Showing papers on "Bioaerosol published in 2000"

Performance of Air-O-Cell, Burkard, and Button Samplers for total enumeration of airborne spores.

Abstract: Performance of three devices used for the total enumeration of airborne spores—the Air-O-Cell sampling cassette, the Burkard personal volumetric air sampler, and the Button Aerosol Sampler—was evaluated under controlled laboratory conditions. The first two are glass-slide impactors; the third collects spores on a filter. The samplers were challenged with 0.44–5.10 µm polystyrene latex particles and five microorganisms of 0.84–3.07 µm mean aerodynamic diameter: Streptomyces albus, Bacillus subtilis, Cladosporium cladosporioides, Penicillium brevicompactum, and Penicillium melinii. An optical particle counter measured the particle concentrations upstream and downstream of each sampler, and thus determined the physical collection efficiency of the three samplers. Collection efficiency of the Button Aerosol Sampler was close to 100% for the entire particle size range studied. The cut-off size of each impactor was 2.3–2.4 µm. Acridine orange (with epifluorescent microscopy) and lactophenol cotton blue (with br...

Bioaerosol transport modeling and risk assessment in relation to biosolid placement.

Abstract: A field study was performed in which bioaerosols were sampled at a field site undergoing land placement of anaerobically digested, de-watered biosolid material. The data from these field studies were then used to generate microbial release rates from the biosolids for use in modeling bioaerosol transport. Continuous-point sources represented by large biosolid piles (temporary storage before placement) in the field, and continuous-area sources represented by large fields upon which biosolids were placed by spraying, were modeled using microbial transport models; and downwind microbial concentrations were generated. These quantified transport data were then entered into microbial dose-response models in an attempt to characterize the risk of pathogenic bacteria and viruses infecting workers and nearby population centers. The risk of viral and bacterial infection to workers at biosolid land application sites is 3:100 and 2:100, respectively, under 2-m/s wind conditions and 1 hr of exposure. The route of exposure proposed in this modelis the transport, inhalation, deposition, and swallowing of bacterial or viral pathogens. Note that these risk models by nature would tend to overestimate the actual risk to populations (wastewater workers) consisting primarily of immunocompetent individuals. Under these low-wind conditions, nearby population centers where such immunocompetent populations may exist (here considered to be 10000 m from the land application sites) are predicted to be at little risk (1.95 x 10 -2 :100) of infection from aerosolized bacteria and at no risk from aerosolized viruses.

Assessment of particulates and bioaerosols in eastern Canadian sawmills.

Abstract: The purpose of this study was to quantify and identify the airborne contamination in eastern Canadian sawmills. Seventeen sawmills were chosen to cover a wide range of size, geographic distribution, and wood species processed. Within each sawmill different work sites (debarking, sawing, sorting, or planing) were studied separately. Area sampling was performed for exposure assessment. Microbial contaminants were assessed with all-glass impingers 30 and six-stage Andersen microbial samplers; appropriate selective media and culture conditions for bacteria, thermophilic actinomycetes, molds, and yeasts were used. Inhalable dust, endotoxins, temperature, and humidity also were measured. Penicillium species were the most predominant molds with up to 40 different Penicillium species identified. Debarking was the working site most highly contaminated by molds, bacteria, and endotoxins (p=0.0001). At this working site mold levels reached a maximum of 1.5×106 CFU/m3, whereas the median values for culturable bacteri...

Bacterial aerosol emission from wastewater treatment plants:Culture methods and bio-molecular tools

Abstract: In this report we describe the results of a studyconducted in order to better estimate airbornemicroorganisms. A method based on a bio-moleculartechnique, Polymerase Chain Reaction (PCR) wascompared with the culture methods based on the viablecounts of total and fecal bacteria. Microbial aerosolemission from the surfaces of aeration tanks of anindustrial and municipal wastewater treatment plant(Como, Italy), at different seasons, was determined.This study was accomplished by conducting test runs inwhich SAS (Surface Air Systems, PBI) viable sampler,Sartorius MD8 with membrane gelatine filter andgravity method with Petri dishes were used to collectbacterial aerosol samples in situ. Total aerobicheterothropic bacteria, Mycetes, total and fecalcoliforms were determined. The preliminary resultsshow that: no correlation was found between the twodifferent passive and active culture techniques, dueto the different mechanisms of capture of bioaerosolagents on the media; optimal values for the recoveryof E. coli viable bacteria by MD8 samplerwith gelatine membrane, time and temperature ofstorage, were recognised. For the PCR technique, acouple of primers (URL 301–URR 432) to detect E. coli, on definite air samples, was used, operativeconditions were defined, and then, applied inmonitoring on in situ bioaerosol samples. At thewastewater plant, the highest total aerobic bacteriaemission rate during the preliminary mechanicaltreatments and in correspondence of the enclosedactivated sludge phase, as a consequence of theremarkable aeration of the tanks, were registered. Thesensitivity (82 CFU/m3) and rapidity (less than 8hours) of the biomolecular methods to determine thepresence and the fecal coliforms (E. coli) ratein bioaerosols was considered satisfactory.

Bioaerosol Concentrations in the Quad Cities 1 Year after the 1993 Mississippi River Floods

Abstract: Bioaerosol measurements were made in 45 Quad Cities, Illinois houses following the 1993 floods of the Mississippi and Rock Rivers. Least squares log transformed means for fungal concentrations (in cfu m–3) were 1,449 in basements, 1,174 in living rooms, 1,234 in kitchens, 1,464 in first floor bedrooms, 1,197 in second floor bedrooms, and 2,590 outside. Mean least squares log transformed bacterial concentrations were 887 cfu m–3 in basements, 878 cfu m–3 in living rooms and 697 cfu m–3 outdoors. Levels of fungi and bacteria were not notably elevated in the basements or other rooms of the formerly flooded houses. Levels of fungi and bacteria indoors were significantly less in houses with dehumidifiers and in homes with natural gas odors. Air-conditioning during warm periods significantly reduced airborne concentrations of fungi.

Emissions of fungal spores from biofilters of composting facilities.

Abstract: The biofilters of two compost plants were examined regarding their influence on the fungal spore concentrations in the bioaerosol of the emitted air of the plants when passing the biofilters. In all cases of a series of measurements there was a reduction in the spore concentration of Aspergillus fumigatus, but the spores of other fungi inhabiting the biofilters, particularly Paecilomyces species and Aureobasidium pullulans, were released into the emitted air. Thus in some cases the total number of spores was higher in the treated than in the untreated air, but in other cases it was reduced.

Air quality in swine-finishing barns.

Abstract: Air quality was assessed in two commercial swine-finishing barns: one naturally ventilated (NV) and one mechanically ventilated (MV). The concentrations of inhalable dust (IDC), respirable dust (RDC), airborne viable particles, carbon dioxide (CO2), and ammonia (NH3), as well as the air temperature and relative humidity (RH) inside the barns were monitored for 41 weeks. The two barns did not differ significantly (P>0.05) in IDC, RDC, and bioaerosol concentration. Overall mean levels for IDC, RDC, CO2, and NH3 were below the threshold limit values specified by the American Conference of Governmental Industrial Hygienists (ACGIH). However, some measurements exceeded the exposure limits suggested by previous researchers, especially during cold days. In general, the air quality in the two types of buildings was acceptable except under certain conditions (e.g., low ventilation rates during cold weather). In such case, workers and producers may need help or further training to ensure adequate air quality. In addition, under these conditions, workers should wear respiratory protective devices to minimize risk of inhalation of dust, gases, and bioaerosols.