Bioaerosol

About: Bioaerosol is a research topic. Over the lifetime, 1347 publications have been published within this topic receiving 34791 citations.

The Effect of Phosphate Buffer on Aerosol Size Distribution of Nebulized Bacillus subtilis and Pseudomonas fluorescens Bacteria

Abstract: During bioaerosol research microorganisms are frequently aerosolized from phosphate-buffered suspension via air-jet nebulization. Buffer will therefore be present in organism-free droplets (''empties") as solutes in hydrous surface coatings of airborne organisms or as dry surface coatings on organisms. It might be expected that the buffer would influence the resulting aerosol size distribution and that the influence might vary with relative humidity. In this work we examined the effect of various buffer concentrations on the aerosol size distribution of Bacillus subtilis (B. subtilis) and Pseudomonas fluorescens ( P. fluorescens ) at various relative humidities. Microorganism suspensions in distilled deionized water and phosphate-buffered water were prepared and nebulized from a 3-jet Collison nebulizer into a sampling chamber maintained at 10% relative humidity. The aerosol was then conducted to a second chamber to which moist air was added to achieve the target relative humidity. Particle aerodynamic si...

Bioaerosol Concentrations and Size Distributions during the Autumn and Winter Seasons in an Industrial City of Central China

Abstract: The ambient bioaerosols were measured in PM2.5 and PM10 samples taken in Huangshi City, Hubei Province, China, during autumn and winter from November 2017 to February 2018. Both the bioaerosol number concentration and size distribution (0.37–16 µm) were obtained by direct fluorescent staining coupled with microscopic imaging. The bioaerosol number concentrations ranged from 0.05 to 3.4 # cm–3 for PM2.5 and from 0.17 to 5.7 # cm–3 for PM10, with averages of 0.90 # cm–3 and 1.9 # cm–3, respectively. In terms of particle number, the bioaerosols were dominated by fine particles (0.37–2.5 µm in diameter), with a larger proportion of submicron than supermicron particles. Assuming a unit density of 1 g cm–3 and a spherical shape for the particles, the mass abundances of the bioaerosols were estimated to be 2.4 ± 1.9% and 4.8 ± 3.2% of the PM2.5 and PM10, respectively, as measured by a nearby compliance monitor. Higher bioaerosol concentrations were observed in winter than autumn and on polluted than non-polluted days. During heavily polluted conditions, bioaerosols in the PM2.5 and PM10 were enriched by 6 and 3.7 times, respectively, compared to non-polluted days and contributed up to 15% of the PM10 mass. Rainfall and snowfall appeared to lower the bioaerosol levels. As enhanced emission controls on combustion and dust sources decrease PM levels in China, the bioaerosol fraction in measured PM concentrations will likely increase.

A small change in the design of a slit bioaerosol impactor significantly improves its collection characteristics.

Abstract: While several methods are available for bioaerosol monitoring, impaction remains the most common one, particularly for collecting fungal spores. Earlier studies have shown that the collection efficiency of many conventional single-stage bioaerosol impactors falls below 50% for spores with an aerodynamic diameter between 1.7 and 2.5 μm because their cut-off size is 2.5 μm or greater. The cut-off size reduction is primarily done by substantially increasing the sampling flow rate or decreasing the impaction jet size, W, to a fraction of a millimetre, with both measures often impractical to implement. Some success has recently been reported on the utilization of an ultra-low jet-to-plate distance, S (S/W < 0.1), in circular impactors. This paper describes a laboratory evaluation and some field testing of two single-stage, single-nozzle, slit bioaerosol impactors, Allergenco-D and Air-O-Cell, which feature the same jet dimensions and flow rate but have some design configuration differences that were initially thought to be of low significance. The collection efficiency and the spore deposit characteristics were determined in the laboratory using real-time aerosol spectrometry and different microscopic enumeration methods as the test impactors were challenged with the non-biological polydisperse NaCl aerosol and the aerosolized fungal spores of Cladosporium cladosporioides, Aspergillus versicolor, and Penicillium melinii. The tests showed that a relatively small reduction in the jet-to-plate distance of a single-stage, single-nozzle impactor with a tapered inlet nozzle, combined with adding a straight section of sufficient length, can significantly decrease the cut-off size to the level that is sufficient to efficiently collect spores of all fungal species. Furthermore, it appears that the slit jet design may improve the application of partial spore counting methodologies with respect to those applied to circular deposits. Data from a demonstration field study, conducted with the two samplers in environments containing a variety of fungal species, supported the laboratory findings.