Porcine reproductive and respiratory syndrome virus (PRRSV) causes disease in swine and economic losses for swine producers. An inexpensive and effective method for removing PRRSV from air is required to reduce aerosol transmission of PRRSV. A laboratory study was used to assess the performance of air ionization at removing bioaerosols contaminated with PRRSV. Aerosol properties were measured with an Aerosol Particle Size Spectrometer and air samples were collected with SKC biosamplers. PRRSV RNA was quantified with RNA extraction and quantitative reverse transcription polymerase chain reaction. Reduction in aerosol concentrations ranged from 61 – 93% by number count and 68 – 96% by mass. Initial particle size distribution and airflow rate affected the performance of EPI Air at reducing aerosol concentrations. Air ionization was effective at removing PRRSV from the air. The PRRSV RNA concentrations were reduced by 68 – 90% and the average PRRSV RNA after ionization ranged from 154 – 4594 VGCN/m3.

Norovirus is the most common pathogen to cause acute gastroenteritis in the world. Symptoms of acute gastroenteritis include vomiting and/or diarrhea, along with fever, abdominal pain, and malaise. Annually, norovirus causes 685 million cases of acute gastroenteritis and 200,000 deaths, worldwide. Among the 685 million cases occurring every year, 19-21 million occur in the United States. Norovirus can spread through direct or indirect contact (e.g., contaminated food or water). In addition, recent evidence has suggested that norovirus can also be spread via aerosolization. However, no study has determined an indoor generation source for aerosolized norovirus. Therefore, the goals of this study were to optimize sampling and quantification methods for the collection of aerosolized norovirus. Upon optimization, the last was to investigate a potential indoor generation source (i.e., toilet flushing) of aerosolized norovirus. To achieve this goal we devised three studies. In the first study, we optimized a sampling method for the collection of aerosolized norovirus using murine norovirus (MNV) as a surrogate. Optimization of the sampling method was performed using two bioaerosol samplers (SKC BioSampler and the National Institute for Occupational Safety and Health [NIOSH] Bioaerosol Cyclone Sampler 251) and two sampling media (Hanks Balanced Salt Solution [HBSS] and Phosphate Buffered Saline [PBS]). Murine norovirus was aerosolized in a bioaerosol chamber and later collected using the optimized sampler/media combination. After collection, viral RNA was extracted from MNV collected samples and quantified using quantitative polymerase chain reaction (qPCR). Intact capsids of MNV were assessed using propidium monoazide dye in combination with qPCR and confirmed with transmission electron microscopy. There were a total of 10 trials conducted, with each trial lasting for 30 minutes. The SKC BioSampler collected a significantly higher concentration of MNV than the NIOSH-251 sampler did (p-value < 0.0001). However, there were no significant differences in the relative percent of MNV that remained viable between both samplers (p-value = 0.2215). The use of HBSS sampling media yielded a higher concentration of MNV than PBS media (p-value = 0.0125). However, PBS media maintained viability at a significantly higher percentage than HBSS media (p-value < 0.0001). The results support the optimization of a sampling method for the collection of aerosolized MNV and possibly norovirus in different sampling environments. In the second study, we optimized the quantification method for MNV. A relatively new quantification system, droplet digital polymerase chain reaction (ddPCR), was evaluated using the same extracted samples collected in the first study to determine if the same overall outcome could be achieved. In addition, a MNV standard was directly compared between the qPCR and ddPCR. When comparing the same standard, the mean observed concentrations were similar to the nominal concentration. The limit of detection for both instruments was 5 copies per reaction. The coefficient of variation was lower across all ddPCR results than the qPCR results. The range of the R2 was larger for ddPCR compared to qPCR. As for the analysis of bioaerosol samples collected from the first study, the SKC BioSampler collected a significantly higher concentration of MNV compared to the NIOSH-251 sampler (p-value = 0.0002). However, there were no significant differences in the relative percent of MNV that remained viable in both samplers (p-value = 0.6734). The use of HBSS sampling media yielded a higher concentration of MNV than PBS media (p-value = 0.0190). However, PBS media maintained viability at a significantly higher percentage than HBSS media (p-value = 0.0004). The use of ddPCR allows for a simpler workflow and fewer samples and resources. These results support that both PCR systems yield similar results and overall outcomes, thus presenting an optimized quantification method for MNV. In the third study, we used the optimized sampling and quantification methods to conduct a field trial investigation of a potential indoor aerosolization source for norovirus (toilet flushing). To inform bioaerosol sampler placement, two optical particle counters monitored particle size and number distribution of aerosol produced from flushing a toilet across three variables (height, position, and side). The location with the highest mean particle concentration, and where bioaerosol sampling occurred, was behind the toilet and 0.15 m above the toilet bowl rim. A flushometer type toilet was seeded with 105 and 106 PFU/mL of MNV and then flushed. Upon flushing, a SKC BioSampler and Coriolis µ sampler were activated to collect aerosolized MNV. Samples were extracted and then quantified using RT-ddPCR, and viability was quantified using PMA: RT-ddPCR. The concentration of MNV collected after seeding the toilet water ranged from 2.18 x 105 – 9.65 x 106 total copies of MNV. Positive samples of airborne MNV were detected using the Coriolis µ sampler with collected concentrations ranging from 383 – 684 RNA copies/m3 of air. Sample viability for bioaerosol samples were unable to be quantified. The relative percent of MNV virions that remained intact in seeded toilet water was 37-79%. This study provides the first evidence that MNV, a NV surrogate, can be aerosolized when a toilet is flushed.

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Orientador: Maria Stella Gonçalves Raddi / Banca: Paulo Pinto Gontijo Filho / Banca: Carlos Henrique Gomes Martins / Resumo: Os principais parâmetros de qualidade do ar de um ambiente naturalmente ventilado e outro climatizado, destinados a ocupação comum, foram analisados. As variáveis ambientais consideradas foram concentração de bactéria (UFC/m3 de ar), concentração de fungo (UFC/m3 de ar), taxa de CO2 (ppm), umidade relativa do ar (%), velocidade (Km/h), temperatura (ºC) e concentração de partículas (æg/m3 de ar). Nossos achados apontam que os parâmetros mais influenciados pela ocupação dos ambientes são taxa de CO2 e concentração de aerossóis bacterianos, porém os valores médios no ambiente ventilado foram menores que no climatizado. Em decorrência da utilização, cada vez mais freqüente, de sistemas de condicionamento do ar, esse trabalho visou colaborar com o conhecimento dos principais parâmetros de qualidade de ar em ambientes climatizados e naturalmente ventilados. Para que a boa qualidade do ar de interiores possa ser mantida, em ambientes onde a ventilação é constante, é imprescindível o controle do número de ocupantes. / Abstract: The mainly environmentals parameters of the air quality in ventilatized and climatized ambients, destinated to the common occupation, were analyzed in this research. The evaluated environmental variables were the concentration of bacteria (CFU/m3 of air), concentration of fungo (CFU/m3 of air), rate of carbon dioxide (ppm), relative air humidity (%), speed (Km/h), temperature (ºC) and concentration of particles (æg/m3 of air). The correlation among the number of people, and the other variables, obtain significance, in the two samples, for the concentration of bacterial aerosols, CO2 rate and the temperature for the climatized ambient. In the ventilated ambient only the CO2 concentration and the number of people was correlated in the two samples. / Mestre

Electrostatic Dust Collectors (EDCs) are a passive sampling method that has not yet been fully validated. Our first study investigated the effect of EDC mailing and EDC deployment in front of and away from heated ventilation on endotoxin concentrations. Endotoxin sampling efficiency of heated and unheated EDC cloths was evaluated. EDCs express mailed cross-country yielded no significant changes in endotoxin concentrations when dust-only samples were compared to high quality control (QC) spiked-EDCs (p=0.21) and low QC spiked-EDCs (p=0.16). EDCs were deployed in 20 apartments with one EDC placed in front of the univent heater and another EDC placed on a built-in bookshelf. Endotoxin concentrations were significantly different (p=0.049) indicating that EDC placement impacts endotoxin sampling. Heated and unheated EDCs were deployed for 7 days in farm homes. There was a significant difference between endotoxin concentrations (p=0.027). The electrostatic charge of 12 heated and 12 unheated EDC cloths were significantly different (p=0.009). These studies suggest that heating cloths may diminish their electrostatic charge and endotoxin sampling capabilities. The EDC sampling time needed to achieve detectable and reproducible loading for bioaerosols has not been systematically evaluated. In our second study, EDCs were deployed in 15 Iowa farm homes for 7-, 14-, and 28-day sampling periods to determine if endotoxin and allergens could be quantified and if loading rates were uniform (i.e. doubling from 7 to 14 days and 14 to 28 days and quadrupling from 7 to 28 days). Loadings between left and right paired EDC cloths were not significantly different and were highly correlated for endotoxin, total protein, and cat (Fel d1), dog (Can f1) and mouse (Mus m1) allergens (p<0.001). EDC endotoxin sampling had close agreement between paired samples (Pearson p=0.96, p<0.001). EDC endotoxin loading doubled from 7 to 14-day deployments but the loading rate decreased from 14 to 28 days of sampling with only a 1.38 fold increase. Allergen exposure assessment using EDCs was less satisfactory. Paired EDCs and daily Button aerosol samplers (BS) were used in our third study to concurrently sample endotoxin in 10 farm homes during 7 day periods in summer and winter. Winter sampling included an optical particle counter (OPC) for particulate size and number concentration data. OPC particulate matter (PM) data were divided into PM2.5 and PM10-2.5. Summer sampling yielded geometric mean and geometric standard deviation values of 0.82 EU/m3 (2.7) for inhalable aerosol BS and 737 EU/m2 (1.9) for EDCs. Winter values were 0.52 EU/m3 (3.1) for BS and 538 EU/m2 (3.0) for EDCs. Seven day endotoxin values of EDCs were significantly and highly correlated with the 7-day BS sampling averages (p=0.70; p<0.001). An Analysis of Variance indicated a 2.37-fold increase in EDC endotoxin concentrations for each unit increase of the ratio of PM2.5 to PM10-2.5. A 10-fold increase in BS endotoxin concentrations was associated with a 12.2-fold increase in EDC endotoxin concentrations. Our fourth study established QC protocols use of EDCs in large field studies. QCs were developed for endotoxin, peptidoglycan, and glucan for analysis alongside the Agricultural Lung Health study EDC samples. The coefficient of variation percentage (CV) for each QC was used to determine variability. For each QC, 20 EDC cloths were analyzed to establish an acceptable range (mean ± 3 standard deviations). Two QCs were established for endotoxin analysis. The high QCs were dust-spiked EDCs with a CV of 29.7%. The low QCs were spiked with E. coli standard and had a CV of 15.6%. One QC was established for peptidoglycan analysis using dust-spiked EDC extracts. Two glucan QCs were established using dust-spiked EDCs with a high CV (51.7%) and yeast-spiked EDCs with a CV of 26.0%. Endotoxin and glucan concentrations of AGLH EDC samples were found to be significantly correlated (p=0.71; p<0.0001). In conclusion, EDCs are an effective passive sampling method for endotoxin exposure assessment in farm homes.

Two linear slot virtual impactor arrangements were developed and investigated in this study. Both arrangements encompassed two-stage impaction for concentration of bioaerosols. The first arrangement consisted of eight linear slot impactors in parallel for the first stage with the designed dimensions of 87 mm (3.4”) for the throat length, 0.305 mm (.012”) for the accelerator throat width, and 0.457 mm (.018”) for the receiver throat width. The second stage contained a single unit with the designed dimensions of 71 mm (2.8”) for the throat length, 0.36 mm (0.014”) for the accelerator throat width, and 0.49mm (0.019”) for the receiver throat width. The second arrangement contained a single impactor for the first stage with a designed throat length of 87 mm (3.4”), a designed accelerator throat width of 0.43 mm (.017”), and a designed receiver throat width of 0.63mm (.025”). The second stage also contained a single impactor with a designed throat length of 8.73 mm (3.4”), a designed accelerator throat width of .43 mm (.017), and a designed receiver throat width of 0.63 mm (0.25”). To verify the tolerances of the machined impactors, optical measurements were made. Both arrangements were subjected to liquid and solid particle tests and have a theoretical concentration factor of 100X. The arrangements were tested at flow rates that ranged from 10 L/min to 1000 L/min, where the collection efficiency of the minor flow was determined. An unknown acoustical phenomenon was present during aerosol tests at elevated flow rates causing low minor flow collection efficiencies. In order to test the impactors at elevated flow rates, the acoustical generation phenomenon was systematically studied and suppressed. The cutpoint for the first arrangement was 1.3µm AD, and the cutpoint for the second arrangement was 1.0 µm AD. The average Stk50 for both arrangements was 0.71. The throat velocity through the impactors ranged from 21.8 m/s to 73 m/s, and the peak efficiency for these specific throat velocities ranged from 99% to 74%, respectively.

Made available in DSpace on 2014-06-11T19:27:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-08-18Bitstream added on 2014-06-13T20:16:31Z : No. of bitstreams: 1 corbi_kp_me_arafcf.pdf: 422770 bytes, checksum: 6a87a5e20c6db8ffd363817b89326bde (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Universidade Estadual Paulista (UNESP) / Os principais parâmetros de qualidade do ar de um ambiente naturalmente ventilado e outro climatizado, destinados a ocupação comum, foram analisados. As variáveis ambientais consideradas foram concentração de bactéria (UFC/m3 de ar), concentração de fungo (UFC/m3 de ar), taxa de CO2 (ppm), umidade relativa do ar (%), velocidade (Km/h), temperatura (ºC) e concentração de partículas (æg/m3 de ar). Nossos achados apontam que os parâmetros mais influenciados pela ocupação dos ambientes são taxa de CO2 e concentração de aerossóis bacterianos, porém os valores médios no ambiente ventilado foram menores que no climatizado. Em decorrência da utilização, cada vez mais freqüente, de sistemas de condicionamento do ar, esse trabalho visou colaborar com o conhecimento dos principais parâmetros de qualidade de ar em ambientes climatizados e naturalmente ventilados. Para que a boa qualidade do ar de interiores possa ser mantida, em ambientes onde a ventilação é constante, é imprescindível o controle do número de ocupantes. / The mainly environmentals parameters of the air quality in ventilatized and climatized ambients, destinated to the common occupation, were analyzed in this research. The evaluated environmental variables were the concentration of bacteria (CFU/m3 of air), concentration of fungo (CFU/m3 of air), rate of carbon dioxide (ppm), relative air humidity (%), speed (Km/h), temperature (ºC) and concentration of particles (æg/m3 of air). The correlation among the number of people, and the other variables, obtain significance, in the two samples, for the concentration of bacterial aerosols, CO2 rate and the temperature for the climatized ambient. In the ventilated ambient only the CO2 concentration and the number of people was correlated in the two samples.

When inhaled, bioaerosols exacerbate respiratory symptoms and diseases. Mitigating the negative health impacts of bioaerosols requires a robust understanding of the temporal and spatial dynamics of bioaerosols in the atmosphere as a function of their type (e.g., bacteria, fungal spores, plant pollens) and particle size, which determines their penetration into the respiratory tract. While it is known that bioaerosol concentrations vary by location, season and meteorological conditions, major gaps remain in understanding the co-occurrence of bioaerosols with one another, their size in the atmosphere, and their mass contributions to PM. Overall, research presented in this thesis advances the current knowledge about bioaerosols (including fungal spores, pollens, and bacteria) in following ways: 1) defining background and urban levels of bioaerosol concentrations in the Midwestern US across four seasons, 2) characterizing ambient bioaerosol and co-pollutant mixtures, 3) determining the influence of meteorology on their concentrations and size distributions, and 4) estimating bioaerosol contributions to PM mass. The spatial analysis of respirable particulate matter (PM10) across urban and background sites in Iowa demonstrated that urban areas are a source of fungal glucans, bacterial endotoxins and total proteins, which gives rise to significantly enhanced bioaerosols in urban locations compared to background sites. Similar urban enhancements in calcium—a crustal element—and its correlation with endotoxins suggested that wind-blown soil is likely the origin. Seasonally, fungal spores peaked in summer with temperature, while bacterial endotoxins peaked in autumn during the row crop harvesting season. Fungal spores, bacterial endotoxins, plant and animal detritus all peaked during the growing season, such that maximum exposures to multiple bioaerosol types concurrently. Under the influence of rain chemical tracers of pollens peaked and decreased in size from coarse (2.5-10 µm) to fine particles (< 2.5 µm), likely due to the osmotic rupture of pollen grains upon wetting. While fine-sized fungal spores also increased during rain events, maximum spore levels were observed in coarse-sized particles post-rain. The comparison of spring to late summer measurements demonstrated these influences of precipitation on bioaerosols also occur during late summer, when fungal spore levels are high and ragweed is the dominant pollen source. The ability to apportion PM mass to bioaerosols was advanced through the development of chemical profiles of pollens and their integration with chemical mass balance (CMB) source apportionment modeling, for the first time. In late-April to early-May in 2013, pollens were estimated to contribute 0.2 - 38% of PM₁₀ (0.04 – 0.8 µg m⁻³) while fungal spores contributed 0.7 – 17% of PM₁₀ (0.1 – 1.5 µg m⁻³). Collectively, this thesis provides insight into spatial, seasonal and daily variations of bioaerosols, and shows elevated outdoor exposures to bioaerosols among urban populations, with maximum levels occurring during growing seasons, periods of high temperature, and during/immediately following rainfall.

Atmospheric aerosols have been studied in great depth in regards to its metrological and chemical characterizations. Covering about 33% of the planet, the Global Dust Belt is the major source of wind-blown dust. Airborne aerosols play important roles in the Earth systems, impacting the marine and terrestrial ecosystems, human and organismal health. Aerosolized dust can carry a diverse range of microorganisms that may be transported across large distances. If surviving the transport, influence, as vectors supporting microbial populations or as pathogens to other organisms, the recipient ecosystems where they may be delivered through dry and wet depositions. Located in the middle of the global dust belt area, the Red Sea receives about 1.2 Mt of emitted dust particles per storm and a total of 6 Mt dust deposition from the annual 5-6 storm events, which may contain important loads of microorganisms. This dissertation characterizes the taxonomical compositions of airborne prokaryotes and micro-eukaryotes and their transport history in the dust-associated microbiome, and the functional profile of the airborne microorganisms. The samples required to achieve these goals were collected with a high-volume dust collector over the Red Sea from the coastal and offshore regions over two years. In addition, microbial communities sampled from the surface Red Sea water were used to establish the possible relationship, suggesting an exchange, between the airborne microbial communities and those in the Red Sea. Since relying on culture5 based analyses would take no notice of unculturable microorganism, culture-independent techniques were followed to detect the vast majority of the biological particles on the sampled air filters. However, large volumes of air should be collected due to the difficulty of acquiring enough genomic materials from the low density of airborne microorganisms for molecular assays. Sahara Deserts and deserts in the Arabian Peninsula represented the major sources of microbial inputs to the Red Sea atmosphere. Hence, a high number of allergens, plant and mammalian pathogens, human and animal parasites have been detected in airborne dust samples, which could be of concern. Functionally, dust-associated microbiome has exclusive lifestyle’s features that facilitate a resilient strategy to survive during airborne transportation, so-called “aeolian lifestyle.”