Microorganisms of the upper atmosphere. I. Instrumentation for isokinetic air sampling at altitude.

An aircraft-mounted air-sampling system for the collection of microorganisms from the upper air is described. The system is highly suitable for use in upper air sampling from an aircraft because (i) it is an isokinetic system, (ii) it is simple to operate, (iii) it employs a dry filter, (iv) the volume sampled can be easily determined, and (v) it operates efficiently at all altitudes and ambient temperatures.