Bioaerosol sampling in field studies: can samples be express mailed?

Bioaerosol sampling for viable microorganisms was conducted in 25 dairy barns in summer and in winter to examine the relationship of sample storage and shipping in determining bioaerosol concentrations separately for yeasts, molds, mesophilic bacteria, and thermophilic organisms. The study also compared the performance of three sampling methods--(1) all-glass impinger (AGI) used with peptone solution in both seasons and (2) betaine solution in winter; and (3) the nuclepore filtration and elution (NFE) method, using air filtration with subsequent elution and culturing--which were studied in a pairwise fashion with duplicate, simultaneous, side-by-side sampling. For each sample, one duplicate was analyzed within two hours in a laboratory less than 50 km from the sampling site, while the other was express-mailed to the authors' laboratory. Concentrations of all microorganisms measured by the AGI peptone method were unaffected by mailing in winter, but mesophilic bacteria increased in summer. AGI betaine samples were unchanged except for increased concentrations of molds after mailing in winter. Yeasts and mesophilic bacteria significantly decreased after mailing of NFE samples. Pairwise comparison of the sampling methods in winter yielded no significant differences in airborne concentrations for the yeasts, mesophilic bacteria, and thermophilic bacteria. Both AGI betaine and NFE methods had significantly greater concentrations of molds than AGI peptone. In summer, concentrations of yeasts and mesophilic bacteria were significantly greater with AGI peptone, as were molds with the NFE method.(ABSTRACT TRUNCATED AT 250 WORDS)