Use of (1-3)-beta-d-glucan concentrations in dust as a surrogate method for estimating specific fungal exposures

Indoor exposure to fungi has been associated with respiratory symptoms,often attributed to their cell wall component, (1-3)-beta-D-glucan. Performing(1-3)-beta-D-glucan analysis is less time consuming and labor intensive than cultivation or microscopic counting of fungal spores. This has prompted many to use(1-3)-beta-D-glucan as a surrogate for fungal exposure. The aim of this study was to examine which indoor fungal species are major contributors to the (1-3)-beta-D-glucan concentration in field dust samples. We used the quantitative polymerase chain reaction (QPCR) method to analyze 36 indoor fungal species in 297 indoor dust samples. These samples were also simultaneously analyzed for (1-3)-beta-D-glucan concentration using the endpoint chromogenic Limulus Amebocyte lysate assay. Linear regression analysis, followed by factor analysis and structural equation modeling, were utilized in order to identify fungal species that mostly contribute to the (1-3)-beta-D-glucan concentration in field dust samples. The study revealed that Cladosporium and Aspergillus genera, as well as Epicoccum nigrum, Penicillium brevicompactum and Wallemia sebi were the most important contributors to the (1-3)-beta-D-glucan content of these home dust samples. The species that contributed most to the (1-3)-beta-D-glucan concentration were also the most prevalent in indoor environments. However, Alternaria alternata, a common fungal species in indoor dust, did not seem to be a significant source of (1-3)-beta-D-glucan. PRACTICAL IMPLICATIONS: This study revealed that the (1-3)-beta-D-glucan content of different fungal species varies widely. (1-3)-beta-D-glucan inhouse dust from the Greater Cincinnati area may be a good marker for some fungal species of the Cladosporium and Aspergillus genera. In contrast, Alternaria alternata did not contribute much to the (1-3)-beta-D-glucan load. Therefore, (1-3)-beta-D-glucan concentration in field samples as a surrogate for total fungal exposure should be used with caution.     

Determinants of house dust,endotoxin, and β‐(1→3)‐D‐glucan in homes of Danish children

Little is known about the geographic variation and determinants of bacterial endotoxin and β ‐(1,3)‐d ‐glucan in Danish house dust. In a population of 317 children, we: (i) described loads and concentrations of floor dust, endotoxin, and β‐(1→3)‐d ‐glucan and (ii) their correlations and (iii) assessed their determinants; (iv) Finally, we compared our findings with previous European studies. Bedroom floor dust was analyzed for endotoxin content by the kinetic limulus amoebocyte lysate assay and for β‐(1→3)‐d ‐glucan by the inhibition enzyme immunoassay. The parents answered questions regarding potential determinants. We found: geometric means (geometric standard deviations) 186 mg/m² (4.3) for dust; 5.46 × 10³EU/m² (8.0) and 31.1 × 10³EU/g (2.6) for endotoxin; and 142 μg/m² (14.3) and 0.71 × 10³ μg/g (7.3) for β‐(1→3)‐d ‐glucan. High correlations (r > 0.75) were found between floor dust and endotoxin and β‐(1→3)‐d ‐glucan loads, while endotoxin and β‐(1→3)‐d ‐glucan concentrations were moderately correlated (r = 0.36–0.41) with the dust load. Having a carpet was positively associated with dust load and with endotoxin and β‐(1→3)‐d ‐glucan concentrations. Pet keeping, dwelling type, and dwelling location were determinants of endotoxin concentrations. No other determinants were associated with β‐(1→3)‐d ‐glucan concentrations. Compared with other European studies, we found lower β‐(1→3)‐d ‐glucan loads and concentrations but higher endotoxin loads and concentrations suggesting a geographically determined different composition of Danish floor dust compared with other European regions.     

Endotoxin and β(1→3)-Glucan in House Dust and the Relation with Home Characteristics: A Pilot Study in 25 German Houses

Abstract Residential microbial exposure has been suggested to be involved in the development of asthma. This paper describes bacterial endotoxin and mold β(1→3)-glucan levels in house dust and the relationship to selected home characteristics. Dust was sampled from mattresses and living room and bedroom floors of 25 houses in Germany. Endotoxin and β(1→3)-glucan levels ranged from 200-48,600 EU/g dust (100-32,900 EU/m² sampled surface) and 182-3,507 μg/g (157-3,652 μg/m²), respectively. Bio-contaminant levels were highest on living room floors and lowest in mattresses. Dust, endotoxin and β(1→3)-glucan levels were 2–3 times higher on living room floors of centrally heated houses built after 1970 compared to older individually heated houses. This was not found for mattresses and bedroom floors. No associations between biocontaminant levels and other selected home characteristics (temperature, relative humidity, damp spots and insulation of windows) were found. β(1→3)-glucan levels were associated with total culturable fungi (per m²) in house dust, as well as with the fungal genus Alternaria (per g dust and per m²). In conclusion endotoxin and β(1→3)-glucan were readily detectable in house dust and significantly associated with heating system and/or age of the home.     

Associations between evaporative cooling and dust‐mite allergens,endotoxins, and β‐(1 → 3)‐d‐glucans in house dust: A study of low‐income homes

Recent work suggests that evaporative coolers increase the level and diversity of bioaerosols, but this association remains understudied in low‐income homes. We conducted a cross‐sectional study of metropolitan, low‐income homes in Utah with evaporative coolers (n = 20) and central air conditioners (n = 28). Dust samples (N = 147) were collected from four locations in each home and analyzed for dust‐mite allergens Der p1 and Der f1, endotoxins, and β‐(1 → 3)‐d ‐glucans. In all sample locations combined, Der p1 or Der f1 was significantly higher in evaporative cooler versus central air conditioning homes (OR = 2.29, 95% CI = 1.05‐4.98). Endotoxin concentration was significantly higher in evaporative cooler versus central air conditioning homes in furniture (geometric mean (GM) = 8.05 vs 2.85 EU/mg, P < .01) and all samples combined (GM = 3.60 vs 1.29 EU/mg, P = .03). β‐(1 → 3)‐d ‐glucan concentration and surface loads were significantly higher in evaporative cooler versus central air conditioning homes in all four sample locations and all samples combined (P < .01). Our study suggests that low‐income, evaporative cooled homes have higher levels of immunologically important bioaerosols than central air‐conditioned homes in dry climates, warranting studies on health implications and other exposed populations.     

Dampness in buildings as a risk factor for health effects, EUROEXPO: a multidisciplinary review of the literature (1998-2000) on dampness and mite exposure in buildings and health effects

The scientific literature on health effects from dampness in buildings, including mite exposure over the period 1998-2000 has been reviewed by an European group (EUROEXPO) of eight scientists in experience from medicine, epidemiology, toxicology and engineering. Forty studies deemed relevant have been the foundation for the conclusions. Dampness in buildings is a risk factor for health effects among atopics and non-atopics both in domestic and in public environments. However, the literature is not conclusive in respect of causative agents, e.g. mites, microbiological agents and organic chemicals from degraded building materials. There is a strong need for more multidisciplinary studies including expertise from all relevant areas. A general conclusion from the work was that there is a strong need for multidisciplinary reviews in scientific journals of articles dealing with associations between indoor environmental factors and health effects. PRACTICAL IMPLICATIONS: There is good evidence for a true association between dampness in buildings and health. As the causative factors behind this association are not known, the main focus in practical investigations should be on finding out and remediate the reasons for the humidity problem.     

Surface chemistry reactions of alpha-terpineol [(R)-2-(4-methyl-3-cyclohexenyl)isopropanol] with ozone and air on a glass and a vinyl tile

The surface-phase reaction products of alpha-terpineol [(R)-2-(4-methyl-3-cyclohexenyl)isopropanol] with ozone (O(3)), air or nitrogen (N(2)) on both a glass and vinyl flooring tile were investigated using the recently published FLEC Automation and Control System (FACS). The FACS was used to deliver O(3) (100 ppb), air or N(2) to the surface at a specified flow rate (300 ml/min) and relative humidity (50%) after application of a 1.6%alpha-terpineol solution in methanol. Oxidation products were detected using the derivatization agents: O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine and N,O-bis(trimethysilyl)trifluoroacetamide. The positively identified reaction products were glyoxal, methylglyoxal and 4-oxopentanal. The proposed oxidation products based on previously published VOC/O(3) reaction mechanisms were: 4-methylcyclohex-3-en-1-one, 6-hydroxyhept-en-2-one, 3-(1-hydroxy-1-methylethyl)-6-methylcyclohex-2-en-1-one) and one surface-enhanced reaction product: 5-(1-hydroxy-1-methylethyl)-2-methylcyclohex-2-en-1-one. Though similar products were observed in gas-phase alpha-terpineol/O(3) reactions, the ratio of the reaction products were different suggesting stabilization of larger molecular weight species by the surface. Emission profiles of these oxidation products over 72 h are also reported. PRACTICAL IMPLICATIONS: Volatile organic compounds (VOCs) can interact with indoor initiators [such as hydroxyl radicals (OH*), ozone and nitrate radicals (NO(3)*)] to form a number of oxygenated by-products in the gas-phase. However, when VOCs are applied to or are present on the surface, heterogeneous chemistry with indoor initiators can also occur. The surface can influence the reaction mechanism to produce new surface reaction products. The work, described here, shows the interaction of alpha-terpineol (major component of pine oil) with ozone and air on both glass and vinyl flooring. These results demonstrated emissions of oxygenated organic compounds as a result of reaction and that further investigations of this chemistry are required to accurately estimate indoor occupant exposures.     

Endotoxin,extracellular polysaccharides,and β(1‐3)‐glucan concentrations in dust and their determinants in four European birth cohorts: results from the HITEA project

Early‐life exposure to microbial agents may play a protective role in asthma and allergies development. Geographical differences in the prevalence of these diseases exist, but the differences in early‐life indoor microbial agent levels and their determinants have been hardly studied. We aimed to describe the early‐life levels of endotoxin, extracellular polysaccharides (EPS), and β(1‐3)‐glucans in living room dust of four geographically spread European birth cohorts (LISA in Germany, PIAMA in the Netherlands, INMA in Spain, and LUKAS2 in Finland) and to assess their determinants. A total of 1572 dust samples from living rooms of participants were analyzed for endotoxin, Penicillium/Aspergillus EPS, and β(1‐3)‐glucans. Information on potential determinants was obtained through questionnaires. Concentrations of endotoxin, EPS, and β(1‐3)‐glucans were different across cohorts. Concentrations of endotoxin and EPS were respectively lower and higher in INMA than in other cohorts, while glucans were higher in LUKAS2. Season of sampling, dog ownership, dampness, and the number of people living at home were significantly associated with concentrations of at least one microbial agent, with heterogeneity of effect estimates of the determinants across cohorts. In conclusion, both early‐life microbial exposure levels and exposure determinants differ across cohorts derived from diverse European countries.     

Fungal extracellular polysaccharides, beta (1-->3)-glucans and culturable fungi in repeated sampling of house dust

Fungal exposure inside homes has been associated with adverse respiratory symptoms in children and adults. While fungal assessment has traditionally relied upon questionnaires, fungal growth on culture plates and spore counts, new immunoassays for extracellular polysaccharides (EPS) and beta (1-->3)-glucans have enabled quantitation of fungal agents in house dust in a more timely and cost-effective manner, possibly providing a better measure of fungal exposure. We investigated associations among measurements of EPS, beta (1-->3)-glucans and culturable fungi obtained from 23 Dutch homes. From each home, dust samples were vacuumed from the living room floor twice during the Fall, Winter and Spring seasons for a total of six collections (every 6 weeks from October 1997 to May 1998). Samples were sieved and fine dust was analyzed for EPS from Aspergillus and Penicillium spp. combined, beta (1-->3)-glucans and culturable fungi. EPS was positively associated with glucan; an increase from the 25th to the 75th percentile of glucan concentration was associated with a 1.6-fold increase in EPS concentration (95% CI = 1.3 to 2.0; p < 0.01). The most significant variables associated with EPS and glucan concentrations were the surface type that was vacuumed and the concentration of total culturable fungi (in colony forming units (CFU)/g dust), with an increase in CFU/g from the 25th to the 75th percentile associated with a 1.3 (1.1-1.6)-fold increase in glucan and a 1.7 (1.3-2.2)-fold increase in EPS concentrations. In addition, the within-home variation of EPS levels were smaller than those between homes (25,646 U/g vs. 50,635 U/g), whereas the variation of glucan levels was similar within and between homes (1,300 vs. 1,205 micrograms/g). These positive associations suggest that house dust concentrations of beta (1-->3)-glucan, and particularly those of EPS, are good markers for the overall levels of fungal concentrations in floor dust which is a surrogate for estimating airborne fungal exposure.     

Low ratio of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol-glucuronides (NNAL-Gluc)/free NNAL increases urothelial carcinoma risk

Cigarette smoking is the most important risk factor for bladder cancer. The compound 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and its metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) are viewed as biomarkers for cigarette smoking exposure. Therefore, we wanted to explore the effects of these urinary metabolites on urothelial carcinoma (UC) risk. We recruited 127 pairs of UC cases and matched healthy participants for a hospital-based case-control study. Participants completed questionnaires of medical and social information, including smoking history, and provided 50 mL urine samples. Urine samples were analyzed for free NNAL and NNAL-Gluc using the liquid chromatography-tandem mass spectrometry method. Nonparametric analysis and multivariate logistic regression were applied to compare the differences in NNK-related metabolites between UC cases and controls, and to estimate the UC risk associated with certain risk factors. Overall, controls with higher cumulative cigarette smoking exposure had higher total NNAL, free NNAL and NNAL-Gluc. In addition, a decreased NNAL-Gluc/free NNAL ratio corresponded to a significantly increased UC risk. The association between the NNAL-Gluc/free NNAL ratio and UC risk was significant in a dose-response manner. Furthermore, cumulative cigarette smoking exposure was found to interact significantly with low NNAL-Gluc/free NNAL ratio to affect UC risk in this study. This is the first study to conclude that the metabolic products of total NNAL, free NNAL and NNAL-Gluc might be measured as biomarkers of cigarette smoking exposure. Furthermore, the NNAL-Gluc/free NNAL ratio was a better biomarker to evaluate UC risk than total NNAL.     

Dampness in buildings and health. Nordic interdisciplinary review of the scientific evidence on associations between exposure to "dampness" in buildings and health effects (NORDDAMP)

Several epidemiological investigations concerning indoor environments have indicated that "dampness" in buildings is associated to health effects such as respiratory symptoms, asthma and allergy. The aim of the present interdisciplinary review is to evaluate this association as shown in the epidemiological literature. A literature search identified 590 peer-reviewed articles of which 61 have been the foundation for this review. The review shows that "dampness" in buildings appears to increase the risk for health effects in the airways, such as cough, wheeze and asthma. Relative risks are in the range of OR 1.4-2.2. There also seems to be an association between "dampness" and other symptoms such as tiredness, headache and airways infections. It is concluded that the evidence for a causal association between "dampness" and health effects is strong. However, the mechanisms are unknown. Several definitions of dampness have been used in the studies, but all seems to be associated with health problems. Sensitisation to mites may be one but obviously not the only mechanism. Even if the mechanisms are unknown, there is sufficient evidence to take preventive measures against dampness in buildings.     

Comparison of various revised k–ε models and LES applied to flow around a high-rise building model with 1:1:2 shape placed within the surface boundary layer

This paper compares computational fluid dynamics (CFD) results using various revised k–ε models and large eddy simulation (LES) applied to flow around a high-rise building model with 1:1:2 shape placed within the surface boundary layer. The first part of the paper examines the accuracy of various revised k–ε models, i.e. LK model, MMK model and Durbin's revised k–ε model, by comparing their results with experimental data. Among the computations using various revised k–ε models compared here, Durbin's revised k–ε model shows the best agreement with the experiment. The reason for the good performance of Durbin's model is discussed on the basis of ‘Realizability’ of predicted results. The second part of the paper describes the computations based on LES with and without inflow turbulence applied to the same flowfield. The results are compared with those of the experiments and Durbin's k–ε model in order to clarify the effect of velocity fluctuations on prediction accuracy of time-averaged velocity fields around the building. Special attention is paid to prediction accuracy for reproducing flow behind a building. The LES results with inflow turbulence show generally good agreement with experimental results in terms of the distributions of velocity and turbulence energy in this region. This improvement is mainly due to the fact that the periodic velocity fluctuation behind the building is well reproduced in LES.     

Bacteria in a water‐damaged building: associations of actinomycetes and non‐tuberculous mycobacteria with respiratory health in occupants

We examined microbial correlates of health outcomes in building occupants with a sarcoidosis cluster and excess asthma. We offered employees a questionnaire and pulmonary function testing and collected floor dust and liquid/sludge from drain tubing traps of heat pumps that were analyzed for various microbial agents. Forty‐nine percent of participants reported any symptom reflecting possible granulomatous disease (shortness of breath on exertion, flu‐like achiness, or fever and chills) weekly in the last 4 weeks. In multivariate regressions, thermophilic actinomycetes (median = 529 CFU/m²) in dust were associated with FEV₁/FVC [coefficient = ?2.8 per interquartile range change, P = 0.02], percent predicted FEF_25–75% (coefficient = ?12.9, P = 0.01), and any granulomatous disease‐like symptom [odds ratio (OR) = 3.1, 95% confidence interval (CI) = 1.45?6.73]. Mycobacteria (median = 658 CFU/m²) were positively associated with asthma symptoms (OR = 1.5, 95% CI = 0.97?2.43). Composite score (median = 11.5) of total bacteria from heat pumps was negatively associated with asthma (0.8, 0.71?1.00) and positively associated with FEV₁/FVC (coefficient = 0.44, P = 0.095). Endotoxin (median score = 12.0) was negatively associated with two or more granulomatous disease‐like symptoms (OR = 0.8, 95% CI = 0.67?0.98) and asthma (0.8, 0.67?0.96). Fungi or (1→3)‐β‐D‐glucan in dust or heat pump traps was not associated with any health outcomes. Thermophilic actinomycetes and non‐tuberculous mycobacteria may have played a role in the occupants' respiratory outcomes in this water‐damaged building.     

Classroom ventilation and indoor air quality—results from the FRESH intervention study

Inadequate ventilation of classrooms may lead to increased concentrations of pollutants generated indoors in schools. The FRESH study, on the effects of increased classroom ventilation on indoor air quality, was performed in 18 naturally ventilated classrooms of 17 primary schools in the Netherlands during the heating seasons of 2010–2012. In 12 classrooms, ventilation was increased to targeted CO₂ concentrations of 800 or 1200 ppm, using a temporary CO₂ controlled mechanical ventilation system. Six classrooms were included as controls. In each classroom, data on endotoxin, β(1,3)‐glucans, and particles with diameters of <10 μm (PM₁₀) and <2.5 μm (PM_2.5) and nitrogen dioxide (NO₂) were collected during three consecutive weeks. Associations between the intervention and these measured indoor air pollution levels were assessed using mixed models, with random classroom effects. The intervention lowered endotoxin and β(1,3)‐glucan levels and PM₁₀ concentrations significantly. PM₁₀ for instance was reduced by 25 μg/m³ (95% confidence interval 13–38 μg/m³) from 54 μg/m³ at maximum ventilation rate. No significant differences were found between the two ventilation settings. Concentrations of PM_2.5 and NO₂ were not affected by the intervention. Our results provide evidence that increasing classroom ventilation is effective in decreasing the concentrations of some indoor‐generated pollutants.     

'EUROPART'. Airborne particles in the indoor environment. A European interdisciplinary review of scientific evidence on associations between exposure to particles in buildings and health effects

The relevance of particle mass, surface area or number concentration as risk indicators for health effects in non-industrial buildings has been assessed by a European interdisciplinary group of researchers (called EUROPART) by reviewing papers identified in Medline, Toxline, and OSH. Studies dealing with dermal effects or cancer or specifically addressing environmental tobacco smoke, house dust-mite, cockroach or animal allergens, microorganisms and pesticides were excluded. A total of 70 papers were reviewed, and eight were identified for the final review: Five experimental studies involving mainly healthy subjects, two cross-sectional office studies and one longitudinal study among elderly on cardiovascular effects. From most studies, no definite conclusions could be drawn. Overall, the group concluded that there is inadequate scientific evidence that airborne, indoor particulate mass or number concentrations can be used as generally applicable risk indicators of health effects in non-industrial buildings and consequently that there is inadequate scientific evidence for establishing limit values or guidelines for particulate mass or number concentrations.     

A coupled photocatalytic-biological process for degradation of 1-amino-8-naphthol-3, 6-disulfonic acid (H-acid)

 There has been growing emphasis on the development of coupled treatment systems (e.g., advanced oxidation–biological) for treating poorly biodegradable wastewater. An attempt has been made in the present study to couple photocatalytic (TiO₂/UV) pretreatment with conventional activated sludge process to achieve improvement in the biodegradation of H-acid. The combination of titanium dioxide and UV light has been known to generate strong oxidants that degrade several organic pollutants into carbon dioxide via the formation of some intermediates. The intermediates formed may undergo biodegradation readily. Accordingly, photodegradation experiments were carried out initially at an optimized TiO₂ dose and the minimum pretreatment time required for transforming H-acid was identified. For this purpose, UV–vis spectrophotometry and high-performance liquid chromatography (HPLC) were extensively used. Subsequently, it was attempted to biodegrade untreated and pretreated H-acid using activated sludge from the textile industry acclimatized to H-acid. It was found that photocatalytic pretreatment of H-acid for 30 min, during which period approximately 8–10% chemical oxygen demand (COD) removal occurred, can be coupled to second-stage biological treatment for achieving enhanced biodegradation of H-acid.     

Debris flow simulation 2D (DFS 2D): Numerical modelling of debris flows and calibration of friction parameters

Debris flows are rapid mass movements with a mixture of rock, soil and water. High-intensity rainfall events have triggered multiple debris flows around the globe, making it an important concern from the disaster management perspective. This study presents a numerical model called debris flow simulation 2D (DFS 2D) and applicability of the proposed model is investigated through the values of the model parameters used for the reproduction of an occurred debris flow at Yindongzi gully in China on 13 August 2010. The model can be used to simulate debris flows using three different rheologies and has a user-friendly interface for providing the inputs. Using DFS 2D, flow parameters can be estimated with respect to space and time. The values of the flow resistance parameters of model, dry-Coulomb and turbulent friction, were calibrated through the back analysis and the values obtained are 0.1 and 1000 m/s², respectively. Two new methods of calibration are proposed in this study, considering the cross-sectional area of flow and topographical changes induced by the debris flow. The proposed methods of calibration provide an effective solution to the cumulative errors induced by coarse-resolution digital elevation models (DEMs) in numerical modelling of debris flows. The statistical indices such as Willmott's index of agreement, mean-absolute-error, and normalized-root-mean-square-error of the calibrated model are 0.5, 1.02 and 1.44, respectively. The comparison between simulated and observed values of topographic changes indicates that DFS 2D provides satisfactory results and can be used for dynamic modelling of debris flows.     

独立新风系统(DOAS)研究(1):综述

介绍了独立新风系统的概念、背景、组成、特点和历史及其与建筑物的环境安全性、绿色建筑评估体系的关系。指出这种系统能明显提高室内空气品质、人体舒适感，减少空调系统一次投资和运行费用。