters because stage capture depends on how particles behave in the moving air stream, not simply on their presence in the sample. Particles that retain enough inertia to strike a surface are recorded earlier, whereas those that continue with the airflow are recorded later. This makes the stage pattern useful for distinguishing coarser and finer aerosol fractions.

The distribution across stages provides an indication of potential airway travel depth. Particles collected at progressively finer stages represent smaller aerodynamic fractions, which can travel farther into airways than larger fractions. Researchers therefore use the pattern to relate environmental aerosol measurements to possible inhalation-relevant behavior and to identify which particle ranges deserve closer attention.

Using culture media rather than only a generic collection surface can support assessment of airborne microorganisms captured at individual stages. Because each stage represents a different aerodynamic fraction, the resulting observations can show not only whether bioaerosols are present, but also how their distribution changes from larger to finer particle ranges.

The core workflow is to pass a controlled air stream through all six stages, allow particles to impact on the designated culture media or collection surfaces, and then examine the material retained at each stage. Keeping the stage sequence intact is essential because the collection location supplies the information needed to interpret the aerosol size distribution.

Environmental researchers can use stage-specific results to investigate whether filtration, ventilation, or exposure-control measures alter the airborne particle profile. The sampler shows which aerodynamic fractions remain after air passes through an environment or control strategy, providing more detailed information than a single undifferentiated particle measurement.

Because the sampler separates particles by aerodynamic size, it can be used across several environmental aerosol categories, including airborne microorganisms, dust, and other particulate contaminants. The same stage-resolved approach supports comparison of particle profiles among air-quality investigations, contamination assessments, and studies of filtration or ventilation performance.