The major objective of the Particulate matter Airborne Sampling INlet experiment (PASIN) project was to determine airborne aerosol inlet losses due to inertial and electrophoretic processes in sampling inlets. It was observed in previous studies that these losses can exceed 50% in some cases. A variety of intake systems aboard NCAR's Electra were sampled simultaneously to establish which parameters (flow Reynolds number, Stokes number, radius of curvature, surface coating, aerosol diameter, etc.) control these losses. All nights were in the boundary layer, half marine and half continental air mass.

Four approaches were used:

1. Direct comparison of the apparent bulk concentrations found on filters located behind six different inlets.
2. ASASP sampling of the aerosol size-distribution, both outside the aircraft and just ahead of the filters, to see how it agrees with the bulk losses in the inlets.
3. Washing the deposited material from one intake to QA/QC the bulk comparison approach.
4. Flight test evaluation of several intake systems used aboard earlier sampling programs, by comparing them with external sampler.

The ultimate goal for this experiment was the development of the most artifact-free sampling system for collecting aerosols from aircraft.