Particle inertia determines whether airflow can redirect the particle around a nozzle. As airflow accelerates through progressively smaller nozzles, particles with sufficient inertia cannot follow the changing air path and impact a collection surface. Particles with less inertia remain suspended and continue downstream, allowing the instrument to separate the aerosol according to aerodynamic diameter.
The staged design creates successive aerodynamic separation points rather than one broad collection step. Larger aerodynamic particles are removed earlier, while smaller particles pass to later stages as the nozzle dimensions decrease. Comparing material collected across the stages reveals the particle-size distribution and provides a basis for estimating which respiratory regions particles may reach.
The distribution of material across collection surfaces indicates how the aerosol is partitioned among aerodynamic size ranges. A concentration concentrated on earlier stages suggests a greater contribution from particles with higher inertia, whereas later-stage collection indicates smaller airborne particles. This stage-by-stage pattern supports interpretation of potential respiratory deposition and exposure.
Researchers direct the aerosol through the impactor, allowing the airflow to accelerate through each successive stage. Particles are retained on the appropriate collection surfaces when their inertia prevents them from following the airflow. Material associated with the stages is then used to determine the particle-size distribution and relate it to respiratory deposition or exposure.
Infectious bioaerosol studies use the measured aerodynamic size distribution to characterize airborne particles relevant to transmission and exposure. The results help researchers examine how infectious material may be distributed through an aerosol and support assessment of dose-related conditions. They can also inform evaluation of aerosol-generating procedures in immunology and infection research.
Measurements from a Cascade Impactor show how an inhaled therapeutic or respiratory aerosol is distributed by aerodynamic diameter. That information helps researchers predict where particles may deposit in the respiratory tract and assess whether an intervention produces a relevant airborne profile. These data support improvement of inhalation-based interventions and interpretation of their potential airway delivery.