The airborne microbiological ecology of enclosed spaces

A quantitative and qualitative analysis of the airborne microbial ecology was performed in two buildings on the National Institutes of Health campus during the spring and summer, 1984. Both buildings had energy conservation design features such as sealed windows, carpeted floors, and mechanical ventilation systems. The Lister Hill Center (LHC) represented an office environment and the Ambulatory Care Research Facility (ACRF) represented a laboratory environment. Two microbial air samplers, the all-glass impinger (AGI) and Andersen sampler, were used in this study.; In the LHC, the airborne concentration using the AGI, measured as colonies/m{dollar}sp3{dollar} air (C/m{dollar}sp3{dollar}), ranged from 2-12 C/m{dollar}sp3{dollar} in spring and 1-165 C/m{dollar}sp3{dollar} in summer. The airborne concentration using the Andersen sampler, measured as colony forming units/m{dollar}sp3{dollar} air (CFU/m{dollar}sp3{dollar}) ranged from 17-130 CFU/m{dollar}sp3{dollar} indoors and 45-169 CFU/m{dollar}sp3{dollar} outdoors during spring, and from 23-74 CFU/m{dollar}sp3{dollar} indoors and 196-411 CFU/m{dollar}sp3{dollar} outdoors during summer. In a seasonal comparison, the concentration of airborne microorganisms indoors, as C/m{dollar}sp3{dollar}, was higher during the summer than spring.; In the ACRF, the airborne concentration using the AGI ranged from 0-43 C/m{dollar}sp3{dollar} in spring and 1-91 C/m{dollar}sp3{dollar} in summer. The airborne concentration using the Andersen sampler ranged from 34-58 CFU/m{dollar}sp3{dollar} indoors to 103-236 CFU/m{dollar}sp3{dollar} outdoors during spring and 19-95 CFU/m{dollar}sp3{dollar} indoors to 241-449 CFU/m{dollar}sp3{dollar} outdoors during summer. In a seasonal comparison, the concentration of airborne microorganisms indoors, as CFU/m{dollar}sp3{dollar}, was higher in the summer sampling period than the spring.; Gram positive organisms accounted for 63% of all isolated indoors, and 28% outdoors. The most common isolates in both buildings were species of Micrococcus and Staphylococcus indoors and Bacillus and Streptomyces outdoors.; There were 30 mold genera identified which represented 37% of the total organisms isolated. In the LHC, molds accounted for 34% of the isolates indoors and 66% outdoors. In the ACRF, molds accounted for 10% of the isolates indoors during the spring and 28% in summer. The most common mold isolates were species of Aspergillus, Penicillium, Cladosporium, Cospora, and Fusarium.; The gram negative organisms represented 2% of the total isolates identified and yeast represents 9%.