A technique for collecting airborne particulate in which the sampling device has a
collection efficiency of unity for all sizes of particles in sampled air, regardless of wind
velocity and direction of the instrument. The air stream entering the collector has
a velocity (speed and direction) equal to that of the air in the gas stream just ahead
of the sampling port of the collector.
Source:
PAC, 1990, 62, 2167
(Glossary of atmospheric chemistry terms (Recommendations 1990))
on page 2198