Showing papers on "Bioaerosol published in 1994"

Impaction onto a Glass Slide or Agar versus Impingement into a Liquid for the Collection and Recovery of Airborne Microorganisms.

Abstract: To study impaction versus impingement for the collection and recovery of viable airborne microorganisms, three new bioaerosol samplers have been designed and built. They differ from each other by the medium onto which the bioaerosol particles are collected (glass, agar, and liquid) but have the same inlet and collection geometries and the same sampling flow rate. The bioaerosol concentrations recorded by three different collection techniques have been compared with each other: impaction onto a glass slide, impaction onto an agar medium, and impingement into a liquid. It was found that the particle collection efficiency of agar slide impaction depends on the concentration of agar in the collection medium and on the sampling time, when samples are collected on a nonmoving agar slide. Impingement into a liquid showed anomalous behavior with respect to the sampling flow rate. Optimal sampling conditions in which all three new samplers exhibit the same overall sampling efficiency for nonbiological particles have been established. Inlet and collection efficiencies of about 100% have been achieved for all three devices at a sampling flow rate of 10 liters/min. The new agar slide impactor and the new impinger were then used to study the biological factors affecting the overall sampling efficiency. Laboratory experiments on the total recovery of a typical environmental microorganism, Pseudomonas fluorescens ATCC 13525, showed that both sampling methods, impaction and impingement, provided essentially the same total recovery when relatively nonstressed microorganisms were sampled under optimal sampling conditions. Comparison tests of the newly developed bioaerosol samplers with those commercially available showed that the incorporation of our research findings into the design of the new samplers yields better performance data than data from currently available samplers.

Variations in airborne pollen antigenic particles caused by meteorologic factors.

Abstract: High birch pollen antigenic activities in outdoor air samples were found in all particle sizes studied (> 7.2, 2.4-7.2, < 2.4 microns and molecular size class, with an ELISA modification). Sampling was done with a low-volume, size-selective bioaerosol sampler (SSBAS) simulating the human respiratory tract in both volume and fractionation. Airborne birch pollen counts for comparisons were obtained from a Burkard trap. No correlations were obtained between antigen concentrations in any particle size fraction and airborne pollen counts. The meteorologic factors studied differed clearly in their effect on antigenicity, depending on the size class studied. Likewise, the effect of meteorologic factors differed among the three study periods (period I, 4 weeks before the peak pollen season; period II, during the season; and period III, 4 weeks after the season). During the peak pollen period, temperature and relative humidity were the most important meteorologic factors. Before the season, large and very small particles predominated, medium-sized particles being totally absent. The largest size class studied (containing all intact pollen grains) clearly reacted to changes in meteorologic factors; for smaller size classes, these factors were found to be less important, a fact which may make the forecasting of antigen concentrations in the air on the basis of meteorologic data impossible.

Distribution of Microbial Bioaerosol

Abstract: Although the atmosphere forms a continuous bioaerosol transport medium between indoor and outdoor air, barriers occur that hinder airflow. Because of these hinderances, it has been assumed that it is adequate to study these two environments separately. As more is learned about both populations, this assumption may need to be changed.

Instrumentation Used with Microbial Bioaerosols

Abstract: Bioaerosol monitoring is a rapidly emerging area of industrial hygiene that is finding increased use and overuse. It is often used in conjunction with indoor environment quality investigations, infectious disease outbreaks, and agricultural health investigations. Bioaerosol monitoring includes the measurement of viable (culturable and nonculturable) and nonviable microorganisms in both indoor (e.g., industrial, office, or residential) and outdoor (agricultural and general air quality) environments. In general, indoor bioaerosol sampling need not be performed if visible growth is observed. Contamination (microbial growth on floors, walls, or ceilings, or in the HVAC system) should be remediated. If personnel remain symptomatic after remediation, air sampling may be appropriate, keeping in mind that negative results are quite possible and they should be interpreted with caution. Other exceptions for which bioaerosol sampling may be appropriate include epidemiological investigations, research studies, or if indicated after consultation with an occupational physician and an immunologist.

Bioaerosol Sampling in Field Studies: Can Samples be Express Mailed?

Abstract: 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 sample...

Atmospheric Environment of Bioaerosols

Abstract: Bioaerosols are influenced by the atmosphere from the first moment they are exposed to the environment Therefore, knowledge of local weather and climate is an important factor in planning the time and location of aerosol release and for assessing the area and period influenced by bioaerosol dispersal and survival The most important influences of the atmospheric environment on bioaerosols are the dispersion and evaporation of droplets and the survival of organisms contained in the droplets Combined effects of the dispersion, removal, and survival of microorganisms in sprayed droplets determine the area and period affected by sprayed aerosols

Bioaerosol Generation in a Food Processing Plant: A Comparison of Production and Sanitation Operations

Abstract: Elevated bioaerosol levels may be an important concern in the food industry, because depending on the species and numbers involved, bioaerosols can increase the risk for both employees and consumers. Some food processing facilities must maintain production during sanitation with high pressure spraying, which may cause food contamination and expose production workers to bioaerosols. Bioaerosol concentrations were investigated for two operating modes in a food processing industry: production alone versus production with concurrent sanitation of food processing equipment. The sanitation was done using high pressure water washing. Air samples were taken using AGI-30 impingers. Bacteria, mold, and yeast were counted and bacteria and mold were identified. Total bacterial plate counts ranged from 150 to 325 colony forming units (CFUs)/m3 for production alone and from 850 to 2500 CFUs/m3 for production with concurrent sanitation. Bacteria counts were significantly greater during production with concurren...

Dispersion Models of Microbial Bioaerosols

Abstract: Many bioaerosol models have been prepared ranging from compartment models (Forrester, 1961; Atkins, 1969), describing the downwind concentrations and flux (i.e., D/P transfer rate where D/P is a droplet/particle; D/P/M−2 s−1) of bioaerosols from a source that contributes to the loading of the bulk atmosphere (Fig. 9.1) through comprehensive, theoretical, and multiple regression models characterizing the factors that affect the survival of airborne microbes (Larson, 1973) [Eq. (9.1)].