Performance of the surface air system air samplers.

Two models of the surface air system (SAS) air sampler have been compared with the Bourdillon slit sampler. These tests show that the effective sampling volume remains nearly constant with an efficiency approximating to 100% over the range of particle sizes likely to be encountered in environmental sampling. At particle sizes below 4 micron the collection efficiency falls off and with 2 micron particles the efficiency is reduced to 50%. The high air flows, c.200 1 min-1 of the samplers are particularly suited to measurements of low levels of airborne micro-organisms.