Measurement and characteristics of biological aerosols in dairy processing plant environments

All Glass Impinger-30 (AGI-30), Andersen 6-stage Sieve Sampler (Andersen impactor), Reuter centrifugal sampler (RCS) and Millipore membrane filter sampler (Filter sampler) were evaluated for recovery of artificially-generated aerosols and viable particles in dairy processing plant environments. Size distribution of the aerosol was analyzed to determine its relationship to air sampler efficiency. Mean recovery of non-sporeforming bacterial aerosols decreased in the order of Andersen impactor, AGI-30 and Filter sampler, and RCS. The Filter and Andersen samplers recovered greater numbers than other samplers from aerosol of bacterial endospore. Mean viable particle recovery from dairy processing plant air decreased in the order of AGI-30, Andersen impactor, RCS, and Filter sampler, which contrast to those obtained using laboratory-generated aerosols. The increased aerosol recovery by AGI-30 in processing plant compared to laboratory-generated aerosols indicates the presence of "carrier-type" particles which disintegrate upon impingement. The Andersen impactor proved to be the most reliable sampler for recovering biological aerosols from dairy processing plants.;Inoculated Serratia marcescens were detected in the air during drain flooding and after rinsing the floor. These illustrate the ability of microorganisms to be disseminated from drains and wet surfaces via physical disruption activities often observed in food plants. Once a high concentration of wet viable aerosol was generated, it took 40 or more min to return to the background level in the absence of forced ventilation or other activity. The estimated mean aerosol particle sizes from dairy processing plants were from 4.2 to 5.5 ;The performance of RCS was compared with that of Andersen impactor to determine if the RCS is suitable for monitoring airborne microorganisms in dairy processing plants. The RCS recovered most bacterial types since these types were distributed over various particle sizes. When airborne fungi were collected, the RCS collected lower amounts than that of Andersen impactor. The RCS is suitable for use when approximate concentration of non-mold airborne particles, or relative degree of air cleanliness information is needed. Results published in J. Food Prot. and J. Dairy Sci.