Application of Culturable Sampling Methods for the Assessment of Workplace Concentrations of Bioaerosols

Abstract

Case studies are presented demonstrating the utility of culturable air sampling methods as exposure assessment tools. These investigations included (1) plants that manufacture enzymes, (2) a paper mill, and (3) a large office building with a ventilation system contaminated with Penicillium. In the first case study, a comparison of total bacterial counts (in combination with identification and quantification of the production strain) from unit processes to background locations identified exposure sites. Additionally, a comparison of the sampling results across the three manufacturing plants (among similar processes) identified effective control strategies based on the containment capabilities of the various technologies. This evaluative framework was also successfully applied in the second and third case studies. In combination with the identification and quantification of suspect microorganisms, emission patterns were identified to known immunologically active agents. In the second case study, elevated levels of Thermoactinomyces species were documented in the transfer tower and the biomass storage building. In the third case study, Penicillium from a contaminated ventilation system was identified as the predominant fungus in the indoor air. Current sampling methodologies for microbiological agents in ambient air are limited in their ability to comprehensively characterize personal exposures. However, these air sampling methods provide information that can be used to propose theories concerning agent dissemination and effectiveness of exposure control methods. In addition, when combined with medical and epidemiologic evidence, the collected data can help to establish causal relationships between exposures and symptoms