Indoor Air

Published by Wiley
Online ISSN: 1600-0668
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Article
Unlabelled: There is convincing epidemiological evidence that 'dampness' in buildings is associated with respiratory effects. In order to identify health-relevant exposures in buildings with 'dampness', the study 'Dampness in Buildings and Health' (DBH) was initiated. In the first step of the study, cross-sectional data on home characteristics including 'dampness' problems, and symptoms in airway, nose, and skin among 10,851 children (1-6 years), were collected by means of a questionnaire to the parents. The prevalence of wheezing during the last 12 months was 18.9% and doctor-diagnosed asthma 5.4%. Rhinitis during the last 12 months was reported for 11.1% of the children and eczema during the last 12 months 18.7%. Gender, allergic symptoms among parents, and age of the child were associated with symptoms. Water leakage was reported in 17.8% of the buildings, condensation on windows in 14.3%, and detached flooring materials in 8.3%. Visible mould or damp spots were reported in only 1.5% of the buildings. The four 'dampness' indices were associated to higher prevalence of symptoms in both crude and adjusted analysis. Furthermore, it was found that the combination of water leakage in the home and PVC as flooring material in the child's or parent's bedroom was associated to higher prevalence of symptoms among children. However, the interpretation of this finding is unclear. The combination of water leakage and PVC may be a proxy, for example, reconstruction because of water damages. Practical implications: The study have showed that moisture-related problems in buildings are a risk factor for asthma and allergic symptoms among preschool children. The recommendation to the general public is to remediate damp buildings.
 
Article
Unlabelled: Experiments were carried out in a three-row, 21-seat section of a simulated aircraft cabin installed in a climate chamber to evaluate the extent to which passengers' perception of cabin air quality is affected by the operation of a gas-phase adsorption (GPA) purification unit. A total of 68 subjects, divided into four groups of 17 subjects took part in simulated 11-h flights. Each group experienced four conditions in balanced order, defined by two outside air supply rates (2.4 and 3.3 l/s per person), with and without the GPA purification unit installed in the recirculated air system, a total of 2992 subject-hours of exposure. During each flight the subjects completed questionnaires five times to provide subjective assessments of air quality, cabin environment, intensity of symptoms, and thermal comfort. Additionally, the subjects' visual acuity, finger temperature, skin dryness, and nasal peak flow were measured three times during each flight. Analysis of the subjective assessments showed that operating a GPA unit in the recirculated air provided consistent advantages with no apparent disadvantages. Practical implications: Operating a gas-phase adsorption (GPA) air purifier unit in the recirculated air in a simulated airplane cabin provided a clear and consistent advantage for passengers and crew that became increasingly apparent at longer flight times. This finding indicates that the expense of undertaking duly blinded field trials on revenue flights would be justified.
 
Article
Unlabelled: The effects of pet exposure and parental atopy on respiratory symptoms were investigated in 12,910 children residing in twelve districts of northeast China. Responses to a self-administered questionnaire completed by parents of children were used to ascertain children with persistent cough, persistent phlegm, doctor-diagnosed asthma, current asthma and current wheeze. Exposure to animals during pregnancy was positively associated with doctor-diagnosed asthma [adjusted odds ratio (ORs), 1.86; 95% confidence interval (CI) 1.35-2.57], current asthma (adjusted OR, 3.06; 95% CI, 1.95-4.81) and asthma-related symptoms. Pet exposure in the first year of life and currently having animals in household were also related to a significantly higher prevalence of doctor-diagnosed asthma and asthma-related symptoms in these children. Associations with respiratory symptoms strengthened with higher levels of animal exposure. Parental atopy increased the risk of asthma diagnosis (OR, 3.49; 95%CI, 2.84-4.30), current asthma (OR, 3.94; 95%CI, 2.81-5.54) and asthma-related symptoms. There was an interaction between parental atopy and pet exposure in persistent phlegm, but not in doctor-diagnosed asthma. We conclude that pet keeping and parental atopy increased the risk of respiratory symptoms in children. Parental atopy did modify the effect of pet exposure on persistent phlegm but not on doctor-diagnosed asthma. Practical implications: The relationship between exposure to animals and allergic respiratory diseases in childhood is controversial. Inconsistent with other cross-sectional studies mostly conducted in industrialized countries, our study indicates that exposure to animals may increase the occurrence of respiratory symptoms and diseases in children, and the associations with respiratory symptoms strengthened with higher levels of animal exposure parental atopy did modify the effect of pet exposure on persistent phlegm but not on doctor-diagnosed asthma. These findings support the view that measures should be taken to reduce animal exposure for children in China.
 
Article
Unlabelled: Indoor air is a dominant exposure for humans. More that half of the body's intake during a lifetime is air inhaled in the home. Thus, most illnesses related to environmental exposures stem from indoor air exposure. Indoor air was believed to be a major environmental factor for more than a hundred years, from the start of the hygienic revolution, around 1850, until outdoor environmental issues entered the scene, and became dominant around 1960. Main environmental issues today are outdoor air quality, energy use, and sustainable buildings, but not indoor air quality (IAQ). But, there is mounting evidence that exposure to IAQ is the cause of excessive morbidity and mortality. In developing regions indoor unvented burning of biomass for cooking is the cause of at least 2,000,000 deaths a year (mainly women and children), and in the developed world IAQ is a main cause of allergies, other hypersensitivity reactions, airway infections, and cancers. Cancer of the lungs is related to indoor radon and ETS exposure. Allergies, airway infections and sick building syndrome are associated with, e.g., "dampness", a low ventilation rate, and plasticizers. In the future more emphasis must be given to IAQ and health issues. Practical implications: Indoor air quality plays a major role with regard to public health. The main problems are in the developing countries with the indoor burning of biomass for cooking and heating. The solution is a stove with a chimney. In developed regions, good ventilation, getting rid of "dampness" problems, and adequate testing of new building materials would reduce morbidity and mortality.
 
Article
The purpose of this commentary is not to be critical specifically of the modeling of Chen et al. (2006). To the best of my knowledge, all prior modeling of indoor airborne respiratory disease transmission, including my own efforts (Fisk et al., 2005), have failed to account for some or all of the factors mentioned above. Rather, my purpose has been to point out need to develop and test substantially more sophisticated models of indoor respiratory disease transmission. The most effective strategy may be to develop semi-empirical models with structures based on first principles and model constants determined from analyses of empirical data.
 
Article
Abstract Abstract A cross-sectional study was carried out at Tianjin University campus, China, from February 21 to June 10, 2006, to survey the association between dampness in dorms, and allergy and airways infections among college students. The health and dampness conditions were self-reported by 3436 students living in 1511 dorm rooms located in 13 buildings on the campus. The buildings were selected according to their positions, construction periods and occupant densities. The symptoms involved wheezing, dry cough during night, rhinitis, eczema, cold/flu, ear inflammation, pneumonia and tuberculosis. The indoor moisture signs were mould/damp spots on walls, ceilings and floors; suspected or ever happened water damage; condensation on windowpane in winter and odours perceived by subjects themselves. There was a significant positive association between condensation and dry cough. Eczema was often reported in rooms with moisture problem. Dampness was a significant risk factor for common cold.
 
Article
Unlabelled: The population distributions of CO(2)-induced irritation sensitivity in the eyes (COI), tear film stability (break-up time, BUT), and epithelium damage (ED) and the relation of these to basic potential confounders were assessed in an age- and gender-stratified random sample of citizens in Aarhus County, Denmark. One hundred eighty-two non-allergic, non-smoking persons participated. A general health questionnaire and an indoor air questionnaire was filled out before the measurements. The BUT was non-normally distributed, as was COI at 16% CO(2) and single ED-scores. However, COI average for all levels was normally distributed and the total score for ED was only marginally deviating. BUT decreased, the threshold to CO(2) increased, and irritation intensity at CO(2) eye exposure decreased with increasing age. ED was increased among women. There were no internal relations between the three measures, but reduced BUT was seen among subjects rating high levels of exposure to dust, electrostatic fields, and dry air. ED decreased by perceived unpleasant odors and increased with experiences of high temperatures. CO(2) sensitivity increased by perceived draught, dry air, and noise exposure prior to measurements. Selection bias cannot be excluded and the results may therefore not be truly representative of the general population. However, the results may be used as reference data for future use of measurements of break-up time, epithelium defects, and CO(2) sensitivity of the eyes in the indoor air. Practical implications: The most direct implication is that results can be used as reference level for measurements in problem buildings and for individual measurements. The reference can also be used in research and the other results as basis for future hypotheses and for support of existing hypotheses.
 
Article
Abstract Modern, holistic indoor climate research started with the formation of an interdisciplinary ‘Indoor Climate Research Group’ in 1962 at the Institute of Hygiene, University of Aarhus, Denmark. After some years, other groups started similar research in Denmark and Sweden, and later – after the First International Indoor Air Symposium in Copenhagen 1978 – this research spread to many countries and today it is carried out globally by probably 2000 scientists. This paper recounts the history of Danish indoor climate research, focusing on the three decades from the early 1960s to the founding of the Indoor Air journal in 1991. The aim of this paper is to summarize what was learned in those earlier years and to call to the attention of researchers in this area the need of multidisciplinary research, mingling epidemiological fact-finding field studies with climate chamber studies and laboratory investigations. The review may be of interest to indoor climate researchers who want to know more about the early development of research on this multidisciplinary subject, as it emerged in a small country that undertook pioneering studies.
 
Article
Unlabelled: We examined the associations between biomarkers of allergy and inflammation, indoor environment in dwellings, and incidence and remission of symptoms included in the sick building syndrome (SBS) and changes in the home environment of 452 adults who were followed from 1992 to 2002 within the Uppsala part of the European Community Respiratory Health Survey (ECRHS). The 10-year incidence (onset) of general, mucosal, and dermal symptoms was 8.5%, 12.7%, and 6.8%, respectively. Dampness or indoor molds at baseline was a predictor of incidence of general (relative risk [RR] = 1.98), mucosal (RR = 2.28), and dermal symptoms (RR = 1.91). Women had higher incidence of general (RR = 1.74) and mucosal symptoms (RR = 1.71). Indoor painting increased the incidence of general symptoms (RR = 1.62). Bronchial responsiveness (BR), eosinophil counts in blood, total IgE and eosinophilic cationic protein (ECP) in serum at baseline were predictors of incidence of SBS. At follow-up, BR, total IgE, and C-reactive protein (CRP ) were associated with increased incidence of SBS. Moreover, subjects with doctor-diagnosed asthma at baseline had a higher incidence of general (RR = 1.65) and mucosal symptoms (RR = 1.97). In conclusion, female gender, dampness or indoor molds, indoor painting, and biomarkers of allergy and inflammation were associated with a higher incidence of SBS symptoms, in particular mucosal symptoms. Practical implications: The focus in Sweden on indoor environment issues over the last few decades has resulted in improvements in dwellings, and reduced tobacco smoking, which could be beneficial for public health. Reducing dampness and molds in the dwelling place is another important way of reducing occurrence of SBS symptoms in the general adult population. The association between the incidence of SBS symptoms and clinical biomarkers of allergy and inflammation suggests a common etiology between inflammatory diseases, including asthma, rhinitis, and SBS. Lastly, good agreement between self-reported and clinically diagnosed atopy indicates that questionnaire data on atopy can be used in epidemiological studies.
 
Article
Higher indoor concentrations of air pollutants due, in part, to lower ventilation rates are a potential cause of sick building syndrome (SBS) symptoms in office workers. The indoor carbon dioxide (CO2) concentration is an approximate surrogate for indoor concentrations of other occupant-generated pollutants and for ventilation rate per occupant. Using multivariate logistic regression (MLR) analyses, we evaluated the relationship between indoor CO2 concentrations and SBS symptoms in occupants from a probability sample of 41 U.S. office buildings. Two CO2 metrics were constructed: average workday indoor minus average outdoor CO2 (dCO2, range 6-418 ppm), and maximum indoor 1-h moving average CO2 minus outdoor CO2 concentrations (dCO2MAX). MLR analyses quantified dCO2/SBS symptom associations, adjusting for personal and environmental factors. A dose-response relationship (p < 0.05) with odds ratios per 100 ppm dCO2 ranging from 1.2 to 1.5 for sore throat, nose/sinus, tight chest, and wheezing was observed. The dCO2MAX/SBS regression results were similar.
 
Article
Unlabelled: 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.
 
Article
Abstract We report approximately 500 indoor–outdoor air exchange rate (AER) calculations based on measurements conducted in residences in three US metropolitan areas in 1999–2001: Elizabeth, New Jersey; Houston, Texas; and Los Angeles County, California. Overall, a median AER across these urban areas and seasons was 0.71 air changes per hour (ACH, or per hour; n = 509) while median AERs measured in California (n = 182), New Jersey (n = 163), and Texas (n = 164) were 0.87, 0.88, and 0.47 ACH, respectively. In Texas, the measured AERs were lower in the summer cooling season (median = 0.37 ACH) than in the winter heating season (median = 0.63 ACH), likely because of the reported use of room air conditioners as Houston is typically hot and humid during the summer. The measured AERs in California were higher in summer (median = 1.13 ACH) than in winter (median = 0.61 ACH). Because the summer cooling season in Los Angeles County is less humid than in New Jersey or Texas, natural ventilation through open windows and screened doors likely increased measured AER in California study homes. In New Jersey, AER were similar across heating and cooling seasons, although the median AER was relatively lower during the spring. Adequate ventilation or air exchange rate (AER) for an indoor environment is important for human health and comfort, and relevant to building design and energy conservation and efficiency considerations. However, residential AER data, especially measured by more accurate non-toxic tracer gas methodologies, are at present quite limited worldwide, and are insufficient to represent the variations across regions and seasons within and between homes, including apartments and condominiums in more densely populated urban areas. The present paper presents quantitative and qualitative data to characterize residential AERs in three US urban areas with different climate attributes.
 
Article
Unlabelled: Fourier transform infrared (FTIR) spectra of outdoor, indoor, and personal fine particulate matter (PM(2.5)) samples were collected during the Relationship of Indoor, Outdoor, and Personal Air (RIOPA) study. FTIR spectroscopy provides functional group information about the entire PM(2.5) sample without any chemical preparation. It is particularly important to characterizing the poorly understood organic fraction of PM(2.5). To our knowledge this is the first time that FTIR spectroscopy has been applied to a PM(2.5) exposure study. The results were used to chemically characterize indoor air and personal exposure. Sulfate was strongest in outdoor samples, which is consistent with the generally accepted understanding that sulfate is of outdoor origin. Absorbances attributed to soil dust were also seen in many outdoor and some indoor and personal samples. Inorganic nitrate absorbances were a common feature of many California and some New Jersey samples. Carbonyl absorbances showed substantial variation in strength, number of peaks, and wave number shift between samples, indicating variability in composition and sources. Absorbances attributed to aliphatic hydrocarbon and amide functional groups were enhanced in many personal and indoor samples, which suggested the influence of indoor sources in these homes. We speculate that meat cooking is one possible source of particulate amides. Practical implications: To our knowledge this is the first time that FTIR spectroscopy has been used to characterize the composition of indoor and personal PM(2.5). The presence of sulfate, nitrate, ammonium, soil dust and a number of organic functional groups are all detected in one analysis on filter samples without extraction or other sample preparation. Differences between indoor and outdoor spectra are used to identify spectral features due to indoor-generated PM(2.5). Particularly interesting are the much larger aliphatic absorbances, shifts in carbonyl absorbances, and occasional small amide absorbances found in indoor and personal spectra but rarely in outdoor spectra. These observations are important because organics make up a large portion of PM(2.5) mass and their composition and properties are poorly characterized. The properties and behavior of organic compounds in airborne particles are often predicted based on their functional group composition. This analysis begins the development of a better understanding of the functional group composition of indoor and personal PM(2.5) and how it differs from that of outdoor PM(2.5). Eventually this will lead to an improved understanding of the properties, behavior and effects of PM(2.5) of indoor and outdoor origin.
 
Article
Unlabelled: In 2005 through 2008, a small rural mountain valley community engaged in a woodstove changeout program to address concerns of poor ambient air quality. During this program, we assessed changes to indoor air quality before and after the introduction of a new, lower emission woodstove. We previously reported a >70% reduction in indoor PM(2.5) concentrations in homes following the installation of a new Environmental Protection Agency's-certified stove within the home. We report here on follow-up of the experiences in these and other homes over three winters of sample collection. In 21 homes, we compared pre-changeout PM(2.5) concentrations [mean (s.d.) = 45.0 (33.0) μg/m(3)] to multiple post-changeout measures of PM(2.5) concentrations using a DustTrak. The mean reduction (and 95% confidence interval) from pre-changeout to post-changeout was -18.5 μg/m(3) (-31.9, -5.2), adjusting for ambient PM(2.5) , ambient temperature, and other factors. Findings across homes and across years were highly variable, and a subset of homes did not experience a reduction in PM(2.5) following changeout. Reductions were also observed for organic carbon, elemental carbon, and levoglucosan, but increases were observed for dehydroabietic acid and abietic acid. Despite overall improvements in indoor air quality, the varied response across homes may be due to factors other than the introduction of a new woodstove. Practical implications: Biomass combustion is a common source of ambient PM(2.5) in many cold-climate communities. The replacement of older model woodstoves with newer technology woodstoves is a potential intervention strategy to improve air quality in these communities. In addition to ambient air, woodstove changeouts should improve residential indoor air quality. We present results from a multi-winter study to evaluate the efficacy of woodstove changeouts on improving indoor air quality. Reductions in indoor PM(2.5) were evident, but this observation was not consistent across all homes. These findings suggest that other factors beyond the introduction of an improved wood burning device are relevant to improving indoor air quality in wood burning homes.
 
Article
One of the reasons for the inadequate quality of indoor air arises from the poor articulation, appreciation and understanding of basic principles underlying the policies and actions related to indoor air quality. A WHO Working Group derived nine statements on rights to healthy indoor air. The discussions and statements are available as a WHO report. It informs the individuals and groups responsible for healthy indoor air about their rights and obligations, and empowers the general public by making people familiar with those rights. One year after their publication the statements have been adopted as the base for future regulation and guidance. The Board of Directors of the International Society of Indoor Air Quality (ISIAQ) and the participants of two international conferences endorse the use of the statements. No opposition to the statements have been registered. The statements have entered curricula of training courses and have been used in lawsuits.
 
Article
Abstract Laboratory measurements of the gaseous emission factors (EF) from two recent kerosene space heaters (wick and injector) with five different fuels have been conducted in an 8-m3 environmental chamber. The two heaters tested were found to emit mainly CO2, CO, NO, NO2, and some volatile organic compounds (VOCs). NO2 is continuously emitted during use, with an EF of 100–450 μg per g of consumed fuel. CO is normally emitted mainly during the first minutes of use (up to 3 mg/g). Formaldehyde and benzene EFs were quantified at 15 and 16 μg/g, respectively, for the wick heater. Some other VOCs, such as 1,3-butadiene, were detected with lower EFs. We demonstrated the unsuitability of a ‘biofuel’ containing fatty acid methyl esters for use with the wick heater, and that the accumulation of soot on the same heater, whatever the fuel, leads to a dramatic increase in the CO EF, up to 16 mg/g, which could be responsible for chronic and acute CO intoxications. Our results show that in spite of new technologies and emission standards for unvented kerosene space heaters, as well as for the fuels, the use of these heaters in indoor environments still leads to NOx levels in excess of current health recommendations. Whereas injection heaters generate more nitrogen oxides than wick heaters, prolonged use of the latter leads to a soot buildup, concomitant with high CO emissions, which could be responsible for acute and chronic intoxications. The use of a biofuel in a wick heater is also of concern. Maintenance of the heaters and adequate ventilation of the room during use of kerosene space heaters are therefore of prime importance to reduce personal exposure.
 
Article
Abstract In the present study, we modified an existing surface wipe sampling method for lead and other heavy metals to create a protocol to collect fungi in floor dust followed by real-time quantitative PCR (qPCR)-based detection. We desired minimal inconvenience for participants in residential indoor environmental quality and health studies. Accuracy, precision, and method detection limits (MDLs) were investigated. Overall, MDLs ranged from 0.6 to 25 cell/cm2 on sampled floors. Overall measurement precisions expressed as the coefficient of variation because of sample processing and qPCR ranged 6–63%. Median and maximum fungal concentrations in house dust in study homes in Visalia, Tulare County, California, were 110 and 2500 cell/cm2, respectively, with universal fungal primers (allergenic and nonallergenic species). The field study indicated samplings in multiple seasons were necessary to characterize representative whole-year fungal concentrations in residential microenvironments. This was because significant temporal variations were observed within study homes. Combined field and laboratory results suggested this modified new wipe sampling method, in conjunction with growth-independent qPCR, shows potential to improve human exposure and health studies for fungal pathogens and allergens in dust in homes of susceptible, vulnerable population subgroups. Fungi are ubiquitous in indoor and outdoor environments, and many fungi are known to cause allergic reactions and exacerbate asthma attacks. This study established—by modifying an existing—a wipe sampling method to collect fungi in floor dust followed by real-time quantitative PCR (qPCR)-based detection methodologies. Results from this combined laboratory and field assessment suggested the methodology’s potential to inform larger human exposure studies for fungal pathogens and allergens in house dust as well as epidemiologic studies of children with asthma and older adults with chronic respiratory diseases.
 
Article
Field studies demonstrate that there are substantial numbers of dissatisfied people in many buildings, among them those suffering from sick building syndrome (SBS) symptoms, even though existing standards and guidelines are met. The reason is that the requirements specified in these standards are rather low, allowing a substantial group of people to become dissatisfied and to be adversely affected. A paradigm shift from rather mediocre to excellent indoor environments is foreseen in the 21st century. Based on existing information and on new research results, five principles are suggested as elements behind a new philosophy of excellence: 1) better indoor air quality increases productivity and decreases SBS symptoms; 2) unnecessary indoor pollution sources should be avoided; 3) the air should be served cool and dry to the occupants; 4) "personalized air", i.e. a small amount of clean air, should be served gently, close to the breathing zone of each individual; and 5) individual control of the thermal environment should be provided. These principles of excellence are compatible with energy efficiency and sustainability.
 
Difference in mean ventilation rate between different building characteristics in single-family houses
Ventilation rate in single-family houses for case children with a doctor-diag- nosed disease compared with controls
Article
Abstract Abstract The aim of the study was to test the hypothesis that a low-ventilation rate in homes is associated with an increased prevalence of asthma and allergic symptoms among children. A total of 198 cases (with at least two of three symptoms: wheezing, rhinitis, eczema) and 202 healthy controls, living in 390 homes, were examined by physicians. Ventilation rates were measured by a passive tracer gas method, and inspections were carried out in the homes. About 60% of the multi-family houses and about 80% of the single-family houses did not fulfill the minimum requirement regarding ventilation rate in the Swedish building code (0.5 air changes per hour, ach). Cases had significantly lower ventilation rates than controls and a dose–response relationship was indicated.
 
Article
Abstract Abstract This study is performed as a part of research that examines the emission and diffusion characteristics of volatile organic compounds (VOCs) from indoor building materials. In this paper, the flow field and the emission field of VOCs from the surface of building materials in a Field and Laboratory Emission Cell (FLEC) cavity are examined by 3D Computational Fluid Dynamics (CFD) analysis. The flow field within the FLEC cavity is laminar. With a total flow of 250 ml/min, the air velocity near the test material surface ranges from 0.1 to 4.5 cm/s. Three types of emission from building materials are studied here: (i) emission phenomena controlled by internal diffusion, (ii) emission phenomena controlled by external diffusion, and (iii) emission phenomena controlled by mixed diffusion (internal + external diffusion). In the case of internal diffusion material, with respect to the concentration distribution in the cavity, the local VOC emission rate becomes uniform and the FLEC works well. However, in the case of evaporation type (external diffusion) material, or mixed type materials (internal + external diffusion) when the resistance to transporting VOCs in the material is small, the FLEC is not suitable for emission testing because of the thin FLEC cavity. In this case, the mean emission rate is restricted to a small value, since the VOC concentration in the cavity rises to the same value as the surface concentration through molecular diffusion within the thin cavity, and the concentration gradient normal to the surface becomes small. The diffusion field and emission rate depend on the cavity concentration and on the Loading Factor. That is, when the testing material surface in the cavity is partially sealed to decrease the Loading Factor, the emission rate become higher with the decrease in the exposed area of the testing material.
 
Article
Abstract Abstract The concentrations of cat (Fel d1) and dust-mite (Der f1 and Der p1) allergens were measured in 92 large office buildings in the US Environmental Protection Agency's Building Assessment Survey and Evaluation (BASE) Study (251 dust samples; one to four samples per building). Fel d1 was detected in almost all buildings and samples (91 buildings, 99%; 235 samples, 94%; range: <0.01–19 μg/g; median: 0.3 μg/g). Cat allergen exceeded 1 μg/g (a lower symptom threshold) in 56 samples (22%) from 45 buildings, but exceeded 8 μg/g (a sensitization threshold) in only two samples (1%) from two buildings. Der f1 or Der p1 was found in approximately half of all buildings and samples (63 and 70% of buildings; 45 and 51% of samples; range: <0.01–53 μg/g and <0.01–25 μg/g; median: <0.02 and 0.03 μg/g, respectively). Mite allergen exceeded 2 μg/g (a sensitization threshold) in seven samples (3%) from five buildings and exceeded 10 μg/g (a symptom threshold) in three samples (1%) from three buildings. Fel d1 concentration was significantly higher in samples collected in summer (June to September, 48 buildings), but cat allergen was not correlated with either mite allergen. Der f1, but not Der p1, concentration tended to be higher in samples collected in winter (December to April, 44 buildings), and the two mite allergens were significantly correlated only in winter. Cat and mite allergens were detected in 78% of representative US office buildings, but the concentrations seldom exceeded levels associated with sensitization or symptom provocation.
 
Article
The in vitro potency of house dust to induce cytokine response in A549 lung epithelial cells was studied. Dusts collected from carpet, bed, shelf and floor of a villa and an apartment by vacuuming were found to trigger the production of interleukin-8 (IL-8) and interleukin-6 (IL-6) in a dose-dependent manner, and the interleukin production was several-fold higher than of swine dust (used as a positive control). The IL-8 and IL-6 production of pure Escherichia coli lipopolysaccharide was significantly lower than of the dusts and a peptidoglycan-polysaccharide complex did not show any stimulatory effect at all. The lipopolysaccharide and peptidoglycan contents of the samples were determined by gas chromatography-tandem mass spectrometry analysis of, respectively, 3-hydroxy fatty acids and muramic acid; in addition, ergosterol was monitored for fungal biomass. The inflammatory properties of house dust upon inhalation may be reflected in its high potency to induce cytokine response in lung epithelial cells.
 
Article
Limited evidence associates inadequate classroom ventilation rates (VRs) with increased illness absence (IA). We investigated relationships between VRs and IA in California elementary schools over two school years in 162 3(rd) -5(th) grade classrooms in 28 schools in three school districts: South Coast (SC), Bay Area (BA), and Central Valley (CV). We estimated relationships between daily IA and VR (estimated from real-time carbon dioxide) in zero-inflated negative binomial models. We also compared IA benefits and energy costs of increased VRs. All school districts had median VRs below the 7.1 L/sec-person California standard. For each additional 1 L/sec-person of VR, IA was reduced significantly (p<0.05) in models for combined districts (-1.6%) and for SC (-1.2%), and non-significantly for districts providing less data: BA (-1.5%) and CV (-1.0%). Assuming associations were causal and generalizable, increasing classroom VRs from the California average (4 L/sec-person) to the State standard would decrease IA by 3.4%, increase attendance-linked funding to schools by $33 million annually, and increase costs only $4 million. Further increasing VRs would provide additional benefits. These findings, while requiring confirmation, suggest that increasing classroom VRs above the State standard would substantially decrease illness absence and produce economic benefits. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.
 
Article
Abstract Abstract Although almost all epidemiological studies of smaller airborne particles only consider outdoor concentrations, people in Central Europe actually spend most of their time indoors. Yet indoor pollutants such as organic gases, allergens and dust are known to play a prominent role, often affecting human health more than outdoor ones. The aim of this study was to ascertain how the indoor particle size distributions of submicron and ultrafine particles correlate with the outdoor concentrations in the absence of significant indoor sources. A typical indoor particle size distribution pattern has one or two modes. In the absence of significant indoor activities such as smoking, cooking etc., outdoor particles were found to be a very important source of indoor particles. The study shows that in the absence of significant indoor sources, the number of indoor concentrations of particles in this size range are clearly lower than the outdoor concentrations. This difference is greater, the higher the number of outdoor concentrations. However, the drop in concentration is not uniform, with the decrease in concentration of smaller particles exceeding that of larger ones. By contrast, the findings with larger particle sizes (diameter > 1 μm) exhibit rather linear concentration decreases. The non-uniform drop in the number of concentrations from outdoors to indoors in our measurements considering smaller particles ( >0.01 μm) is accompanied by a shift of the concentration maxima to larger particle diameters.
 
Article
INTRODUCTION: Many studies report an association between outdoor ambient weather and health. Outdoor conditions may be a poor indicator of personal exposure because people spend most of their time indoors. Few studies have examined how indoor conditions relate to outdoor ambient weather. METHODS AND RESULTS: The average indoor temperature, apparent temperature, relative humidity (RH), and absolute humidity (AH) measured in 16 homes in Greater Boston, Massachusetts, from May 2011 - April 2012 was compared to measurements taken at Boston Logan airport. The relationship between indoor and outdoor temperatures is non-linear. At warmer outdoor temperatures, there is a strong correlation between indoor and outdoor temperature (Pearson correlation coefficient, r = 0.91, slope, β = 0.41), but at cooler temperatures, the association is weak (r = 0.40, β = 0.04). Results were similar for outdoor apparent temperature. The relationships were linear for RH and AH. The correlation for RH was modest (r = 0.55, β = 0.39). AH exhibited the strongest indoor-to-outdoor correlation (r = 0.96, β = 0.69). CONCLUSIONS: Indoor and outdoor temperatures correlate well only at warmer outdoor temperatures. Outdoor RH is a poor indicator of indoor RH, while indoor AH has a strong correlation with outdoor AH year-round. This article is protected by copyright. All rights reserved.
 
Article
Unlabelled: A transient model is developed to predict dermal absorption of gas-phase chemicals via direct air-to-skin-to-blood transport under non-steady-state conditions. It differs from published models in that it considers convective mass-transfer resistance in the boundary layer of air adjacent to the skin. Results calculated with this transient model are in good agreement with the limited experimental results that are available for comparison. The sensitivity of the modeled estimates to key parameters is examined. The model is then used to estimate air-to-skin-to-blood absorption of six phthalate esters for scenarios in which (A) a previously unexposed occupant encounters gas-phase phthalates in three different environments over a single 24-h period; (B) the same as 'A', but the pattern is repeated for seven consecutive days. In the 24-h scenario, the transient model predicts more phthalate absorbed into skin and less absorbed into blood than would a steady-state model. In the 7-day scenario, results calculated by the transient and steady-state models converge over a time period that varies between 3 and 4 days for all but the largest phthalate (DEHP). Dermal intake is comparable to or larger than inhalation intake for DEP, DiBP, DnBP, and BBzP in Scenario 'A' and for all six phthalates in Scenario 'B'. Practical implications: Dermal absorption from air has often been overlooked in exposure assessments. However, our transient model suggests that dermal intake of certain gas-phase phthalate esters is comparable to, or larger than, inhalation intake under commonly occurring indoor conditions. This may also be the case for other organic chemicals that have physicochemical properties that favor dermal absorption directly from air. Consequently, this pathway should be included in aggregate exposure and risk assessments. Furthermore, under conditions where the exposure concentrations are changing or there is insufficient time to achieve steady-state, the transient model presented in this study is more appropriate for estimating dermal absorption than is a steady-state model.
 
Article
Unlabelled: Two experiments were conducted to investigate the use of the co-sorption effect of a desiccant wheel for improving indoor air quality. One experiment was conducted in a climate chamber to investigate the co-sorption effect of a desiccant wheel on the chemical removal of indoor air pollutants; another experiment was conducted in an office room to investigate the resulting effect on perceived air quality. A dehumidifier with a silica-gel desiccant wheel was installed in the ventilation system of the test chamber and office room to treat the recirculation airflow. Human subjects, flooring materials and four pure chemicals (formaldehyde, ethanol, toluene and 1,2-dichloroethane) were used as air pollution sources. Proton-Transfer-Reaction--Mass Spectrometry (PTR-MS) and sensory subjects were used to characterize the effectiveness of chemical and sensory pollution removal of the desiccant wheel. The experiments revealed that all the measured VOCs were removed effectively by the desiccant wheel with an average efficiency of 94% or higher; more than 80% of the sensory pollution load was removed and the percentage dissatisfied with the air quality decreased from 70% to 20%. These results indicate that incorporating a regenerative desiccant wheel in a ventilation system is an efficient way of removing indoor VOCs. Practical implications: This study may lead to the development of new air cleaners and validates a new concept for the design of ventilation systems that can improve indoor air quality and reduce energy consumption.
 
Article
Unlabelled: This study focuses on the relationship between classroom ventilation rates and academic achievement. One hundred elementary schools of two school districts in the southwest United States were included in the study. Ventilation rates were estimated from fifth-grade classrooms (one per school) using CO(2) concentrations measured during occupied school days. In addition, standardized test scores and background data related to students in the classrooms studied were obtained from the districts. Of 100 classrooms, 87 had ventilation rates below recommended guidelines based on ASHRAE Standard 62 as of 2004. There is a linear association between classroom ventilation rates and students' academic achievement within the range of 0.9-7.1 l/s per person. For every unit (1 l/s per person) increase in the ventilation rate within that range, the proportion of students passing standardized test (i.e., scoring satisfactory or above) is expected to increase by 2.9% (95%CI 0.9-4.8%) for math and 2.7% (0.5-4.9%) for reading. The linear relationship observed may level off or change direction with higher ventilation rates, but given the limited number of observations, we were unable to test this hypothesis. A larger sample size is needed for estimating the effect of classroom ventilation rates higher than 7.1 l/s per person on academic achievement. Practical implications: The results of this study suggest that increasing the ventilation rates toward recommended guideline ventilation rates in classrooms should translate into improved academic achievement of students. More studies are needed to fully understand the relationships between ventilation rate, other indoor environmental quality parameters, and their effects on students' health and achievement. Achieving the recommended guidelines and pursuing better understanding of the underlying relationships would ultimately support both sustainable and productive school environments for students and personnel.
 
Article
The purpose of this study was to investigate the concentrations of volatile organic compounds (VOCs) in different indoor microenvironments of residential homes and hostels in an academic institute, in New Delhi, during March to May 2011. Eleven VOCs (aromatic and halogenated) were assessed. Sampling and analytical procedure were based on a National Institute for Occupational Safety and Health (NIOSH) standard method. The lifetime cancer and non-cancer risk were calculated for targeted VOCs using US Environmental Protection Agency guidelines. The mean concentrations of ∑ VOCs (sum of monitored VOCs) and individual VOC were found to be higher indoors as compared to outdoors at both types of premises. Indoor to outdoor (I/O) ratios of the targeted VOCs exceeded 1.0 suggesting the significant presence of indoor sources. Strong correlations between I/O concentrations of VOCs in the current study suggest the presence of common sources. Factor analysis (FA) was used for source evaluation separately at two premise types. The estimated lifetime cancer risks in the current study for all occupants at both premises exceeded 10(-6) . This article is protected by copyright. All rights reserved.
 
Article
The combined effects of noise and temperature on environmental perception and acceptability were studied on 18 lightly clothed subjects (0.6 clo), individually exposed for 2 h in a climatic chamber. Three homogeneous climatic conditions were chosen (air temperature at 18, 24 or 30 degrees C, air velocity =0.1 m/s). For each of them, three different noise levels were continuously maintained (35, 60, 75 dBA, recorded fan noise). The 18 subjects were divided into three groups and each group experienced only one single thermal condition, at each level of noise, during three different experimental sessions. Subjective answers about perception and comfort were obtained at t = 30 and 120 min. Main results indicate that acoustic perception decreases when thermal environment is far from thermoneutrality. Although the combined effects of noise and temperature did not influence the physiological data, our results show that whatever the ambient temperature, thermal unpleasantness is higher when noise level increases. Finally, equivalence between acoustic and thermal sensations is proposed for short-term exposure (1 degree C = 2.6 dBA) and for steady state (1 degrees C = 2.9 dBA). In conclusion, this study strongly suggests that interactions between environmental components do exist, right from perceptual level, and might explain some combined effects on cognitive performance.
 
Article
Export Date: 4 February 2013 , Source: Scopus
 
Article
The aim of this study was to evaluate the amount of dust in supply air ducts in recently installed ventilation systems. The samples for the determination of dust accumulation were collected from supply air ducts in 18 new buildings that have been constructed according to two different cleanliness control levels classified as category P1 (low oil residues and protected against contaminations) and category P2, as defined in the Classification of Indoor Climate, Construction and Building Materials. In the ducts installed according to the requirements of cleanliness category P1 the mean amount of accumulated dust was 0.9 g/m2 (0.4-2.9 g/m2), and in the ducts installed according to the cleanliness category P2 it was 2.3 g/m2 (1.2-4.9 g/m2). A significant difference was found in the mean amounts of dust between ducts of categories P1 and P2 (P < 0.008). The cleanliness control procedure in category P1 proved to be a useful and effective tool for preventing dust accumulation in new air ducts during the construction process. Additionally, the ducts without residual oil had lower amounts of accumulated dust indicating that the demand for oil free components in the cleanliness classification is reasonable.
 
Article
Abstract It has been reported previously that people who are acclimated to naturally ventilated (NV) environments respond to hot and warm environments differently than people who are acclimated to air-conditioned (AC) environments. However, it is not clear whether physiological acclimatization contributes to this discrepancy. To study whether living and working in NV or AC environments for long periods of time can lead to different types of physiological acclimatization, and whether physiological acclimatization has an important influence on people’s responses of thermal comfort, measurements of physiological reactions (including skin temperature, sweat rate, heart rate variability, and heat stress protein 70) and thermal comfort responses were conducted in a ‘heat shock’ environment (climate chamber) with 20 people (10 in the NV group and 10 in the AC group). The results showed that the NV group had a significantly stronger capacity for physiological regulation to the heat shock than the AC group. In other words, the NV group did not feel as hot and uncomfortable as the AC group did. These results strongly indicate that living and working in indoor thermal environments for long periods of time affects people’s physiological acclimatization. Also, it appears that long-term exposure to stable AC environments may weaken people’s thermal adaptability. This study examined the psychological and physiological differences of thermal adaptability of people used to air-conditioned environments and naturally ventilated environments. The results suggested that long-term exposure to stable air-conditioned environments may weaken people’s thermal adaptability. Therefore, it might be advantageous for people to spend less time in static air-conditioned environments; this is not only because of its possible deleterious impact on people’s physiological adaptability, but also because the air-conditioners’ high-energy consumption will contribute to the effects of global warming.
 
Article
Cork samples were exposed to different temperatures and volatile ingredients were analyzed using gas chromatography/mass spectrometry (GC/MS). Thermal treatment at 180 degrees C yielded considerable amounts of furfural and acetic acid. In accordance with previous investigations it was concluded that both compounds are produced under thermal stress from degradation of polyoses.
 
Article
Abstract Abstract A study was carried out to investigate the feasibility of achieving ultra low respirable suspended particulates (RSP) in commercial offices without major modification of existing ventilation systems by enhancing the particulates removal efficiency of existing central ventilation systems. Four types of filters which include pre-filters, cartridge filters, bag filters and high efficiency particulates air (HEPA) filters were tested in a commercial building in Causeway Bay. The results show that an RSP objective of <20 μg/m3 could be met by removing RSP from both the return air and outdoor air supply simultaneously. This level of performance is classed as ‘excellent’ by the Hong Kong Government, Environmental Protection Department. Filters with efficiency that exceed 80% placed both in the return air and outdoor air were sufficient to meet the objective. It is not necessary to install HEPA filters to achieve the ‘excellent’ class. The outdoor air filter has great influence on the steady state indoor RSP concentration while the effective cleaning rate is governed by the return air filter. Higher efficiency filters increased the static drop but the volume flow of the air fan was not affected significantly. The additional cost incurred was <5% of the existing operation cost.
 
Article
Air and dust samples were collected on two floors of an office building during a double-blind particle intervention study to examine spatial and temporal variability of airborne endotoxin over a period of weeks, and to characterize endotoxin activity and lipopolysaccharide (LPS) content in carpet and chair dust. Air samples were collected on multiple days within and across weeks. Dust samples were collected from carpets and chairs one day per week for three weeks. Endotoxin was measured using a Limulus assay. Dust samples were analyzed for LPS by determination of 3-hydroxy fatty acids (3-OHFAs) using gas chromatography-mass spectrometry. The geometric mean (geometric standard deviation) for 96 indoor air samples was 0.24 (1.6) EU/m3. Significant within-floor spatial variation of airborne endotoxin was found (P < 0.0001, n = 80). Temporal variability of airborne endotoxin was not significant across weeks. Mean (+/- SD) endotoxin levels in carpet dust (59 +/- 9.3 EU/mg dust, n = 12) and in chair dust (38 +/- 7.7 EU/mg dust, n = 10) were significantly different (P < 0.001). Carbon chain length-dependent differences in 3-OHFA levels by dust source and floor were found. Enhanced air filtration did not significantly affect airborne endotoxin (P = 0.62); however, total dust mass and total endotoxin in carpet dust samples increased significantly after enhanced surface cleaning (P < 0.01). These findings suggest that spatial variability, dust source, and surface cleaning may influence building occupant exposures to endotoxin.
 
Article
It has been suggested that certain building factors can be associated with specific exposures, such as dampness, chemical emissions and dust. The aim of the study was to examine the relationships between some selected building factors, on the one hand, and signs of inflammation or obstruction in the upper airways on the other. Acoustic rhinometry and nasal lavage were used in a field study among 234 school personnel in 12 randomly selected schools (participation rate 84%). Eosinophil cationic protein (ECP), lysozyme, albumin and myeloperoxidase (MPO) were analyzed in the lavage fluid. Building related factors selected for the study were: roof inclination, fundament, building construction, signs of water damage, floor material, building age, ceiling height, bookcases and plants in the classroom. Control was made for potential confounders. The results indicate a pattern of nasal responses: less patent noses and an inflammatory biomarker response could be related to flat roof and a concrete slab fundament, factors that are known risk factors for water leakage, building dampness and possibly microbial growth. A reduced nasal patency without an inflammatory biomarker response was related to factors associated with plasticizers and dust. Positive effects were observed for plants in the classroom and in older buildings.
 
Article
Abstract This study examined how the intelligibility of irrelevant speech, determined with the Speech Transmission Index (STI), affects demanding cognitive task performance. Experiment was carried out in a laboratory that resembled an open-plan office. Three speech conditions were tested corresponding to a private office (STI = 0.10), an acoustically excellent open office (STI = 0.35) and an acoustically poor open office (STI = 0.65). All conditions were presented at equal level, 48 dBA. The STI was adjusted by the relative levels of speech and masking sound. Thirty-seven students participated in the experiment that lasted for 4 h. All participants performed five tasks in each of the three speech conditions. Questionnaires were used to assess subjective perceptions of the speech conditions. Performance in the operation span task, the serial recall and the activation of prior knowledge from long-term memory were deteriorated in the speech condition with the highest speech intelligibility (STI = 0.65) in comparison with the other two conditions (STI = 0.10 and STI = 0.35). Unlike performance measures, questionnaire results showed consistent differences among all three speech conditions, i.e. subjective disturbance increased with ascending speech intelligibility. Thus, subjective comfort was disturbed more easily than performance. The results support the use of STI as an essential room acoustic design measure in open-plan offices. Reduction of speech intelligibility in office environments by proper acoustic design would be beneficial in terms of both work performance and subjective comfort. Proper acoustic design requires both the use of high acoustic absorption and an appropriate masking sound.
 
Article
Building designers, engineers and occupants often need to estimate the organic compounds' levels in buildings. In order to satisfy the requirement, a web-based database, named AFoDAS/AVODAS database system is developed. The database consists of six databases for managing indoor air organic compounds' levels and building's environmental conditions. The database includes the monitoring results of about 1422 homes. The database allows users to (1) input their monitoring results to the database; (2) browse, search and query the database by a single or combinations of criteria for various query parameters such as building category, ventilation system, environment category, and compound names; and (3) estimate the organic compounds' levels resulting from various buildings and environmental conditions. This paper describes the functionality, database structure and major features of the user interface system of the database.
 
Article
Abstract Abstract In this study the dominant filamentous actinobacteria occurring in water-damaged building materials were detected by culture and characterized by automated ribotyping and 16S rRNA gene sequencing. Fifty-two samples were taken from 20 water-damaged houses in four different countries. A total of 122 bacterial isolates were analyzed. Actinobacteria or thermoactinomycetes were present in 48% of the samples. The dominant genus was Streptomyces (58% of isolates), followed by Thermoactinomyces (23%), Laceyella (14%), Nocardiopsis (3%), Pseudonocardia (1%) and Saccharomonospora (1%). The most frequently detected species was the thermophilic Thermoactinomyces vulgaris (14 samples/4 countries). The most common streptomycetes were closely related to the heterogeneous species Streptomyces microflavus (7/2) or Streptomyces griseus (6/2). Automated ribotyping was a rapid tool for reliable characterization of these isolates. The spores of thermoactinomycetes and toxic substances of Nocardiopsis species and S. griseus may constitute a risk for human health.
 
Top-cited authors
Charles Weschler
  • Rutgers, The State University of New Jersey
Jan Sundell
  • Tsinghua University
Yuguo Li
  • The University of Hong Kong
Pawel Wargocki
  • Technical University of Denmark
Geo Clausen
  • Technical University of Denmark