Showing papers in "Indoor Air in 1998"
TL;DR: In this paper, the impact of temperature and humidity on the perception of air quality and odour intensity of air was investigated in a set of experiments with five building materials and five levels of air pollution in the range 18-28°C and 30-70%RH.
Abstract: Sensory responses to clean air and air polluted by five building materials under different combinations of temperature and humidity in the ranges 18-28°C and 30-70%RH were studied in the laboratory. A specially designed test system was built and a set of experiments was designed to observe separately the impact of temperature and humidity on the perception of air quality/odour intensity, and on the emission of pollutants from the materials. This paper reports on the impact on perception. The odour intensity of air did not change significantly with temperature and humidity; however, a strong and significant impact of temperature and humidity on the perception of air quality was found. The air was perceived as less acceptable with increasing temperature and humidity. This impact decreased with an increasing level of air pollution. Significant linear correlations were found between acceptability and enthalpy of the air at all pollution levels tested, and a linear model was established to describe the dependence of perceived air quality on temperature and humidity at different pollution levels.
507 citations
TL;DR: A practical approach to indoor air problems is discussed, based mainly on experience from studies using the standardized MM questionnaires, which can deal with the complex situation arising from multiple low-level exposures of physical and biological origin, psychosocial and socioeconomic factors and variations in susceptibility of the occupants.
Abstract: Complaints about discomfort and effects on health are commonly reported from homes, workplaces, schools and daycare centres in various countries. Despite difficulties in relating these problems to specific agents in the indoor environment, it is often possible in practice to initiate efficient remedial actions by using a strategy involving structured information from the occupants and various technical measurements. In this presentation, a practical approach to indoor air problems is discussed, based mainly on experience from studies using the standardized MM questionnaires. By using suitable reference values, one can deal with the complex situation arising from multiple low-level exposures of physical and biological origin, psychosocial and socioeconomic factors and variations in susceptibility of the occupants.
213 citations
TL;DR: In this article, the acceptability of clean air and air polluted by building materials was studied in climate chambers with different levels of air temperature and humidity in the ranges 18-28°C and 30-70% relative humidity (RH).
Abstract: Acceptability of clean air and air polluted by building materials was studied in climate chambers with different levels of air temperature and humidity in the ranges 18–28°C and 30-70% relative humidity (RH). The acceptability of the air quality immediately after entering a chamber and during the following 20-min whole-body exposure was assessed by 36 untrained subjects who maintained thermal neutrality by modifying their clothing. The results confirm the significant decrement of the acceptability with increasing temperature and humidity, as shown in a previous study with facial exposures. The odour intensity was found to be independent of temperature and humidity. A linear relation between acceptability and enthalpy of air was again observed by this experiment. No significant difference was observed between the immediate acceptability and the acceptability during the following 20-min exposure, i.e., no adaptation took place. Both the immediate assessment of acceptability and the assessments during the 20-min exposure were independent of the air temperature and humidity to which the subjects were exposed before entering the chamber. The results further indicate that a notable decrement of the ventilation requirement may be achieved by maintaining a moderate enthalpy of air in spaces.
202 citations
TL;DR: In this article, seven VOC exposure metrics were developed and their ability to predict self-reported SBS irritant symptoms of office workers was tested and evaluated in a multivariate logistic regression analysis model adjusted for other risk factors or confounders.
Abstract: Occupants of office buildings are exposed to low concentrations of complex mixtures of volatile organic compounds (VOCs) that encompass a number of chemical classes and a broad range of irritancies. “Sick building syndrome” (SBS) is suspected to be related to these exposures. Using data from 22 office areas in 12 California buildings, seven VOC exposure metrics were developed and their ability to predict self-reported SBS irritant symptoms of office workers was tested. The VOC metrics were each evaluated in a multivariate logistic regression analysis model adjusted for other risk factors or confounders. Total VOCs and most of the other metrics were not statistically significant predictors of symptoms in crude or adjusted analyses. Two metrics were developed using principal components (PC) analysis on subsets of the 39 VOCs. The Irritancy/PC metric was the most statistically significant predictor of adjusted irritant symptoms. The irritant potencies of individual compounds, highly correlated nature of indoor VOC mixtures, and probable presence of potent, but unmeasured, VOCs were variously factored into this metric. These results, which for the first time show a link between low level VOC exposures from specific types of indoor sources to SBS symptoms, require confirmation using data sets from other buildings.
135 citations
TL;DR: In this article, a three-dimensional drift-flux model for particle movements in turbulent airflows in buildings is presented, assuming the effect of particles on air turbulence is negligible due to low solid loadings and comparatively small particle settling velocities.
Abstract: A three-dimensional drift-flux model for particle movements in turbulent airflows in buildings is presented. The interaction between the carrier air and the particles has been treated as a one-way coupling, assuming the effect of particles on air turbulence is negligible due to low solid loadings and comparatively small particle settling velocities. Turbulence effects are modelled with a standard κ-ɛ model. Wall functions are applied at near-wall grid points. Aerosol measurements carried out under turbulent room flow conditions are used to validate the numerical calculations. Several particle size distributions are considered in the simulations. The model is then applied to mixed flow conditions in a room, as well as to homogeneous air supply conditions around a human body. The flow fields and particle distributions are analysed. Close to a standing person, the particle distribution pattern from a downstream point source is strongly dependent on the ventilation air supply rate. This has been confirmed by experiments reported in the literature.
130 citations
TL;DR: In this article, a random sample of 450 houses representing various decades was surveyed by trained civil engineers for signs of water leaks or condensation, and 80% of the houses, signs of current or previous moisture fault were observed.
Abstract: A random sample of 450 houses representing various decades was surveyed by trained civil engineers for signs of water leaks or condensation. In 80% of the houses, signs of current or previous moisture fault were observed. In most houses, the surveyors made at least two separate observations of moisture but the occupants missed one in every two of these signs of moisture damage. Part of the faults were caused by flaws in design or construction, and part were due to aging of materials. Approximately 55% of the Finnish houses (i.e., a total of nearly 500 000 houses), were assessed to be in need of repair or more thorough inspection. The observations were equally frequent in the houses of different age, but certain types of moisture damage were characteristic of certain types of buildings or constructional methods used in different eras. Roof geometry was a significant factor accounting for roof leakages. The majority of the faults could be repaired at reasonable cost.
113 citations
TL;DR: It is concluded that families with atopic individuals should wait until the child is at least two years old before getting a pet and pet allergens are present “everywhere”, as a result of people bringing allergens in their clothing, etc.
Abstract: Ten researchers from the Nordic countries have reviewed the literature on early exposure in childhood, to pets and the risk of sensitisation/allergy. A search of the literature resulted in identification of about 1200 articles, of which 89 were selected for further examination. The group concluded that all exposure to pets involves a risk of sensitisation. Exposure in infancy involves an increased risk (normally RR = 1–1,5) of sensitisation and to a lesser degree of the development of symptoms. The group also concluded that pet allergens are present “everywhere”, as a result of people bringing allergens in their clothing, etc. The group concluded as a recommendation, that families with atopic individuals should wait until the child is at least two years old before getting a pet.
64 citations
TL;DR: A more complete model for evaluating tuberculosis infection control methods in health-care settings is proposed and emissions of infectious droplet nuclei by contagious persons and air leakage rates from isolation rooms are outlined.
Abstract: Diverse control measures can be applied to reduce tuberculosis infection risk in health-care facilities. Selecting optimal controls requires methods for predicting the dependence of infections risk on underlying parameters. A common model for infection risk only explicitly accounts for control by ventilation. This paper proposes a more complete model for evaluating tuberculosis infection control methods in health-care settings. An infection risk parameter is defined as the probable number of infectious droplet nuclei inhaled by all susceptible persons from a single infectious person. Algebraic model equations are presented for two exposure cases. In one, the susceptible and infectious persons are together in a well-mixed indoor environment; in the socond, the infectious person is in respiratory isolation. Model equations are used to explore many common tuberculosis control measures: identification, isolation and treatment of tuberculosis cases; surgical masks and treatment booths applied at the source; environmental controls such as ventilation, air filtration, and ultraviolet germicidal irradiation; and respiratory protection for susceptible persons. Experimental data are limited or lacking on some key variables, such as emissions of infectious droplet nuclei by contagious persons and air leakage rates from isolation rooms. Methods are outlined for collecting additional data.
58 citations
53 citations
TL;DR: The authors found that moisture sources in the houses were a more significant factor in mold levels and dust mite antigen levels than relative humidity, indicating that much of the mold growth was in hidden locations.
Abstract: Fifty-nine houses in the small Canadian community of Wallaceburg, 39 with high levels of biologically active contaminants and 20 with low levels, were subjected to detailed field inspections: testing to determine house-operating parameters; monitoring of indoor environmental conditions; and simulating to predict the condensation formation potential under winter conditions. It was found that low air leakage and natural ventilation were not associated with higher levels of mold growth, as measured by ergosterol concentrations and airborne viable particulates. Analyses showed that moisture sources in the houses were a more significant factor in mold levels and dust mite antigen levels than relative humidity. Mold areas visible during inspection were not a good predictor of ergosterol concentrations in dust, indicating that much of the mold growth was in hidden locations.
50 citations
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.
TL;DR: In this article, an air-dilution system connected to the exhaust of a ventilated small-scale test chamber is proposed to determine the exposure-response relationship between concentration of the emission from a building product and human response.
Abstract: Building products have been shown to affect the perceived indoor air quality in buildings. Consequently, there is a need for characterizing the emissions from building products in sensory terms to evaluate their impact on the perceived air quality. Determining the exposure-response relationship between concentration of the emission from a building product and human response is recommended. A practical method is proposed based on an air-dilution system connected to the exhaust of a ventilated small-scale test chamber. The method was used to determine the exposure-response relationships for eight building products. For each building product, samples were placed in a test chamber. A typical room was used as a reference to calculate a building-realistic area-specific ventilation rate in the test chamber. A sensory panel assessed the immediate acceptability of polluted air at four different concentrations 3, 10 and 29 days after samples of the building products were placed in the test chambers. The exposure-response relationships show that the impact of dilution of polluted air on the perceived air quality varies between building products. For some building products it may only be possible in practice to improve the perceived air quality marginally by increasing dilution. The results of the present study suggest that for such building products, source control is recommended as the remedy for poor indoor air quality, rather than an increase of the ventilation rate.
TL;DR: In this article, the authors measured volatile organic compounds (VOCs) in the air of 51 renovated rooms in Schleswig-Holstein and identified the dominating substances in the 46/51 complaint cases were well-known substances such as alkylbenzenes or monoterpenes at high concentrations but also less common substances, i.e. those which have only recently been reported as indoor air contaminants, for example phenoxyethanol, 2-(2-butoxyethoxy)-ethylacetate (butyldiglycolacetate) or long
Abstract: Volatile organic compounds (VOCs) were measured in the air of 51 renovated rooms in Schleswig-Holstein. The buildings examined were of different types – private flats, schools, kindergartens, office buildings – the only common characteristic being that they had all been renovated within the last two years. Among the dominating substances in the 46/51 complaint cases were well-known substances such as alkylbenzenes or monoterpenes at high concentrations but also less common substances, i.e. those which have only recently been reported as indoor air contaminants, for example phenoxyethanol, 2-(2-butoxyethoxy)-ethylacetate (butyldiglycolacetate) or longifolene (Mohr, 1994) at remarkable concentrations. A tentative investigation was made to identify the simultaneous occurrences of the different substances, especially the uncommon ones with their potential sources, as well as health impairments. Finally, VOC emissions from two carpet glues, suspected during the investigations of playing a role as a potential source of the less common substances, were carefully measured under test chamber conditions. This additional laboratory experiment was made to verify the tendency shown in the field study that modern ecological building materials contain less volatile and less common substances but with increased indoor persistence, that could partially account for the increasing number of complaints in relation to the SBS phenomenon.
TL;DR: Mycotoxins are secondary metabolites produced by many species of fungi, such as Penicillium, Aspergillus, Fusarium and Stachybotrys, which are detected in building materials and dust samples and in buildings with mould problems.
Abstract: Mycotoxins are secondary metabolites produced by many species of fungi, such as Penicillium, Aspergillus, Fusarium and Stachybotrys. Mycotoxicosis can affect humans and animals after ingestion of mouldy, mycotoxin-contaminated food or feed. Recent years have seen increasing interest in inhalation exposure to mycotoxins in agricultural environments and in water-damaged buildings with mould problems. Inhalation exposure to mycotoxins can occur by inhalation of airborne mycotoxin-containing particles, such as fungal spores. There is evidence that inhalation exposure to aflatoxins can elevate cancer risk, and inhalation exposure to ochratoxins can cause kidney damage. In buildings with mould problems, trichothecene mycotoxins have been detected in building materials and dust samples. In these cases, residents have suffered from respiratory tract symptoms and irritation of eyes and skin.
TL;DR: The study showed that in older buildings with poor ventilation, a build-up of ISP, and elevated RSP levels, using higher performance carpet cleaning practices can reduce RSP to acceptable levels and can reduce SBS symptoms.
Abstract: Five floors of a 20-year old 6-story office building were investigated using an integrated step-by-step investigation strategy. This involved a walkthrough inspection, an occupant questionnaire, and targeted environmental monitoring of indoor air quality and comfort parameters. The initial questionnaire survey revealed a high occurrence of building-related symptoms. The walkthrough inspection and environmental monitoring identified deposits of surface dust (indoor surface pollution – ISP) on carpets and hard surfaces, and elevated levels of carbon dioxide and respirable suspended particulate matter (RSP) throughout the building. An intervention study (blinded to the occupants) was targeted at reducing ISP levels by replacing normal carpet cleaning practices with higher performance vacuum cleaners and improved cleaning practices. The intervention reduced ISP levels and significantly lowered RSP concentrations by approx. 80% from initial values and against control floors. A follow-up SBS questionnaire revealed significant reductions in all but two of the symptoms. The most significant reductions occurred with symptoms of eye irritation, throat irritation, dry unproductive cough, and nose irritation. The study showed that in older buildings with poor ventilation, a build-up of ISP, and elevated RSP levels, using higher performance carpet cleaning practices can reduce RSP to acceptable levels and can reduce SBS symptoms.
TL;DR: In this paper, the authors investigated the relation between cleaning and dust in the indoor environment and the measuring methods applied using different interventions, and found that a reduction in the dust concentration on the so-called easily accessible surfaces was observed.
Abstract: Insufficient cleaning may be a cause of the Sick Building Syndrome Various improvements in cleaning methods have been tested in order to clarify whether they reduced the concentration of airborne dust, and the concentration of dust on surfaces, or whether the concentration of different microbiological components in the dust was reduced The interventions were performed in an administration building, a school and a kindergarten Dust measurements were performed on one day every week for a period of 28 weeks, using different interventions The airborne dust concentration was measured by sampling on filters during the day The concentration of surface dust was measured by the BM-Dustdetector foil sampling method Dust samples were collected from the floors, after which analyses for different microbiological components were performed Sampling from surfaces and the floor were performed prior to cleaning in order to ascertain the levels to which the room occupants had been exposed One of the findings was a reduction in the dust concentration on the so-called easily accessible surfaces Correlations between surface dust and airborne dust were also found Furthermore, correlations between the measurements and other factors, such as activity during the day, and the climate, were obtained Important findings of the study were the observations made on the relations between cleaning and dust in the indoor environment and the measuring methods applied
TL;DR: In this article, a limited number of experiments have been conducted to investigate the influence of parameters such as the adsorption time, the desorption times, the concentration of the pollutants and the temperature, on the sorption.
Abstract: Sorption effects of a number of combinations of indoor materials and volatile organic compounds have been investigated. A limited number of experiments have been conducted to investigate the influence of parameters such as the adsorption time, the desorption time, the concentration of the pollutants and the temperature, on the sorption. Experiments were performed with vapours of single compounds and with mixtures of VOCs. All parameters have an influence on the sorption. A relatively quick screening method can be applied with mixtures of VOCs with a limited adsorption time and desorption time (6 h each). Air samples should be collected at the end of the adsorption time and during the desorption time. © Indoor Air (1998).
TL;DR: In this article, the vertical concentration profiles for various size fractions of airborne particulate matter have been measured in a nonsmoking indoor environment used mainly as a meeting point during coffee break (11.00 a.m.) and tea time (4.00 p.m.).
Abstract: Vertical concentration profiles for various size fractions of airborne particulate matter have been measured in a nonsmoking indoor environment used mainly as a meeting point during coffee break (11.00 a.m.) and tea time (4.00 p.m.). This monitoring exercise was carried out using a novel sampling system specifically designed for measuring concentration gradients of airborne particles (but which can be easily modified for gaseous pollutants) over the first three metres from ground. The results show substantial gradients in concentration, with the highest occurring at around 1.3 m height. A plausible explanation for the measured time series of concentration at different levels from ground, and the vertical distribution of concentration, is thought to be human movement and activity in the confined environment. The implications that the results of this experiment have for indoor air quality standards for airborne particulate matter are discussed.
TL;DR: A theoretical model is proposed, the Office Environment Model, to explain the relationship between office environment and health, and divides the office environment ontologically into physical and social, and the health outcomes into physiological and psychological.
Abstract: This paper examines the phenomenon sick building syndrome and related concepts, and proposes a theoretical model, the Office Environment Model, to explain the relationship between office environment and health. The sick building syndrome should be thought of as a figurative concept of everyday language, rather than as a single disease entity. This is because the phenomenon consists of several types of relations between different environmental determinants and health. Based on Popper's framework of three worlds, the model divides the office environment ontologically into physical and social, and the health outcomes into physiological and psychological. The outcome is further categorized into two dimensions: anatomic site (eyes, respiratory tract, skin, and central nervous system), and hypothesized underlying mechanism (mechanical irritation and inflammation, immunological reaction, toxicity, infection, and environmental psychological stress). The model stipulates the following types of causal relations. The physical environment causes physical and psychological effects via physiological and/or psychological processes. The social environment causes physical and psychological effects via psychological processes. The physical and social environment may have synergistic effects, and constitutional factors such as gender and atopy are additional determinants of the outcomes, as well as possible modifiers of the relations between environment and health. To understand the health effects of the office environment, it is necessary to focus separately on different determinant-outcome relations, bearing in mind that the different determinants affect human health concurrently and sometimes the effects may be synergistic.
TL;DR: In this article, a total of 140 homes in the Po River Delta area of North Italy (near Venice) were monitored during summer and winter to measure the concentration of nitrogen dioxide (NO2), and respirable suspended particulate matter (RSP, ≤ 2.5 μm).
Abstract: A total of 140 homes in the Po River Delta area of North Italy (near Venice) were monitored during summer and winter to measure the concentration of nitrogen dioxide (NO2), and respirable suspended particulate matter (RSP, ≤ 2.5 μm). In this paper, the findings on home characteristics, daily activity pattern of occupants, and residential indoor air quality are described. Our study confirms that people spend the greater part of their daily lives indoors (84%), especially at home (64%). The concentration of monitored pollutants was greater in winter than in summer. The highest levels of NO2 were found in the kitchens. Significantly higher indoor NO2 levels were found in the houses with gas-furnace heating and/or with gas water heater located inside the home. RSP was significantly higher in homes where tobacco smoking took place, and was significantly related to the number of cigarettes smoked. A significant relationship between NO2 indoor concentrations and RSP values in both seasons was found.
TL;DR: A theoretical model for correlating odor thresholds of volatile organic compounds (VOCs) with their simple physicochemical properties has been developed and suggests that acetates, alcohols and ketones probably bind to a common receptor site located in the hydrophobic interior of the lipid bi-layer membrane of the olfactory cilia.
Abstract: A theoretical model for correlating odor thresholds of volatile organic compounds (VOCs) with their simple physicochemical properties has been developed. The partition coefficient between octanol and water, and that between water and air were used to model the partition process of airborne chemicals into the biophase where the olfactory signal is transformed. Validation was performed by fitting data on odor thresholds and partition coefficients for acetates, alcohols, ketones and amines into the model. Quantitative structure-activity relationships (QSARs) for the four series were developed from the model. The results suggest that acetates, alcohols and ketones probably bind to a common receptor site located in the hydrophobic interior of the lipid bi-layer membrane of the olfactory cilia. Amines probably bind to a different receptor site located closer to the mucus layer. The results also suggest that odor thresholds of related VOCs which appear to share a common receptor site may be additive.
TL;DR: In this article, the authors evaluate the COMIS model for multizone air infiltration and pollutant transport in an airtight test house, the aim being to evaluate the calculation model COMIS for multi-zone air intake and pollution transport.
Abstract: This paper describes the measured and calculated results of airflow rates and pollutant concentration profiles in an airtight test house, the aim being to evaluate the calculation model COMIS for multizone air infiltration and pollutant transport. Firstly, the leakage areas of internal doors, exterior walls and windows were measured by the fan pressurization method. Secondly, two measurements were carried out, assuming that the test house consisted of ten zones. The concentrations and injection rate of SF6 were measured in order to determine the airflow rates by a system identification method. The boundary conditions, such as indoor and outdoor temperatures, wind speed and direction, and wind pressures were also recorded in situ and saved simultaneously on diskettes, using a computerized data acquisition system. Thirdly, the measured boundary data and leakage characteristics were used as input in the simulation of airflow using COMIS; initial concentrations, injection rate, along with the previous data were used for simulating pollutant transport, assuming tracer gas SF6 as a pollutant. Lastly, the comparisons between measurement and simulation results of airflow rates and pollutant concentrations were carried out by linear regression analysis. The correlation coefficient between the measured and calculated air change rates was 0.72, and that for pollutant concentration was 0.94.
TL;DR: Clinical manifestations associated with mold exposure in moisture-problem buildings will be described and numbers of exposed persons develop a hypersensitivity reaction to fungal allergens.
Abstract: The number of moisture-problem buildings in Finland is unexpectedly high according to recent investigations. In approximately 55% of Finnish buildings, moisture damage is in need of repair. With more than 1.15 million buildings in this country, almost 600 000 buildings suffer moisture problems and in over 100 000 there is growth of molds, either in building materials or on infested surfaces of the building. This means that over 400 000 Finns have been exposed to molds in damp houses. Exposure to molds is a significant health risk and should be prevented. Irritation of eyes, respiratory tract and skin may occur following exposure to microbes, and numbers of exposed persons develop a hypersensitivity reaction to fungal allergens. Asthma, hypersensitivity pneumonitis (extrinsic allergic alveolitis) and organic dust toxic syndrome (ODTS) may also develop after exposure. Secondary infections are more common in persons living in damp houses. In the present article, clinical manifestations associated with mold exposure in moisture-problem buildings will be described.
TL;DR: Indoor air guideline values are proposed for formic, acetic, propionic and butyric acid and the lowest of the proposed sensory irritation and health effect values was higher than, but otherwise in reasonable agreement with, established occupational exposure limits (OEL) multiplied by 1/40.
Abstract: Evaluation of sensory and health effects from indoor air exposures is hampered by the limited number of specific indoor air standards and guidelines. It is proposed that the evaluations be based on three values for each compound, an odour threshold, a value set for prevention of irritation of eyes and nose (sensory irritation) while all other non-genotoxic effects (including lung effects) are included in the category “health effects” and evaluated by means of a single value. Finally, it is also evaluated whether the substance is a genotoxic carcinogen. Indoor air guideline values are proposed for formic, acetic, propionic and butyric acid, based on published literature. For each substance the lowest of the proposed sensory irritation and health effect values was higher than, but otherwise in reasonable agreement with, established occupational exposure limits (OEL) multiplied by 1/40. This suggests that the OELs may play an important role in evaluations of the types of indoor air exposure effect mentioned.
TL;DR: Gender, family history of allergic diseases, dampness of the home and, to a lesser extent, passive smoking were important risk factors for life-time prevalence of respiratory symptoms in schoolchildren.
Abstract: The prevalence of respiratory symptoms and risk factors were gathered in four study centres in Western and Central Europe as part of an EU-funded multi-centre study addressing the use of small area methods in air pollution epidemiology (SAVI-AH). The study was carried out in Prague (CZ), Poznan (PL), Huddersfield (UK) and Amsterdam (NL). Prevalences of respiratory symptoms and risk factors between the centres were compared, and associations between risk factors and respiratory symptoms were calculated. Respiratory health was assessed by a self-administered questionnaire, distributed among parents or guardians of schoolchildren between the age of 7 and 11 years. Life-time wheezing and attacks of shortness of breath showed highest prevalences in Huddersfield (30% and 14%, respectively); usual cough showed highest prevalence in Poznan (27%). Differences in prevalence between the centres were found for the potential determinants “age” (due to different age ranges), “gas cooking” (highest in Amsterdam and Poznan), gas/coal heating (lowest in Central European centres), home dampness (highest in Western European centres), disturbance by traffic (highest in urban centres), maternal smoking (highest in Central European centres), family history (highest in Huddersfield) and education (highest in Huddersfield). The prevalence of pets in the home differed only slightly between the study centres. Of the potential deteminants studied, gender, family history of allergic diseases, dampness of the home and, to a lesser extent, passive smoking were important risk factors for life-time prevalence of respiratory symptoms in schoolchildren.
TL;DR: It is suggested that the performance of filtration/ventilation systems is the most critical parameter in reducing general particulate concentration levels in those hospital units where medical procedures can result in generation of potentially hazardous organic aerosols.
Abstract: Investigations of particle concentration levels and size distribution were conducted in the complex hospital system of the Royal Children's and the Royal Brisbane Hospitals in Queensland, Australia. The aim of the measurements was to provide an indication of particulate sources in the hospital environment and relate particle characteristics to the operating parameters of the hospitals. The measurements were performed using the most advanced instrumentation for size classification in the submicrometer and supermicrometer levels. The conclusions from the investigation were: (i) that indoor concentration levels of particle numbers are closely related to outdoor concentration levels, indicating that outdoor particulates were the main contributor to the indoor particulates in the hospitals under investigations; and (ii) that the performance of filtration/ventilation systems is the most critical parameter in reducing general particulate concentration levels in those hospital units where medical procedures can result in generation of potentially hazardous organic aerosols.
TL;DR: In this paper, the authors used a Computational Fluid Dynamics (CFD) model to simulate the three-dimensional air velocity profiles and Volatile organic compound (VOC) concentration distributions from wood stain in a well-designed mixing chamber of 1.0X0.8×0.5 m3.
Abstract: Most of the existing emission models developed from small-scale chamber tests assume complete mixing in the chamber throughout the test period. This paper examined this assumption using a Computational Fluid Dynamics (CFD) model. The model simulated the three-dimensional air velocity profiles and Volatile Organic Compound (VOC) concentration distributions from wood stain in a well-designed mixing chamber of 1.0X0.8X0.5 m3. The model used measured data to determine the time-dependent VOC surface concentrations of wood stain. The CFD results show that the VOC concentrations in the test chamber were not uniform in the early stage (about 18 minutes). The first-order decay model using the complete mixing assumption will underestimate the Total VOC (TVOC) emission rates by 65% and 59% in the first 3 minutes and next 15 minutes, respectively. Since wood stain emitted about one third of the VOCs in the first 18 minutes, the impact of incomplete mixing in the early period is significant for calculating the material emissions. Furthermore, the mass transfer coefficient of TVOC calculated by CFD is also compared with that calculated by analogue theory and that calculated by experimental correlation.