Comparison of Single and Multiple Stage Sieve Samplers for Airborne Microorganisms ^{1, 3}

Single and multiple stage air samplers were evaluated under commercial conditions for enumerating airborne microbial particles in a plant in which swine were slaughtered and pork was further processed. Three volumes of air, 0.014, 0.028, (1 ft³), and 0.057 cu M were sampled in duplicate on each of 2 days (for airborne molds, yeasts, coliforms, and aerobic bacteria) in eight rooms where pork carcasses were handled and further processed. Unexpectedly, the microbial counts were low during this winter sampling. The single and multiple samplers yielded mean (log₁₀) counts (n = 94) of 0.15 and 0.42; -0.23 and -0.36; 1.18 and 1.29; and -0.63 and -0.91 per 0.028 cm M; for molds, yeasts, aerobes and coliforms, respectively. The multiple sampler detected slightly greater numbers of molds and aerobic bacteria, but did not define the differences in aerobic bacterial numbers from among the various processing rooms as readily as the single stage sampler. Counts of coliforms were higher from the single than from the multiple stage sampler. The single stage sampler required only one petri dish per sample, as compared with six for the multiple stage sampler, so it required less medium and time for evaluating air for microorganisms.