Indoor mold levels and current asthma among school‐aged children in Saskatchewan,Canada

Current knowledge regarding the association between indoor mold exposures and asthma is still limited. The objective of this case–control study was to investigate the relationship between objectively measured indoor mold levels and current asthma among school‐aged children. Parents completed a questionnaire survey of health history and home environmental conditions. Asthma cases had a history of doctor‐diagnosed asthma or current wheeze without a cold in the past 12 months. Controls were age‐ and sex‐matched to cases. Vacuumed dust samples were collected from the child's indoor play area and mattress. Samples were assessed for mold levels and quantified in colony‐forming units (CFU). Sensitization to mold allergens was also determined by skin testing. Being a case was associated with family history of asthma, pet ownership, and mold allergy. Mold levels (CFU/m²) in the dust samples of children's mattress and play area floors were moderately correlated (r = 0.56; P < 0.05). High mold levels (≥30 000 CFU/m²) in dust samples from play [adjusted odds ratio (aOR) = 2.6; 95% CI: 1.03–6.43] and mattress (aOR) = 3.0; 95% CI: 1.11–8.00) areas were significantly associated with current asthma. In this study high levels of mold are a risk factor for asthma in children.     

Associations between ventilation and children’s asthma and allergy in naturally ventilated Chinese homes

Building ventilation is important for occupants’ health. There are few studies of associations between home ventilation and occupant's health in China. During 2013-2016, we measured ventilation in 399 homes in Tianjin and Cangzhou, China, and surveyed the health history of children. Ventilation rates were measured using mass balance of occupant generated CO₂. The associations of home ventilation with children's asthma and allergy were analyzed in different strata of time and space. A low bedroom ventilation at night was significantly associated with an increased proportion of rhinitis among children (rhinitis current, adjusted odds ratio (AOR): 1.59; 95% confidence interval (CI): 1.01-2.49; diagnosed rhinitis, AOR: 3.02 (1.16-7.89)). Our findings suggest a dose-response relationship between ventilation rate at night in children's bedrooms and rhinitis current. The night-time ventilation rate in bedrooms has a greater association with rhinitis than the whole home ventilation rate during daytime.     

Perceived indoor air quality in naturally ventilated primary schools in the UK: Impact of environmental variables and thermal sensation

Indoor air quality (IAQ) in classrooms has a significant impact on children's academic performance, health, and well-being; therefore, understanding children's perception of IAQ is vital. This study investigates how children's perception of IAQ is affected by environmental variables and thermal sensation. In total, 29 naturally ventilated classrooms in eight UK primary schools were selected and 805 children were surveyed during non-heating and heating seasons. Results show that air sensation votes (ASVs) are more correlated to CO₂ levels than to operative temperatures (T_op) during non-heating seasons and more correlated to T_op than CO₂ levels during heating seasons. The impact of T_op on ASVs decreases with an increase in CO₂ levels, and the effect of CO₂ levels on ASVs decreases with increase in T_op. The most favorable ASVs are given when children feel “cool” and have “as it is” preference. By keeping CO₂ < 1000 ppm and T_op within children's thermal comfort band, ASVs are improved by 43%. The study recommends that standards should consider the impact of both temperature and CO₂ levels on perceived IAQ. Perception of IAQ also affects children's overall comfort and tiredness levels; however, this influence is more significant on tiredness level than that on overall comfort level.     

Sources and dynamics of fluorescent particles in hospitals

Fluorescent particles can be markers of bioaerosols and are therefore relevant to nosocomial infections. To date, little research has focused on fluorescent particles in occupied indoor environments, particularly hospitals. In this study, we aimed to determine the spatial and temporal variation of fluorescent particles in two large hospitals in Brisbane, Australia (one for adults and one for children). We used an Ultraviolet Aerodynamic Particle Sizer (UVAPS) to identify fluorescent particle sources, as well as their contribution to total particle concentrations. We found that the average concentrations of both fluorescent and non‐fluorescent particles were higher in the adults’ hospital (0.06×10⁶ and 1.20×10⁶ particles/m³, respectively) than in the children's hospital (0.03×10⁶ and 0.33×10⁶ particles/m³, respectively) (P<.01). However, the proportion of fluorescent particles was higher in the children's hospital. Based on the concentration results and using activity diaries, we were able to identify sources of particle production within the two hospitals. We demonstrated that particles can be easily generated by a variety of everyday activities, which are potential sources of exposure to pathogens. Future studies to further investigate their role in nosocomial infection are warranted.     

Application of land use regression to regulatory air quality data in Japan

A land use regression (LUR) model has been used successfully for predicting traffic-related pollutants, although its application has been limited to Europe and North America. Therefore, we modeled traffic-related pollutants by LUR then examined whether LUR models could be constructed using a regulatory monitoring network in Shizuoka, Japan. We used the annual-mean nitrogen dioxide (NO₂) and suspended particulate matter (SPM) concentrations between April 2000 and March 2006 in the study area. SPM accounts for particulate matter with an aerodynamic diameter less than 8 μm (PM₈). Geographic variables that are considered to predict traffic-related pollutants were classified into four groups: road type, traffic intensity, land use, and physical component. Using geographical variables, we then constructed a model to predict the monitored levels of NO₂ and SPM. The mean concentrations of NO₂ and SPM were 35.75 μg/m³ (standard deviation of 11.28) and 28.67 μg/m³ (standard deviation of 4.73), respectively. The final regression model for the NO₂ concentration included five independent variables. R² for the NO₂ model was 0.54. On the other hand, the regression model for the SPM concentration included only one independent variable. R² for the SPM model was quite low (R² = 0.11). The present study showed that even if we used regulatory monitoring air quality data, we could estimate NO₂ moderately well. This result could encourage the wide use of LUR models in Asian countries.     

Effectiveness of portable HEPA air cleaners on reducing indoor endotoxin,PM10, and coarse particulate matter in an agricultural cohort of children with asthma: A randomized intervention trial

We conducted a randomized trial of portable HEPA air cleaners in the homes of children age 6–12 years with asthma in the Yakima Valley, Washington. All families received asthma education while intervention families also received two HEPA cleaners (child's bedroom, living room). We collected 14-day integrated samples of endotoxin in settled dust and PM₁₀ and PM_10-2.5 in the air of the children's bedrooms at baseline and one-year follow-up, and used linear regression to compare follow-up levels, adjusting for baseline. Seventy-one families (36 HEPA, 35 control) completed the study. Baseline geometric mean (GSD) endotoxin loadings were 1565 (6.3) EU/m² and 2110 (4.9) EU/m², respectively, in HEPA vs. control homes while PM₁₀ and PM_10-2.5 were 22.5 (1.9) μg/m³ and 9.5 (2.9) μg/m³, respectively, in HEPA homes, and 19.8 (1.8) μg/m³ and 7.7 (2.0) μg/m³, respectively, in control homes. At follow-up, HEPA families had 46% lower (95% CI, 31%–57%) PM₁₀ on average than control families, consistent with prior studies. In the best-fit heterogeneous slopes model, HEPA families had 49% (95% CI, 6%–110%) and 89% lower (95% CI, 28%–177%) PM_10-2.5 at follow-up, respectively, at 50th and 75th percentile baseline concentrations. Endotoxin loadings did not differ significantly at follow-up (4% lower, HEPA homes; 95% CI, −87% to 50%).     

Associations between selected allergens,phthalates, nicotine,polycyclic aromatic hydrocarbons,and bedroom ventilation and clinically confirmed asthma,rhinoconjunctivitis, and atopic dermatitis in preschool children

Previous studies, often using data from questionnaires, have reported associations between various characteristics of indoor environments and allergic disease. The aim of this study has been to investigate possible associations between objectively assessed indoor environmental factors and clinically confirmed asthma, rhinoconjunctivitis, and atopic dermatitis. The study is a cross‐sectional case–control study of 500 children aged 3–5 years from Odense, Denmark. The 200 cases had at least two parentally reported allergic diseases, while the 300 controls were randomly selected from 2835 participating families. A single physician conducted clinical examinations of all 500 children. Children from the initially random control group with clinically confirmed allergic disease were subsequently excluded from the control group and admitted in the case group, leaving 242 in the healthy control group. For most children, specific IgE's against various allergens were determined. In parallel, dust samples were collected and air change rates were measured in the children's bedrooms. The dust samples were analyzed for phthalate esters, polycyclic aromatic hydrocarbons (PAH), nicotine, and various allergens. Among children diagnosed with asthma, concentrations of nicotine were higher (P < 0.05) and cat allergens were lower (P < 0.05) compared with the healthy controls; air change rates were lower for those sensitized (specific IgE+) compared with those not sensitized (specific IgE?, P < 0.05); and dust mite allergens were higher for specific IgE+ cases compared with healthy controls (P < 0.05). When disease status was based solely on questionnaire responses (as opposed to physician diagnosis), significant associations were found between di(2‐ethylhexyl) phthalate (DEHP) and dog allergens in dust and current wheeze.     

Removal of leachate pollutants using flocculation method at simultaneous factors of optimum pH and Tacca leontopetaloides biopolymer flocculant (TBPF) dosage via face-centred central composite design

The effect of the interaction factor between pH and dosage is important in leachate wastewater treatment. This study aims to remove leachate pollutants such as turbidity, total suspended solid (TSS), chemical oxygen demand (COD) and colour using simultaneous factors of plant-based Tacca leontopetaloides biopolymer flocculant (TBPF) dosage and leachate pH. The flocculation process was carried out through jar test by applying the perikinetic theory and statical analysis (face-centred central composite design). The results found that the optimum leachate pH and TBPF dosage were pH 3 and 150 mg/L, respectively. The highest removal of leachate pollutants reached up to 69% with a second-order perikinetic model; R² = 0.9545 and k = 9 × 10⁻⁶ L/mg/min were obtained. Simultaneous interaction factors between leachate pH and TBPF dosage on turbidity and TSS removal were found significant and hence can be applied in the actual leachate wastewater treatment industry, particularly at the primary stage using the proposed model.     

Housing characteristics and indoor air quality in households of Alaska Native children with chronic lung conditions

Alaska Native children experience high rates of respiratory infections and conditions. Household crowding, indoor smoke, lack of piped water, and poverty have been associated with respiratory infections. We describe the baseline household characteristics of children with severe or chronic lung disease participating in a 2012–2015 indoor air study. We monitored indoor PM2.5, CO₂, relative humidity %, temperature, and VOCs and interviewed caregivers about children's respiratory symptoms. We evaluated the association between reported children's respiratory symptoms and indoor air quality indicators using multiple logistic regression analysis. Compared with general US households, study households were more likely overcrowded 73% (62%–82%) vs 3.2% (3.1%–3.3%); had higher woodstove use as primary heat source 16% (9%–25%) vs 2.1% (2.0%–2.2%); and higher proportion of children in a household with a smoker 49% (38%–60%) vs 26.2% (25.5%–26.8%). Median PM2.5 was 33 μg/m³. Median CO₂ was 1401 ppm. VOCs were detectable in all homes. VOCs, smoker, primary wood heat, and PM2.5>25 μg/m³ were associated with higher risk for cough between colds; VOCs were associated with higher risk for wheeze between colds and asthma diagnosis. High indoor air pollutant levels were associated with respiratory symptoms in household children, likely related to overcrowding, poor ventilation, woodstove use, and tobacco smoke.     

Embeddedness of regions in European knowledge networks: a comparative analysis of inter-regional R&D collaborations,co-patents and co-publications

This paper investigates the embeddedness of European regions in different types of inter-regional knowledge networks, namely project-based R&D collaborations within the European framework programmes (FPs), co-patent networks and co-publication networks. Embeddedness refers to the network positioning of regions captured in terms of social network analytic (SNA) centrality measures. The objective is to estimate how region-internal and region-external factors influence network embeddedness in the distinct network types, in order to identify differences in their driving factors at the regional level. In our modelling approach, we apply advanced spatial econometric techniques by means of a mixed effects panel version of the spatial Durbin model (SDM) and introduce a set of variables accounting for a capacity specific, a relational as well as a spatial dimension in regional knowledge production activities. The results reveal conspicuous differences between the knowledge networks. Internal capacity- and technology-related aspects but also spatial spillover impacts from surrounding regions prove to be particularly important for centrality in the co-patent network. We also find significant—region-internal and region-external—impacts of general economic conditions on a region’s centrality in the FP network. However, we cannot observe substantial spillover effects of region-external factors on centrality in the co-publication network. Thus, the distinctive knowledge creation foci in each network seem to find expression in the network structure as well as its regional determinants.     

Effectiveness of portable HEPA air cleaners on reducing indoor PM2.5 and NH3 in an agricultural cohort of children with asthma: A randomized intervention trial

We conducted a randomized trial of portable HEPA air cleaners with pre-filters designed to also reduce NH₃ in non-smoking homes of children age 6-12 with asthma in Yakima Valley (Washington, USA). Participants were recruited through the Yakima Valley Farm Workers Clinic asthma education program. All participants received education on home triggers while intervention families additionally received two HEPA cleaners (child's sleeping area, main living area). Fourteen-day integrated samples of PM_2.5 and NH₃ were measured at baseline and one-year follow-up. We fit ANCOVA models to compare follow-up concentrations in HEPA vs control homes, adjusting for baseline concentrations. Seventy-one households (36 HEPA, 35 control) completed the study. Most were single-family homes, with electric heat and stove, A/C, dogs/cats, and mean (SD) 5.3 (1.8) occupants. In the sleeping area, baseline geometric mean (GSD) PM_2.5 was 10.7 (2.3) μg/m³ (HEPA) vs 11.2 (1.9) μg/m³ (control); in the living area, it was 12.5 (2.3) μg/m³ (HEPA) vs 13.6 (1.9) μg/m³ (control). Baseline sleeping area NH₃ was 62.4 (1.6) μg/m³ (HEPA) vs 65.2 (1.8) μg/m³ (control). At follow-up, HEPA families had 60% (95% CI, 41%-72%; p < .0001) and 42% (19%-58%; p = .002) lower sleeping and living area PM_2.5, respectively, consistent with prior studies. NH₃ reductions were not observed.     

Current wheeze,asthma, respiratory infections,and rhinitis among adults in relation to inspection data and indoor measurements in single‐family houses in Sweden—The BETSI study

In the Swedish Building Energy, Technical Status and Indoor environment study, a total of 1160 adults from 605 single‐family houses answered a questionnaire on respiratory health. Building inspectors investigated the homes and measured temperature, air humidity, air exchange rate, and wood moisture content (in attic and crawl space). Moisture load was calculated as the difference between indoor and outdoor absolute humidity. Totally, 7.3% were smokers, 8.7% had doctor’ diagnosed asthma, 11.2% current wheeze, and 9.5% current asthma symptoms. Totally, 50.3% had respiratory infections and 26.0% rhinitis. The mean air exchange rate was 0.36/h, and the mean moisture load 1.70 g/m³. Damp foundation (OR=1.79, 95% CI 1.16‐2.78) was positively associated while floor constructions with crawl space (OR=0.49, 95% CI 0.29‐0.84) was negatively associated with wheeze. Concrete slabs with overlying insulation (OR=2.21, 95% CI 1.24‐3.92) and brick façade (OR=1.71, 95% CI 1.07‐2.73) were associated with rhinitis. Moisture load was associated with respiratory infections (OR=1.21 per 1 g/m³, 95% CI 1.04‐1.40) and rhinitis (OR=1.36 per 1 g/m³, 95% CI 1.02‐1.83). Air exchange rate was associated with current asthma symptoms (OR=0.85 per 0.1/h, 95% CI 0.73‐0.99). Living in homes with damp foundation, concrete slabs with overlying insulation, brick façade, low ventilation flow, and high moisture load are risk factors for asthma, rhinitis, and respiratory infections.     

Particle concentrations and effectiveness of free-standing air filters in bedrooms of children with asthma in Detroit,Michigan

Asthma can be exacerbated by environmental factors including airborne particulate matter (PM) and environmental tobacco smoke (ETS). We report on a study designed to characterize PM levels and the effectiveness of filters on pollutant exposures of children with asthma. 126 households with an asthmatic child in Detroit, Michigan, were recruited and randomized into control or treatment groups. Both groups received asthma education; the latter also received a free-standing high efficiency air filter placed in the child’s bedroom. Information regarding the home, emission sources, and occupant activities was obtained using surveys administered to the child’s caregiver and a household inspection. Over a one week period, we measured PM, carbon dioxide (CO₂), environmental tobacco smoke (ETS) tracers, and air exchange rates (AERs). Filters were installed at midweek. Before filter installation, PM concentrations averaged 28 μg m⁻³, number concentrations averaged 70,777 and 1471 L⁻¹ in 0.3–1.0 and 1–5 μm size ranges, respectively, and the median CO₂ concentration was 1018 ppm. ETS tracers were detected in 23 of 38 homes where smoking was unrestricted and occupants included smokers and, when detected, PM concentrations were elevated by an average of 15 μg m⁻³. Filter use reduced PM concentrations by an average of 69–80%. Simulation models representing location conditions show that filter air flow, room volume and AERs are the key parameters affecting PM removal, however, filters can achieve substantial removal in even "worst" case applications. While PM levels in homes with asthmatic children can be high, levels can be dramatically reduced using filters.     

基于关联规则的儿童户外活动空间偏好 研究——以杭州三个社区公园为例

社区公园是儿童户外活动的重要承载空间。研究儿 童在社区公园的行为偏好及空间需求对增加儿童户外活动机 会、提升社区公园品质和促进环境公平具有重要意义。以杭州 市3个社区公园为研究对象,采用行为注记法获取儿童活动空 间分布特征,运用关联规则、核密度分析和多因素方差分析等 方法,研究儿童户外活动与社区公园空间和环境要素之间的关 系。研究发现,社区公园中儿童不同活动类型对空间的偏好度 存在显著差异：自然活动对特定空间的偏好度最高,主要集中 在有沙、水体和草坪的空间;功能活动和规则活动的空间偏好 度次之,多发生在器械区、广场等设施丰富或面积较大的场 地;休闲活动与大部分空间都具有关联性,分布较均衡。设 施、基底类型和植被覆盖等环境要素与儿童活动空间选择的关 联性较强。以此为基础,提出以儿童活动偏好为导向的社区公 园规划设计建议。     

Factors affecting variability in gaseous and particle microenvironmental air pollutant concentrations in Hong Kong primary and secondary schools

School-age children are particularly susceptible to exposure to air pollutants. To quantify factors affecting children's exposure at school, indoor and outdoor microenvironmental air pollutant concentrations were measured at 32 selected primary and secondary schools in Hong Kong. Real-time PM₁₀, PM_2.5, NO_2, and O₃ concentrations were measured in 76 classrooms and 23 non-classrooms. Potential explanatory factors related to building characteristics, ventilation practice, and occupant activities were measured or recorded. Their relationship with indoor measured concentrations was examined using mixed linear regression models. Ten factors were significantly associated with indoor microenvironmental concentrations, together accounting for 74%, 61%, 46%, and 38% of variations observed for PM_2.5, PM₁₀, O_3, and NO₂ microenvironmental concentrations, respectively. Outdoor concentration is the single largest predictor for indoor concentrations. Infiltrated outdoor air pollution contributes to 90%, 70%, 75%, and 50% of PM_2.5, PM₁₀, O_3, and NO₂ microenvironmental concentrations, respectively, in classrooms during school hours. Interventions to reduce indoor microenvironmental concentrations can be prioritized in reducing ambient air pollution and infiltration of outdoor pollution. Infiltration factors derived from linear regression models provide useful information on outdoor infiltration and help address the gap in generalizable parameter values that can be used to predict school microenvironmental concentrations.     

环境行为学视角下建成环境与儿童出行 影响机制研究

儿童依赖建成环境,并通过基本的出行行为满足其 自身发展的各项必要需求,其中儿童独立出行水平和出行方式 至关重要。随着中国城镇化持续推进,大城市边缘的小城镇在 迅速发展的同时,其建成环境也给儿童出行带来了一定安全隐 患,儿童出行安全问题值得关注。从环境行为学视角,结合既 往文献将儿童出行的影响因素归纳整理成个体、环境和其他因 素,随后对长沙市岳麓区莲花镇第五实验小学1 509名6~12 岁儿童及其家长展开实证调查和数据统计分析。结果显示： 儿童和家长对环境的安全感知会对儿童的出行决策产生较大 影响,机动车交通量及速度、交叉路口、道路复杂程度、步 道和自行车道及其基础设施设置、自然水体等是主要的显著 影响因素。据此,从空间布局、道路设计、交通设施配置和 社会环境方面提出了提升儿童出行安全水平的小城镇规划策 略建议。     

Prediction of blasting mean fragment size using support vector regression combined with five optimization algorithms

The main purpose of blasting operation is to produce desired and optimum mean size rock fragments. Smaller or fine fragments cause the loss of ore during loading and transportation, whereas large or coarser fragments need to be further processed, which enhances production cost. Therefore, accurate prediction of rock fragmentation is crucial in blasting operations. Mean fragment size (MFS) is a crucial index that measures the goodness of blasting designs. Over the past decades, various models have been proposed to evaluate and predict blasting fragmentation. Among these models, artificial intelligence (AI)-based models are becoming more popular due to their outstanding prediction results for multi-influential factors. In this study, support vector regression (SVR) techniques are adopted as the basic prediction tools, and five types of optimization algorithms, i.e. grid search (GS), grey wolf optimization (GWO), particle swarm optimization (PSO), genetic algorithm (GA) and salp swarm algorithm (SSA), are implemented to improve the prediction performance and optimize the hyper-parameters. The prediction model involves 19 influential factors that constitute a comprehensive blasting MFS evaluation system based on AI techniques. Among all the models, the GWO-v-SVR-based model shows the best comprehensive performance in predicting MFS in blasting operation. Three types of mathematical indices, i.e. mean square error (MSE), coefficient of determination (R²) and variance accounted for (VAF), are utilized for evaluating the performance of different prediction models. The R², MSE and VAF values for the training set are 0.8355, 0.00138 and 80.98, respectively, whereas 0.8353, 0.00348 and 82.41, respectively for the testing set. Finally, sensitivity analysis is performed to understand the influence of input parameters on MFS. It shows that the most sensitive factor in blasting MFS is the uniaxial compressive strength.     

Home and day‐care microenvironment exposure to Blomia tropicalis allergens and their associations with salivary eosinophilic cationic protein (ECP) among preschool children in Singapore

To date, exposure studies linking dust‐mite allergens with asthma and allergic morbidities have typically relied on sampling from representative locations in the home for exposure assessment. We determine the effects of differing microenvironments allergen exposures on asthma and asthma severity among 25 case and 31 control preschool children in Singapore. Blo t 5 allergen levels in various niches from the children's home and day‐care microenvironments as well as their Blo t 5 time‐weighted concentrations were determined. Eosinophilic cationic protein (ECP) levels from the children's saliva as markers for airway inflammation were obtained. Salivary ECP levels were higher in children with asthma than those without and the strength of association increased with higher salivary ECP levels. Although there was no relationship between time‐weighted Blo t 5 concentrations with salivary ECP levels among the controls, a positive statistically significant relationship was noted among cases, demonstrating the effects of cumulative exposure on asthma severity. Avoidance measures to reduce Blo t 5 allergen exposure should include all microenvironments that asthmatic children are exposed throughout the day.     

Spatiotemporally resolved black carbon concentration,schoolchildren's exposure and dose in Barcelona

At city level, personal monitoring is the best way to assess people's exposure. However, it is usually estimated from a few monitoring stations. Our aim was to determine the exposure to black carbon (BC) and BC dose for 45 schoolchildren with portable microaethalometers and to evaluate the relationship between personal monitoring and fixed stations at schools (indoor and outdoor) and in an urban background (UB) site. Personal BC concentra‐tions were 20% higher than in fixed stations at schools. Linear mixed‐effect models showed low R² between personal measurements and fixed stations at schools (R² ≤ 0.28), increasing to R² ≥ 0.70 if considering only periods when children were at schools. For the UB station, the respective R² were 0.18 and 0.45, indicating the importance of the distance to the monitoring station when assessing exposure. During the warm season, the fixed stations agreed better with personal measurements than during the cold one. Children spent 6% of their time on commuting but received 20% of their daily BC dose, due to co‐occurrence with road traffic rush hours and the close proximity to the source. Children received 37% of their daily‐integrated BC dose at school. Indoor environments (classroom and home) were responsible for the 56% BC dose.