Effectiveness of SplashGuard Caregiver prototype in reducing the risk of aerosol transmission in intensive care unit rooms of SARS-CoV-2 patients: a prospective and simulation study.

BACKGROUND: The contagiousness of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is known to be linked to the emission of bioaerosols. Thus, aerosol-generating procedures (AGPs) could increase the risk of infection among healthcare workers (HCWs). AIM: To investigate the impact of an aerosol protection box, the SplashGuard Caregiver (SGGC) with suction system, by direct analysis of the presence of viral particles after an AGP, and by using the computational fluid dynamics (CFD) simulation method. METHODS: This prospective observational study investigated HCWs caring for patients with SARS-CoV-2 admitted to an intensive care unit (ICU). Rooms were categorized as: SGCG present and SGCG absent. Virus detection was performed through direct analysis, and using a CFD model to simulate the movement dynamics of airborne particles produced by a patient's respiratory activities. FINDINGS: Of the 67 analyses performed, three samples tested positive on quantitative polymerase chain reaction: one of 33 analyses in the SCCG group (3%) and two of 34 analyses in the non-SGCG group (5.9%). CFD simulations showed that: (1) reduction of the gaps of an SGCG could decrease the number of emitted particles remaining airborne within the room by up to 70%; and (2) positioning HCWs facing the opposite direction to the main air flow would reduce their exposure. CONCLUSIONS: This study documented the presence of SARS-CoV-2 among HCWs in a negative pressure ICU room of an infected patient with or without the use of an SGCG. The simulation will help to improve the design of the SGCG and the positioning of HCWs in the room.

Effect of odor treatment systems on bioaerosol microbial concentration and diversity from wastewater treatment plants.

Biofiltration, activated carbon and chemical scrubbing are technologies used for odor control in wastewater treatment plants. These systems may also influence the airborne microbial load in treated air. The study objectives were to 1) evaluate the capacity of three odor control system technologies to reduce the airborne concentration of total bacteria, Legionella, L. pneumophila, non-tuberculous mycobacteria (NTM) and Cladosporium in winter and summer seasons and 2) to describe the microbial ecology of the biofiltration system and evaluate its impact on treated air microbial diversity. A reduction of the total bacterial concentration up to 25 times was observed after odor treatment. Quantification by qPCR revealed the presence of Legionella spp. in all air samples ranging between 26 and 1140 GC/m3, while L. pneumophila was not detected except for three samples below the limit of quantification. A significant increase of up to 25-fold of Legionella spp. was noticed at the outlet of two of the three treatment systems. NTM were ubiquitously detected before air treatment (up to 2500 GC/m3) and were significantly reduced by all 3 systems (up to 13-fold). Cladosporium was measured at low concentrations for each system (< 190 GC/m3), with 68 % of the air samples below the limit of detection. Biodiversity results revealed that biofiltration system is an active process that adapts to air pollutants over time. Legionella spp. were detected in significant abundance in the air once treated in winter (up to 27 %). Nevertheless, the abundance of protozoan hosts is low and does not explain the multiplication of Legionella spp. The season remains the most influential factor shaping biodiversity. In summer only, air biofiltration caused a significant enrichment of the biodiversity. Although odor control technologies are not designed for bacterial mitigation, findings from this study suggest their potential to reduce the abundance of some genera harboring pathogenic species.

Production of recycled manure solids for use as bedding in Canadian dairy farms: II. Composting methods.

Recent technological advances in the dairy industry have enabled Canadian farms with liquid manure systems to use mechanical solid-liquid separation paired with composting of the separated solids for on-farm production of low-cost bedding material. However, because several approaches are available, it is difficult for farmers to select the appropriate one to achieve high quality recycled manure solids (RMS). Whereas 3 solid-liquid manure separators were compared in part I of the series (companion paper in this issue), the present study (part II) aims to assess the performance of 4 composting methods (static or turned windrow and drum composter for 24 or 72 h) under laboratory conditions. Parameters evaluated included temperature, physico-chemical characteristics, and bacterial composition of RMS, as well as airborne microorganisms, dust, and gases associated with composting RMS. Because each treatment attained the desired composting temperature range of 40 to 65°C (either in heaps or in the drum composter), reductions in bacteria were a better indicator of the sanitation efficiency. The treatment of fresh RMS in a drum composter for 24 h showed decreased bacterial counts, especially for Escherichia coli (from 1.0 × 105 to 2.0 × 101 cfu/g of dry matter) and Klebsiella spp. (from 3.2 × 104 to 4.0 × 102 cfu/g of dry matter). Increasing the time spent in the rotating vessel to 72 h did not result in further decreases of these pathogens. Composting in a static or turned windrow achieved similar E. coli and Klebsiella spp. reductions as the 24-h drum composting but in 5 or 10 d, and generally showed the lowest occupational exposure risk for dairy farmers regarding concentrations of airborne mesophilic bacteria, mesophilic and thermotolerant fungi, and total dust. Drum-composted RMS stored in piles exhibited intermediate to high risk. Composting approaches did not have a major influence on the physico-chemical characteristics of RMS and gas emissions. Drum composting for 24 h was the best compromise in terms of product quality, temperature reached, decreased bacterial numbers, and emitted airborne contaminants. However, because levels of pathogenic agents rapidly increase once composted RMS are spread in stalls, bacteriological characteristics of RMS along with milk quality and animal health and welfare features should be monitored in Canadian dairy barns applying recommended separation (part I) and composting (part II) systems to evaluate health risk and optimize management practices.

A sphingosine-1-phosphate receptor 1 agonist inhibits tertiary lymphoid tissue reactivation and hypersensitivity in the lung.

Hypersensitivity pneumonitis is characterized by pulmonary accumulation of B-cell-rich tertiary lymphoid tissues (TLTs), which are alleged sites of amplification for antigen-specific responses. The sphingosine-1-phosphate receptor 1 (S1P1) regulates key mechanisms underlying lymphoid tissue biology and its chemical modulation causes lymphocyte retention in lymph nodes. Given the putative immunopathogenic impact of lymphocyte accumulation in TLTs, we investigated whether or not chemical modulation of S1P1 caused lymphocyte retention within TLTs in a model of hypersensitivity pneumonitis. Mice were exposed subchronically to Methanosphaera stadtmanae (MSS) in order to induce an hypersensitivity pneumonitis-like disease. MSS exposure induced B-cell-rich TLTs surrounded by S1P1-positive microvessels. Upon MSS rechallenge, the S1P1 agonist RP001 prevented the pulmonary increase of CXCL13, a chief regulator of B-cell recruitment in lymphoid tissues. This was associated with a complete inhibition of MSS rechallenge-induced TLT enlargement and with a 2.3-fold reduction of MSS-specific antibody titers in the lung. Interference with TLT reactivation was associated with a 77% reduction of neutrophil accumulation and with full inhibition of protein-rich leakage in the airways. Thus, an S1P1 agonist hinders TLT enlargement upon antigenic rechallenge and inhibits key pathognomonic features of experimental hypersensitivity pneumonitis.

Preferential aerosolization of bacteria in bioaerosols generated in vitro.

AIMS: Little is known about how bacteria are aerosolized in terms of whether some bacteria will be found in the air more readily than others that are present in the source. This report describes in vitro experiments to compare aerosolization rates (also known as preferential aerosolization) of Gram-positive and Gram-negative bacteria as well as rod- and coccus-shaped bacteria, using two nebulization conditions. METHODS AND RESULTS: A consortium of five bacterial species was aerosolized in a homemade chamber. Aerosols generated with a commercial nebulizer and a homemade bubble-burst aerosol generator were compared. Data suggest that Pseudomonas aeruginosa was preferentially aerosolized in comparison to Moraxella catarrhalis, Lactobacillus paracasei, Staphylococcus aureus and Streptococcus suis, independently of the method of aerosolization. Bacterial integrity of Strep. suis was more preserved compared to other bacteria studied as revealed with PMA-qPCR. CONCLUSION: We reported the design of an aerosol chamber and bubble-burst generator for the in vitro study of preferential aerosolization. In our setting, preferential aerosolization was influenced by bacterial properties instead of aerosolization mechanism. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings could have important implications for predicting the composition of bioaerosols in various locations such as wastewater treatment plants, agricultural settings and health care settings.

Masked hypertension and effort-reward imbalance at work among 2369 white-collar workers.

Hypertension is an important risk factor of cardiovascular diseases, the leading cause of death worldwide. Adverse effects of psychosocial factors at work might increase the risk of masked hypertension, but evidences are still scarce. The objective of this study is then to determine whether adverse psychosocial work factors from the effort-reward imbalance (ERI) model are associated with the prevalence of masked hypertension in a population of white-collar workers. White-collar workers were recruited from three public organizations. Blood pressure was measured at the workplace for manually operated measurements (mean of the first three readings taken by a trained assistant) followed by ambulatory measurements (mean of all subsequent readings taken during the working day). Masked hypertension was defined as manually operated BP<140/90 mm Hg and ambulatory BP ⩾135/85 mm Hg. ERI exposure at work was measured using Siegrist's validated questionnaire. Blood pressure readings were obtained from 2369 workers (participation proportion: 85%). ERI exposure (OR: 1.53 (95% CI: 1.16-2.02) and high efforts at work (OR: 1.61 (95% CI: 1.13-1.29) were associated with masked hypertension, after adjusting for sociodemographic and cardiovascular risk factors. Workers exposed to an imbalance between efforts spent at work and reward had a higher prevalence of masked hypertension. High efforts at work might be of particular importance in explaining this association. Future studies should be designed to investigate how clinicians can include questions on psychosocial work factors to screen for masked hypertension and how workplace interventions can decrease adverse psychosocial exposures to lower BP.

Bioaerosols in the Barcelona subway system.

Subway systems worldwide transport more than 100 million people daily; therefore, air quality on station platforms and inside trains is an important urban air pollution issue. We examined the microbiological composition and abundance in space and time of bioaerosols collected in the Barcelona subway system during a cold period. Quantitative PCR was used to quantify total bacteria, Aspergillus fumigatus, influenza A and B, and rhinoviruses. Multitag 454 pyrosequencing of the 16S rRNA gene was used to assess bacterial community composition and biodiversity. The results showed low bioaerosol concentrations regarding the targeted microorganisms, although the bacterial bioburden was rather high (104 bacteria/m3 ). Airborne bacterial communities presented a high degree of overlap among the different subway environments sampled (inside trains, platforms, and lobbies) and were dominated by a few widespread taxa, with Methylobacterium being the most abundant genus. Human-related microbiota in sequence dataset and ascribed to potentially pathogenic bacteria were found in low proportion (maximum values below 2% of sequence readings) and evenly detected. Hence, no important biological exposure marker was detected in any of the sampled environments. Overall, we found that commuters are not the main source of bioaerosols in the Barcelona subway system.

Identification of dichloroacetic acid degrading Cupriavidus bacteria in a drinking water distribution network model.

AIMS: Bacterial community structure and composition of a drinking water network were assessed to better understand this ecosystem in relation to haloacetic acid (HAA) degradation and to identify new bacterial species having HAA degradation capacities. METHODS AND RESULTS: Biofilm samples were collected from a model system, simulating the end of the drinking water distribution network and supplied with different concentrations of dichloroacetic and trichloroacetic acids at different periods over the course of a year. The samples were analysed by culturing, denaturing gradient gel electrophoresis (DGGE) and sequencing. Pipe diameter and HAA ratios did not impact the bacterial community profiles, but the season had a clear influence. Based on DGGE profiles, it appeared that a particular biomass has developed during the summer compared with the other seasons. Among the bacteria isolated in this study, those from genus Cupriavidus were able to degrade dichloroacetic acid. Moreover, these bacteria degrade dichloroacetic acid at 18°C but not at 10°C. CONCLUSIONS: The microbial diversity evolved throughout the experiment, but the bacterial community was distinct during the summer. Results obtained on the capacity of Cupriavidus to degrade DCAA only at 18°C but not at 10°C indicate that water temperature is a major element affecting DCAA degradation and confirming observations made regarding season influence on HAA degradation in the drinking water distribution network. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first demonstration of the HAA biodegradation capacity of the genus Cupriavidus.

Metalworking fluids biodiversity characterization.

AIMS: Hypersensitivity pneumonitis of machinists associated with metalworking fluids (MWF) was recently linked to Mycobacterium immunogenum. In addition to Mycobacterium, impacts of continuous and massive contact to other micro-organisms, such as Pseudomonas, were little studied. This report intended to quantify and characterize the microbial load of 44 in-use MWF. METHODS AND RESULTS: The main biodiversity of MWF was assessed using cultural methods, quantitative PCR (qPCR) and denaturing gradient gel electrophoresis (DGGE). Total bacteria concentrations ranged from undetectable to 10(9) 16S rRNA gene copies per millilitre. Concentrations obtained by qPCR were up to five orders of magnitude higher than by culture, suggesting that MWF contamination is generally underestimated. Two samples showed high concentrations of Myco. immunogenum (1.55 x 10(7) and 3.49 x 10(5) 16S rRNA gene copies per millilitre). The overall biodiversity was low, as observed by culture and DGGE, and was comparable to data found in the literature. Pseudomonas pseudoalcaligenes was by far the main bacteria found in MWF samples (33 out of 44), followed by Ochrobactrum anthropi (32 out of 44). There was no significant relationship between the biodiversity profiles and the kind of MWF or equipment used, making it difficult to predict which micro-organisms will colonize each particular MWF. CONCLUSIONS: Very high concentrations of bacteria were found in most MWF studied and limited biodiversities were observed. Many species of micro-organisms were retrieved from MWF samples, but they were mostly colonized by Pseudomonas pseudoalcaligenes and Ochrobactrum anthropi. SIGNIFICANCE AND IMPACT OF THE STUDY: The major micro-organisms observed or recovered in this study from in-use MWF were present in very high concentrations, and thus further studies are needed to confirm their role in workers' respiratory disorders or health-related problems.

Real-time PCR quantification of Mycobacterium immunogenum in used metalworking fluids.

Rapid detection and quantification of Mycobacterium immunogenum in field samples of metalworking fluids (MWFs) is important for factory fluid surveillance programs. The applicability of the developed DNA extraction and quantitative real-time PCR (qPCR) methods to detect and quantify M. immunogenum in used MWFs was evaluated. Total DNA from these samples was extracted, and M. immunogenum measured by qPCR by comparison with a standard curve derived from plasmid vectors. PCR counts were compared with bacterial culture counts. PCR counts of M. immunogenum varied from 1.42 x 10(3) to 3.68 x 10(6) cells/mL of MWFs. Recovery of M. immunogenum by bacterial culture varied from 2.5% to 70% of qPCR count in corresponding samples. Quantitative PCR could be used to measure M. immunogenum load in MWF samples with greater sensitivity and shorter processing time than the classic bacterial culture-based approach. The proposed qPCR approach could be routinely used in real-time PCR-equipped laboratories to provide early detection of M. immunogenum and to control proliferation that probably leads to hypersensitivity pneumonitis in exposed workers.

Molecular Detection of Phytophthora ramorum by Real-Time Polymerase Chain Reaction Using TaqMan, SYBR Green, and Molecular Beacons.

ABSTRACT Sudden oak death, caused by Phytophthora ramorum, is a severe disease that affects many species of trees and shrubs. This pathogen is spreading rapidly and quarantine measures are currently in place to prevent dissemination to areas that were previously free of the pathogen. Molecular assays that rapidly detect and identify P. ramorum frequently fail to reliably distinguish between P. ramorum and closely related species. To overcome this problem and to provide additional assays to increase confidence, internal transcribed spacer (ITS), beta-tubulin, and elicitin gene regions were sequenced and searched for polymorphisms in a collection of Phytophthora spp. Three different reporter technologies were compared: molecular beacons, TaqMan, and SYBR Green. The assays differentiated P. ramorum from the 65 species of Phytophthora tested. The assays developed were also used with DNA extracts from 48 infected and uninfected plant samples. All environmental samples from which P. ramorum was isolated by PARP-V8 were detected using all three real-time PCR assays. However, 24% of the samples yielded positive real-time PCR assays but no P. ramorum cultures, but sequence analysis of the coxI and II spacer region confirmed the presence of the pathogen in most samples. The assays based on detection of the ITS and elicitin regions using TaqMan tended to have lower cycle threshold values than those using beta-tubulin and seemed to be more sensitive.

Detection of Legionella spp. by fluorescent in situ hybridization in dental unit waterlines.

AIMS: To confirm the presence of viable Legionella spp. in dental unit waterlines (DUWL) using fluorescent in situ hybridization (FISH) and compare this method with culture approach and also to validate the utility of an enrichment to increase FISH sensitivity. METHODS AND RESULTS: Water samples from 40 dental units were analysed. Three different techniques for detecting Legionella spp. were compared: (i) culture approach, (ii) direct FISH and (iii) FISH with a previous R2A medium enrichment (R2A/FISH). The FISH detection was confirmed by PCR. The use of the direct FISH does not improve significantly the detection of legionellae when compared with the culture. On the contrary, when R2A/FISH was performed, sensitivity was, respectively, two- and threefold higher than that with the direct FISH and culture approach. Using R2A/FISH, 63% of water samples analysed showed a contamination by legionellae. CONCLUSIONS: Legionellae detection by direct FISH and R2A/FISH in dental unit water is possible but is more rapid and more sensitive (R2A/FISH) than the culture approach. SIGNIFICANCE AND IMPACT OF THE STUDY: R2A/FISH showed that several pathogens present in DUWL are viable but may not be culturable. Unlike PCR, R2A/FISH is designed to detect only metabolically active cells and therefore provides more pertinent information on infectious risk.

Assessment of bacterial endospore viability with fluorescent dyes.

AIM: To validate three fluorescence viability assays designed primarily for vegetative cells on pure Bacillus endospores. METHODS AND RESULTS: Purified fresh and gamma-irradiated Bacillus endospores (Bacillus cereus, B. coagulans and two strains of B. subtilis) were used. The viability assays were: 5-cyano-2,3-diotolyl tetrazolium chloride (CTC) to test respiratory activity and early germination, DiBAC4(3) and Live/Dead BacLight to measure membrane energization and permeabilization, respectively. Gamma irradiation treatment completely eliminated spore culturability and was used as negative control. The untreated spores showed respiratory activity after 1 h of incubation and this was characteristic of almost 100% of spores after 24 h. The membrane potential assessment gave no answer about spore viability. A lower proportion of untreated spores had permeabilized membrane compared with gamma-irradiated spores using Live/Dead BacLight (P < 0.02). CONCLUSION: It is possible to use CTC and Live/Dead BacLight to rapidly test endospore viability and evaluate the proportion of spores in a preparation that could not be recovered with plate count. SIGNIFICANCE AND IMPACT OF THE STUDY: This study shows that fluorescence tests could be applied to assess viability in potentially pathogenic Bacillus spore preparations within 1 h.

Random amplified ribosomal DNA restriction analysis for rapid identification of thermophilic Actinomycete-like bacteria involved in hypersensitivity pneumonitis.

Hypersensitivity pneumonitis (HP) is a pulmonary disease characterised by inflammation that can be caused by, amongst other substances, a subset of 4 thermophilic mycelial bacteria: Saccharopolyspora rectivirgula, Saccharomonospora viridis, Thermoactinomyces sacchari, and Thermoactinomyces vulgaris. Air sampling analyses in highly contaminated environments are often performed to evaluate exposure to these species which are difficult and fastidious to identify by conventional techniques. The aim of this study was to use amplified ribosomal DNA restriction analysis (ARDRA) to develop a method of identification for those thermophilic organisms that would be more rapid and simple. Strains of these 4 species were obtained from the American type culture collection (ATCC) and were characterized using biochemical tests and ARDRA patterns obtained on their partial-lenght amplified 16S rDNAs. To validate this approach, ARDRA with two restriction enzymes, TaqI and HhaI, was applied to 49 thermophilic actinomycete-like strains from environmental samples (sawmills). The results obtained show that combining some cultural characteristics and biochemical tests, such as xanthine or hypoxanthine decomposition, growth in the presence of NaCl, lysozyme or novobiocin, and spore resistance over 100 degrees C provide a rough identification and selection of the genera of interest. Consequently, target species could be confirmed by digestion of partial-lenght 16S rDNA with the use of Taql and HhaI restriction enzymes that gave specific restriction patterns. ARDRA analyses on the 49 environmental actinomycete-like organisms revealed the presence of 8 Saccharopolyspora rectivirgula, 2 Saccharomonospora viridis, and 15 Thermoactinomyces vulgaris strains, the other strains had restriction patterns different than those of the species of interest. Results of the present study will be applicable to other potential HP environments such as dairy barns, peat bogs and compost plants.

Comparison of endotoxin exposure assessment by bioaerosol impinger and filter-sampling methods.

Environmental assessment data collected in two prior occupational hygiene studies of swine barns and sawmills allowed the comparison of concurrent, triplicate, side-by-side endotoxin measurements using air sampling filters and bioaerosol impingers. Endotoxin concentrations in impinger solutions and filter eluates were assayed using the Limulus amebocyte lysate assay. In sawmills, impinger sampling yielded significantly higher endotoxin concentration measurements and lower variances than filter sampling with IOM inhalable dust samplers. Analysis of variance for repeated measures showed that this association remained after controlling for other factors such as replicate, sawmill, sawmill operation, wood type, and interaction terms. Endotoxin concentrations in the swine barns were 10-fold higher on average than in sawmills. These samples demonstrated comparable endotoxin concentration estimates for impinger and filter methods although the variability was lower using the impinger method. In both occupational settings, side-by-side replicates were more uniform for the impinger samples than for the filter samples. This study demonstrates that impinger sampling is an acceptable method for quantitation of area endotoxin concentrations. Further, when sampling is performed with impingers for airborne microorganism quantitation, these same impinger solutions can yield valid endotoxin exposure estimates, negating the need for additional filter sampling.

Respiratory health impact of working in sawmills in eastern Canada.

Air contamination in sawmills can cause respiratory health problems. The authors measured respirable dust, bacteria, endotoxins, and molds collected from 17 sawmills in eastern Canada. A total of 1,205 sawmill workers answered a respiratory-health questionnaire, and they all participated in lung-function measurements, skin-prick tests, and venous blood sampling for specific immunoglobulins against molds found in the sawmills. Workers had normal lung functions, and most respiratory symptoms could be explained by smoking histories. Workers in pine sawmills had a greater prevalence of positive skin-prick test to pine than did workers in sawmills where other woods were used. High levels of specific antibodies were seen in some workers. The presence of a positive skin-prick test and/or specific antibodies had no impact on lung function(s). These Quebec sawmill workers did not experience significant respiratory illnesses; however, some of these workers may be at a higher risk of developing asthma and hypersensitivity pneumonitis than nonworkers.

Assessment of particulates and bioaerosols in eastern Canadian sawmills.

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 x 10(6) CFU/m3, whereas the median values for culturable bacteria and endotoxin were 21,620 CFU/m3 and 1,081 endotoxin units/m3, respectively. Planing sites were the most highly dust contaminated (median: 3.0 mg/m3) (p <0.05). Sawmills of eastern Canada contain airborne biological contaminants that vary between working sites, and their microflora is different from that previously described in European sawmills.

Airborne microfungi from eastern Canadian sawmills.

Working in sawmills is associated with bioaerosol exposure and respiratory health problems. This study is the first to analyze the mycoflora of eastern Canadian sawmills and the nature of airborne contamination at different work sites. Fifty work sites (debarking, sawing, planing, and sorting) within 17 sawmills were sampled for airborne microfungi. One thousand seven hundred strains were isolated, quantified to determine the frequency of occurrence, and then identified. Unlike the European studies, we did not frequently identify the presence of fungi that were described in European sawmills as being related to respiratory health problems. In eastern Canadian sawmills, Penicillium species are the most frequently isolated microfungi.

Farming practices and the respiratory health risks of swine confinement buildings.

This study investigated whether clean swine confinement buildings (SCB) are less harmful to the respiratory system than older and dirtier facilities. Eight healthy volunteers were exposed for 4 h, at 1 week intervals, to eight SCB representing the widest possible range of cleanliness. Each volunteer and a technician rated the SCB for cleanliness from 1-10, 1 being the cleanest possible. Airborne dust, bacteria, endotoxin levels, molds, and ammonia were measured. For each volunteer measured, before and after each exposure, forced expiratory flows (forced expiratory volume in one second (FEV1), and forced vital capacity), white cells in nasal wash and venous blood, and nasal lavage levels of interleukin (IL)-8 and serum levels of IL-6. A methacholine challenge was obtained at baseline and following each exposure. Cleanliness scores ranged 1.5-8.25. Mean airborne levels were: dust 3.54 mg x m(-3) bacteria 4.25 x 10(5) CFU x m(-3); endotoxins 404 EU x m(-3); molds 883 CFU x m(-3); ammonia 20.7 parts per million (ppm). Expiratory flows decreased after exposure (FEV1 from 4.8+/-0.7 to 4.4+/-0.7, p<0.001), neutrophils in the nasal wash and white blood cells increased (28.5+/-37 to 424+/-207 x 10(3), 5.4+/-1.0 to 7.4+/-1.7 x 10(9) cells x mL(-1) respectively), IL-8 increased from 158+/-311 to 2679+/-639 pg x mL(-1), IL-6 from 0.15+/-0.26 to 2.34+/-0.92 pg x mL(-1), (p<0.001). All SCB were similarly harmful. In conclusion, modern farming has not succeeded in making swine confinement buildings inoffensive to exposed subjects.

Influence of building maintenance, environmental factors, and seasons on airborne contaminants of swine confinement buildings.

Eight swine confinement buildings, selected to cover the widest possible range of cleanliness, were visited twice during winter and once during summer to verify the range, seasonal variations, and correlations between biological and chemical contaminants. Physical aspects were graded for dirtiness (1 = clean, 10 = dirty), ventilation, air temperature, number of animals, building, and room size. Air samples were taken to measure relative humidity, CO2, ammonia, total dust, and microbiological counts and/or identification (bacteria and molds); endotoxin levels also were measured. During winter, average measurements and ranges were: CO2 = 0.304% (0.254 to 0.349%); ammonia = 19.6 ppm (1.9 to 25.9 ppm); dust = 3.54 mg/m3 (2.15 to 5.60 mg/m3). There were 883 cfu/m3 (547 to 2862 cfu/m3) of molds, 4.25 x 10(5) cfu/m3 (1.67 x 10(5) to 9.30 x 10(5) cfu/m3) of total bacteria, 29 cfu/m3 (3 to 94 cfu/m3) of thermophilic actinomycetes). A significant decrease in bacterial levels (p = 0.04), dust (p = 0.0008), ammonia (p = 0.005), and CO2 (p < 0.0001) was observed during summer sampling when compared with winter levels. Mold counts were positively correlated (p = 0.03) with dirtiness scores, while bacterial counts were negatively correlated with this parameter (p < 0.002), whereas bacteria and endotoxins were correlated with the number of animals (p < 0.05). Ambient gases (CO2 and ammonia) correlated with each other (p = 0.006). Bacteria were the most important contaminant in swine confinement buildings, and endotoxin levels found were also very high (mean = 4.9 x 10(3) EU/m3). We conclude that a wide range of air contamination exists in swine confinement buildings of different maintenance. There is a decrease in some of these contaminants during summer. Observed dirtiness of the swine confinement buildings has a poor predictive value concerning air quality.