ALBERT

Notes: Abstract In laboratory experiments, we investigated two task/ambient conditioning systems with air supplied from desk-mounted air outlets to efficiently ventilate the breathing zone of heated manikins seated at desks. In most experiments, the task conditioning systems provided outside air while a conventional ventilation system provided additional space cooling but no outside air. Air change effectiveness (i.e., exhaust air age divided by age of air at the manikin's face) was measured with a tracer gas step-up procedure. Other tracer gases simulated the release of pollutants from nearby occupants and from the floor covering, and the associated pollutant removal efficiencies (i.e., exhaust air concentrations divided by concentrations at manikin's face) were calculated. High values of air change effectiveness (∼1.3 to 1.9) and high values of pollutant removal efficiency (∼1.2 to 1.6) were measured when these task conditioning systems supplied 100% outdoor air at a flow rate of 7 to 9 L s-1 per occupant. Air change effectiveness was reasonably well correlated with the pollutant removal efficiency. Overall, the experimental data suggest that these task/ambient conditioning systems can be used to improve ventilation and air quality or to save energy while maintaining a typical level of IAQ at the breathing zone.

Notes: Abstract Sixteen flights had been investigated for indoor air quality (IAQ) on Cathay Pacific aircraft from June 1996 to August 1997. In general, the air quality on Cathay Pacific aircraft was within relevant air quality standards because the average age of aircraft was less than 2 years. Carbon dioxide (CO2) levels on all flights measured were below the Federal Aviation Administration (FAA) standard (30,000 ppm). The CO2 level was substantially higher during boarding and de-boarding than cruise due to low fresh air supply. Humidity on the aircraft was low, especially for long-haul flights. Minimum humidity during cruise was below the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) minimum humidity standard (20%). The average temperature was within a comfortable temperature range of 23±2°C. The vertical temperature profile on aircraft was uniform and below the International Standard Organization (ISO) standard. Carbon monoxide levels were below the FAA standard (50 ppm). Trace amount of ozone detected ranged from undetectable to 90 ppb, which was below the FAA standard. Particulate level was low for most non-smoking flights, but peaks were observed during boarding and de-boarding. The average particulate level in smoking flights (138 (ig/m3) was higher than non-smoking flights (7.6 μg/m3). The impact on IAQ by switching from low-mode to high-mode ventilation showed a reduction in CO2 levels, temperature, and relative humidity.

Notes: Abstract The chemical and sensory emissions from five building materials (carpet, polyvinyl chloride (PVC) flooring, sealant, floor varnish and wall paint) were tested under different combinations of temperature and relative humidity in the ranges 18–28°C and 30–70% relative humidity (RH). The experiment was performed in a climate chamber where a specially designed test system was built to study emissions from the five materials. The test system could provide different temperatures and humidities of air around the materials, while the air, after being polluted by the emissions from the materials, could be reconditioned to 23°C and 50% RH for sensory assessments. The experiment was designed to separate the direct impact of temperature and humidity on perception from the impact on sensory emission. The study found little influence of temperature on the emissions from the five materials whether expressed in chemical or sensory terms. The effect of humidity was found to be significant only for the waterborne materials – floor varnish and wall paint. Compared with the direct impact of temperature and humidity on the perception of air quality, the impact of temperature and humidity on sensory emissions from the building materials has a secondary influence on perceived air quality.

Notes: Abstract Volatile organic emissions from particleboard, medium density fibreboard (MDF) and office furniture have been measured in dynamic environmental chambers, both small and room-sized. Characterisation of product emission properties in small chambers was possible when inter- and intra-sheet variations were considered. Formaldehyde emission factors for all products were approximately double European low-emission specifications and did not decay to the latter for several months. Long-term emission behaviour could not be predicted from short-term measurements. Volatile organic compounds (VOC) emissions were low for the MDF product, higher for particleboard, and highest for laminated office furniture. The compounds emitted differed from those reported in other countries. VOC emissions from the sheet products decreased more quickly than formaldehyde, reaching low levels within two weeks, except for MDF which was found to become a low-level source of hexanal after several months.

Notes: Abstract Birch and grass pollen grains as well as pollen-derived small particles appear as potent allergens in the outdoor air during spring and summer. The occurrence of pollen allergens in indoor air, however, has not been studied in depth due to lack of suitable sampling and analytical methods. Herein, a recently reported “direct on sampling filter estimation” (DOSAFE) technique (Acevedo et al., 1998) has been validated for quantification of pollen allergens in indoor air using two school rooms and two office rooms as experimental models. Using DOSAFE and polyclonal antibodies against water extracts of pollen from Betula pendula and Phleum pratense L, we found that indoor air of school and office rooms carried substantial amounts of pollen allergens, expressed as SQ units, predominantly occurring as particles with smaller diameters than the pollen grains. In one school room the indoor air birch pollen allergen concentrations increased from 242 to 403 SQ units/m3 over the sampling period although the corresponding outdoor air concentrations decreased from 350 to 90 SQ units/m3. Electrostatic air cleaning in one office room reduced its grass pollen allergen concentrations by more than 95% to 0.02–0.34 SQ units/m3 as compared to the control room.

Notes: Abstract Polyurethane products were subjected to chamber testing to determine their emission rates of 2,4- and 2,6-toluene diisocyanate (TDI). The polyurethane (PU) products included carpet padding, furniture cushions, sheet foam, varnishes, and sealants, as well as a commercially-applied water sealant product for concrete that contained up to 4 percent TDI by weight. The PU products were screened in a 9-L glass chamber, under elevated temperature and chamber loading conditions, using both a time-integrated sampling and analysis method specific for TDI and a continuous but non-specific real-time monitor for isocyanates. None of the products normally found in residences showed a positive response in the screening tests, indicating that TDI emissions and consequently toxic effects from such products are negligible. However, the commercially-applied water sealant gave a positive response in the screening test. Further testing of that product at realistic temperatures showed initial TDI emission rates of about 300,000 μg/m2/hr, with emissions lasting only one hour or less. At 21 and 27°C, about 1 percent and 5 percent, respectively, of the TDI content of the product was released to the air. The emitted TDI was predominantly the 2,6-isomer, although the TDI originally present in the product was predominantly the 2,4-isomer.

Notes: Abstract A simple test chamber method to quantify adsorption and desorption of organic compounds on material surfaces is described. Important environmental parameters such as temperature, relative humidity and air velocity were varied and controlled independently around typical indoor values. Experiments were performed with α-pinene and toluene in concentrations of 160-300 μg/m3. The measurements show adsorption on and desorption from wool carpet, nylon carpet, polyvinyl chloride (PVC) floor coverings, cotton curtain material and the empty chamber. The ranking of the materials, with respect to their sorption capacity, is as mentioned above. The adsorption of α-pinene was higher than the adsorption of toluene for all the materials. Air velocity was not found to influence the sorption of α-pinene and toluene on wool carpet, tested with air velocities at 0, 10 and 20 cm/s. The experiments were carried out during both the adsorption and the desorption phase. The uncertainty of the experiments was lowest during the desorption phase. Based on the results obtained, it can be recommended that sorption experiments should be performed as desorption phase experiments. A one-sink model, based on the Langmuir adsorption isotherm, appears adequate to describe the results.

Notes: Abstract Walk through questionnaires may be feasible tools to obtain data on the indoor environment in community studies. However, limited information is available regarding the reproducibility of the data obtained through these questionnaires. In this pilot study, two construction engineering students inspected ten dwellings twice by means of a standardized walk through questionnaire. The two engineering students inspected the dwellings independent of each other within two months. Time between the two visits varied between 14 and 40 days. The variables presented were based on information from the residents and inspection. The continuous variables recorded included number of rooms in the dwellings, room volume, length of filled shelves and textile area. The inter- and intra-observed variabilities were poorer for number of rooms and shelf factor than for the other variables. For the 3 of the 9 categorical variables based on inspection, the inter-observer comparison showed complete agreement with a kappa statistics of 1.0, these variables being condition of the window frames and construction of outside walls and roof. One of the categorical variables showed a kappa statistics of 〈0.5, these variables being presence of basement and presence of condensation at windows. This study indicates a wide variation in observer variability between various items of a walk through questionnaire. Clear definitions of all the parts of the questionnaire are needed, as well as thorough training of observers.

Notes: Abstract Data of chemical emissions from flooring materials have been collected and investigated in a database known as METS. The emission tests are performed using the Field and Laboratory Emission Cell (FLEC). The emission rates of total volatile organic compounds (TVOC) in the boiling point range of hexane to octa-decane varies from around 4,000 μg/(m2· h) to less than 10 μg/ (m2· h). Results obtained 1994/95 are presented and compared with the results obtained in 1992 for similar materials. The tests are performed 4 weeks and 26 weeks after the manufacturing of the material. The emission rates of TVOC decrease on the average approximately 60% from 4 to 26 weeks. The differences and trends in emission rates of individual chemicals and their use are discussed. For many VOCs emission rates decrease rapidly and become near to or below 2 μg/(m2· h) (the detection limit) after 26 weeks. For a small number of individual compounds the emission rate decrease little over 26 weeks. A small number of chemicals are singled out for particular interest in a health and comfort evaluation based on the emission results.

Notes: Abstract Various studies on indoor and outdoor particulate matter in the urban environment in the vicinity of busy arterial roads in the centre of the subtropical city of Brisbane have indicated that the revised United States Environmental Protection Agency National Ambient Air Quality Standards (US EPA NAAQS) for Particulate matter PM2.5 could be exceeded not only outdoors but also indoors. The aim of this work was to investigate outdoor exposure to submicrometer particles and their relationship with indoor exposure in a hypothetical office building located in the vicinity of a busy arterial road. The outdoor exposure values and trends were measured in terms of particle number in the submicrometer size range and were then recalculated to represent mass concentration trends. The results of this study indicate that exposure to PM0.7 particles in ambient air close to a busy road often exceeds the levels of the annual and 24-hour US EPA NAAQS PM2.5 standards. It is likely that exposure to PM2.5 is even higher, and may significantly exceed these standards.

Notes: Abstract Eighteen laboratories from 10 European countries participated in a comparison organized as part of the VOCEM project, a 2.5-year research collaboration among 4 research institutes and 4 industrial companies. The scope of the project was to improve the procedure used to measure volatile organic compounds (VOC) emitted from building materials and products in small test chambers. The interlaboratory comparison included the GC-MS determination of 5 target compounds from carpet, 8 from polyvinyl chloride (PVC) cushion vinyl and 2 from paint; for the first time, chamber recovery (sinks), homogeneity of solid materials and possible contamination during transport were tested. The results show that the intralaboratory variance (random errors) is much smaller than the interlaboratory variance (systematic errors). Causes of the largest interlaboratory discrepancies were: (i) analytical errors; (ii) losses of the heaviest compounds due to sorption on the chamber walls; and (iii) non homogeneity of the materials. The output of this work concerns both the objective of labelling materials with regard to their VOC emissions and the pre-standard drafted by the European Commitee for Standardization (CEN) for this type of determination.

Notes: Abstract To ensure prompt response by real-time air monitors to an accidental release of toxic aerosols in a workplace, safety professionals should understand airflow patterns. This understanding can be achieved with validated computational fluid dynamics (CFD) computer simulations, or with experimental techniques, such as measurements with smoke, neutrally buoyant markers, trace gases, or trace aerosol particles. As a supplementary technique to quantify airflows, the use of a state-of-the art, three-dimensional sonic anemometer was explored. This instrument allows for the precise measurements of the air-velocity vector components in the range of a few centimeters per second, which is common in many indoor work environments. Measurements of air velocities and directions at selected locations were made for the purpose of providing data for characterizing fundamental aspects of indoor air movement in two ventilated rooms and for comparison to CFD model predictions. One room was a mockup of a plutonium workroom, and the other was an actual functioning plutonium workroom. In the mockup room, air-velocity vector components were measured at 19 locations at three heights (60, 120 and 180 cm) with average velocities varying from 1.4 cm s−1 to 9.7 cm s−1. There were complex flow patterns observed with turbulence intensities from 39% up to 108%. In the plutonium workroom, measurements were made at the breathing-zone height, recording average velocities ranging from 9.9 cm s−1 to 35.5 cm s−1 with turbulence intensities from 33% to 108%.

Notes: Abstract The age of the air in a room is normally determined either from a pulse response or from a step change response (up or down). There are a certain number of problems involved in applying these two theoretical models, especially those associated with the duration of the injection, which must either be infinitely short or infinitely long. A hybrid method that consists of injecting a known quantity of tracer for a given time offers the advantages of both methods. The equation for calculating age is exact, regardless of the type of flow considered, and is derived from the expressions already established for a pulse response to which a correction is included to account for the tracer generation function. If a rectangular pulse is used for the injection, the solution is particularly simple.

Notes: Abstract The aim of the study was to describe how allergies and non-allergies perceive the same environment. All high school students in a town in southern Sweden were invited to answer a questionnaire concerning allergy, subjective symptoms, annoyance reactions and perception of the environment (response rate: 81%). The results show that only 45% of the students were non-allergic (n = 1,715). Since the symptom frequency among non-allergic students was normal, the schools were classified as healthy. However, compared to the non-allergic students, a higher percentage among the allergies suffered from symptoms every week, a lower percentage was satisfied with the air quality and the cleaning, and a higher percentage was bothered every week by temperature, stuffy/stale air, bad odor, passive smoke, bad lighting, noise, dust and dirt (ANOVA, P 〈 0.05). The findings could indicate that allergies note discomfort earlier than non-allergies by being more critical in general and especially critical to factors that could effect their health. The findings could also indicate that awareness of ones own sensitivity could lead to attention to different risk factors, which in turn could lead to stress/anxiety, which could make symptoms worse. The conclusion is that it is important to take allergy into consideration when the environment is assessed.

Notes: Abstract Five classrooms, air-conditioned or naturally ventilated, at five different schools were chosen for comparison of indoor and outdoor air quality. Temperature, relative humidity (RH), carbon dioxide (CO2), sulphur dioxide (SO2), nitric oxide (NO), nitrogen dioxide (NO2), particulate matter with diameter less than 10 mm (PM10), formaldehyde (HCHO), and total bacteria counts were monitored at indoor and outdoor locations simultaneously. Respirable particulate matter was found to be the worst among parameters measured in this study. The indoor and outdoor average PM10 concentrations exceeded the Hong Kong standards, and the maximum indoor PM10 level was even at 472 μ;g/m3. Air cleaners could be used in classrooms to reduce the high PM10 concentration. Indoor CO2 concentrations often exceeded 1,000 μl/l indicating inadequate ventilation. Lowering the occupancy and increasing breaks between classes could alleviate the high CO2 concentrations. Though the maximum indoor CO2 level reached 5,900 μl/l during class at one of the sites, CO2 concentrations were still at levels that pose no health threats.

Notes: Abstract The influence of a thermal heterogeneity boundary conditions on the air change efficiency (ACE) of a mechanical ventilation system in a test room was experimentally evaluated by means of the “step-down” tracer gas technique in 24 different experimental conditions. The experiments were performed under isothermal condition, varying the air supply temperature with respect to the walls and varying the surface temperature of a wall with respect to the other walls and the supply air, simulating both heating and cooling situations. Changing the position of the outlet grid two different configurations of the ventilation system were tested. The nominal supply air velocity varied between 0.04 and 0.11 m/s, corresponding to a range from 1 to 3 ach, and the temperature differences varied from 0 to 5°C. Results are reported in terms of air change efficiency indexes, both local and global. The global air change efficiency (ACE), values are presented as a function of the Archimedes number (Ar), whose values were in the range 0 to 181. The reported results suggest that the Ar number may be used to organize the ACE values when in the presence of thermal heterogeneity, both in the external envelope and in the supplied air. The obtained results show that there is a logarithmic relation between Ar and ACE. In particular, for both ventilation strategies tested, the increase of the absolute value of Ar leads to an increase of ACE when the supply air is warmer than the walls, and to a decrease of ACE when the supply air is colder than the walls. Under isothermal conditions the Reynolds number (Re) fairly correlates the experimental results.

Notes: Abstract Emission models developed using small chamber data were combined with an Indoor Air Quality (IAQ) model to analyze the impact of volatile organic compound (VOC) emissions from latex paint on indoor environments. Test house experiments were conducted to verify the IAQ model's predictions. The agreement between model predictions and experimental measurements met the American Society for Testing and Materials criteria for model verification in the room with the source and met most of the requirements in other rooms. The major cause of disagreement between the model predictions and the experimental data in the test house appears to be an inadequate sink model.

Notes: Abstract Aerosol particles in municipal atmospheres are of increasing public health concern; however, since most of our time is spent indoors, indoor aerosols must be researched in counterpart. Compact High-Efficiency Particulate Air (HEPA) filter systems are commonly employed in residences to alleviate airborne dust concentrations. In this study, a detailed and original methodology was used to determine concentrations and types of submicrometer aerosols, as well as of large (〉4 μm) dust particles. Scanning electron microscopy was used to quantify and characterize ambient aerosols collected from filtered and non-filtered rooms. Particle concentrations were significantly lower in samples collected in the presence of the filter system (mean 23 to 8 coarse particles liter−1, 63% reduction; 13 to 3 inorganic submicron particles cm−3, 76% reduction; 85 to 33 total submicron particles cm−3, 62% reduction; all P 〈 0.05). This study provides a new methodology for analysis of indoor aerosols and new data on their physico-chemical characteristics. Since the filter systems are effective at reducing submicron aerosol concentrations, they may improve the health of individuals such as asthmatics, who experience health problems caused by anthropogenic fine particles.

Notes: Abstract This paper reports the development of methods for calculating a ventilation performance metric that is a measure of the airflow pattern in a room or zone of a multi-zone ventilation system. Temporal mixing theory is used as the basis for these methods. The methods are applicable to all ventilated systems that can be modeled as a set of interconnected chambers. Relations between the ventilation performance metric defined in this paper and those defined previously are derived. The theoretical results of this paper are consistent with published experimental findings. They also illustrate that the conclusions in some experimental studies about the airflow patterns in working buildings may be incorrect. Re-analysis of previously published data illustrates how common features of mechanically ventilated buildings, such as recirculation of return air and multiple chambers, confound information about airflow patterns in tracer gas data. The calculation methods developed in this paper can be used to undo this confounding.

Notes: Abstract The exposure-response relationship between the concentration of air pollutants and perceived air quality was studied for eight materials often found indoors and for a mixture of three of the materials. Samples of the materials were placed in a ventilated test chamber. The exhaust air from the test chamber was diluted with different rates of unpolluted air to obtain five different concentrations of polluted air. A sensory panel assessed the perceived quality of the five concentrations of polluted air. The exposure-response relationship differed between the materials and also from the corresponding relationship for human bioeffluents. The exposure-response relationships can be described by straight lines in a log-probit plot and be defined by two constants characteristic for each material. Determination of the two constants characterizing each material requires sensory assessments at least at two pollution concentrations. The sensory pollution load for a material may change with the pollution concentration in the air. The use of a simple measurement method based on a dilution system connected to a ventilated small-scale test chamber is proposed to characterize the emissions from materials in sensory and chemical terms.

Notes: 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.

Notes: Abstract Complaints about unpleasant odour from wall, ceiling and floor coverings made of composite cork, induced chamber tests to study the emissions of volatile organic compounds (VOC) from composite cork products for indoor use. Emissions of phenol and furfural were found to be high, particularly those from cork parquet. Emission factors after 1 week ranged from 150 to 650 μg m−2 h−1 and from 15 to 350 μg m−2 h−1 for phenol and furfural, respectively, and decreased only slowly over time, by a factor of approx. 10 for a 6-month period. The ranges of emission factors were found to be similar for some solvents such as cyclohexanone or toluene which are constituents of varnishes used to protect cork surfaces. The emission of furfural may result from chemical reactions in the cork during the production process or may be caused by additives such as binders.

Notes: 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.

Notes: Abstract Experiments were conducted to evaluate the survival time of randomly selected female D. farinae exposed to temperatures from 40 to 80°C and relative humidities (RHs) between 10 and 90%. Significant temperature effects were found on the length of time mites can survive under those conditions. The time needed to induce 100% mortality for female D. farinae held at 40°C varied between 39 and 84 h. At 70 and 80°C, all mites died within 5 minutes. At 50°C and above, RH had little influence and temperature alone was the determining factor for mite survival. The length of survival time decreased precipitously between 40 and 50°C, suggesting that a loss of physiological integrity of female D. farinae probably occurred in this range. The results of this study indicated that the technique of raising temperatures to above 40°C for a short duration can be used to reduce living house dust mite populations in homes significantly.

Notes: Abstract The effects of two substrates - a stainless steel plate and a gypsum board - on the volatile organic compound (VOC) emissions from a latex paint were evaluated by environmental chamber tests. It was found that the amount of VOCs emitted from the painted stainless steel was 2 to 10 times more than that from the painted gypsum board during the 2-week test period. The dominant chemical species emitted were also different between the two substrates. Data analysis indicated that most VOC emissions from the painted stainless steel occurred in the first 100 h via a fast, evaporation-like process. On the other hand, the majority of the gypsum board VOCs were emitted in a later stage via a slow, diffusion-controlled process. There were measurable emissions of VOCs 11 months after paint application on the gypsum board. It is suggested that, instead of the routinely used substrates such as stainless steel plates, real substrates such as wood or gypsum board should be used for the evaluation of emissions in indoor environments.

Notes: Abstract The existing literature contains strong evidence that characteristics of buildings and indoor environments significantly influence rates of respiratory disease, allergy and asthma symptoms, sick building symptoms, and worker performance. Theoretical considerations, and limited empirical data, suggest that existing technologies and procedures can improve indoor environments in a manner that significantly increases health and productivity. At present, we can develop only crude estimates of the magnitude of productivity gains that may be obtained by providing better indoor environments; however, the projected gains are very large. For the U.S., we estimate potential annual savings and productivity gains of $6 billion to $19 billion from reduced respiratory disease; $1 billion to $4 billion from reduced allergies and asthma, $10 billion to $20 billion from reduced sick building syndrome symptoms, and $12 billion to $125 billion from direct improvements in worker performance that are unrelated to health. Sample calculations indicate that the potential financial benefits of improving indoor environments exceed costs by a factor of 18 to 47. The policy implications of the findings are discussed and include a recommendation for additional research.

Notes: Personal exposure in a displacement ventilated room is examined. The stratified flow and the considerable concentration gradients necessitate an improvement of the widely used fully mixing compartmental approach. The exposure of a seated and a standing person in proportion to the stratification height is examined by means of full-scale measurements. A breathing thermal manikin is used to simulate a person. It is found that the flow in the boundary layer around a person is able to a great extent to entrain and transport air from below the breathing zone. In the case of non-passive, heated contaminant sources, this entrainment improves the indoor air quality. Measurements of exposure due to a passive contaminant source show a significant dependence on the flow field as well as on the contaminant source location. Poor system performance is found in the case of a passive contaminant released in the lower part of the room close to the occupant. A personal exposure model for displacement ventilated rooms is proposed. The model takes the influence of gradients and the human thermal boundary layer into account. Two new quantities describing the interaction between a person and the ventilation are defined.

Notes: Abstract Mechanical ventilation of workrooms was formerly based mainly on the dilution principle. In recent years, however, 50% of new investments in industrial ventilation in Scandinavia have been spent on displacement ventilation. Very little data exist from industrial settings on the relative performance of displacement ventilation versus dilution ventilation as regards air quality and thermal comfort. The present study collected data on the indoor climate in a sewing plant before and after the ventilation was changed from dilution to displacement. The indoor climate was evaluated by hygienic measurements of air pollution, temperature, air velocity, etc., and 40 employees were interviewed about perceived thermal comfort, air quality, and irritative symptoms.Changing the ventilation from dilution to displacement induced a slightly higher air change in the occupied zone of the plant and entailed higher temperature gradients. In spite of these findings, complaints of draught decreased significantly, and temperature was perceived to be more pleasant after the change. The air was perceived as less heavy and less dry, especially when humidification was added to the supply air. The improvements in the workers’ reports on the environment could not be attributed to placebo effects. Generally, the hygienic measurements were improved or unchanged after the change in ventilation system. Thus, displacement ventilation improved environmental conditions in this study. When adding humidification, this improvement was further sustained.

Notes: Abstract The air change effectiveness (ACE), an indicator of the indoor airflow pattern, was measured in twenty-six laboratory experiments. Ventilation air was supplied through induction-type diffusers located in the ceiling and removed through a ceiling mounted return grille. The tracer-gas step-up measurement procedure was employed. In five of the experiments, pollutant removal efficiencies were also measured for simulated pollutant emissions from the floor covering and for simulated emissions from occupants. In experiments with heated supply air, supply airflow rates typical of the minimum supply flow rates of VAV ventilation systems, and 100% outside air, the ACE ranged from 0.69 to 0.89. These results indicate that significant short-circuiting of ventilation air between the supply air diffuser and return air grille does occur under these adverse conditions. Mechanical recirculation of air, so that the supply air contained approximately 50% outside air, increased the ACE by about 0.05. When the supply air was cooled, the ACE ranged from 0.99 to 1.15, adding to existing evidence that short-circuiting is rarely a problem when the building is being cooled. The pollutant removal efficiency for simulated pollutant emissions from the floor covering (PREfloor) was strongly correlated with ACE (R2= 0.98) and the values of PREfloor were within approximately 0.1 of the values of ACE. The pollutant removal efficiency for simulated pollutant emissions by occupants varied between workstations and was not as well correlated with the ACE.

Notes: Abstract A simple method for quantifying dust on indoor non-textile surfaces has been developed and evaluated. The method uses gelatine foils to sample particles from surfaces, applying a constant pressure. The foils possess unique properties, making them particularly suitable for evaluation by light extinction. The amount of particles collected as measured by laser light extinction is expressed as the area percentage covered by particles. Foil sampling effectiveness has been estimated to range from 87% to 97%. A simple method for calibrating the instrument has been developed. The relation between the total projected particle area excluding overlap can be determined from the measured projected area including overlap from a simple equation. An overall uncertainty is given, including effects of positioning foils in the detector, sampling from rough surfaces, and the natural variability due to the discrete nature of particles. The lower level of detection for dust on an object is less than 0.5% surface area covered by dust. The method has formed the basis for suggesting a sampling strategy and surface dust limits in relation to cleaning and the quality of the indoor environment.

Notes: Abstract Adjustment of ventilation rates in buildings is widely practised, both to provide good air quality on a proactive basis and to mitigate air quality problems associated with occupant complaints. However, both cross-sectional and experimental epidemiological studies have reported mixed results and have for the most part failed to establish definitive relationships between ventilation rates and symptom prevalence or dissatisfaction with air quality. The difficulties involved in establishing such relationships may be due to a variety of confounding factors which include limitations in study design and interaction effects; difficulties in controlling ventilation rates in experimental studies; inadequate mixing of supply air in occupied spaces; high source strengths for some contaminants; dynamic interactions between sources and ventilation rates that result in increased contaminant emissions; contaminant dose-response sensory effects which are log-linear; potential contaminant generation within ventilation systems themselves; and multifactorial genesis of sick building symptoms.There is limited evidence to suggest that ventilation rate increases up to 10 L/s person may be effective in reducing symptom prevalence and occupant dissatisfaction with air quality and that higher ventilation rates are not effective. Because of complex relationships between ventilation rates, contaminant levels, and building-related health complaints/dissatisfaction with air quality, the use of ventilation as a mitigation measure for air quality problems should be tempered with an understanding of factors which may limit its effectiveness.

Notes: Abstract Humidifiers, used in approximately 25% of Canadian homes, may potentially aggravate asthma by increasing the airborne concentrations of fine particles and microbials. A randomized controlled study was carried out to investigate the acute effects of humidifier use on asthma control. Daily peak flows, asthma symptoms and need for medication were assessed during 2 weeks (period 1) when 110 subjects were using humidifiers and during the following 3 weeks (period 2) when half of the subjects were randomized to stopping the humidifier and the other half to continuing its use. In the intervention group, mean morning peak flows were 357 L/min (SEM 17) during humidifier use (period 1) and 352 L/min (SEM 16) when humidifiers were not used, a difference of - 4.4 L/min (95%CI - 11.2 to 2.3) (period 2). Respective values in the control group were 403 L/min (SEM 16) during period 1 and 405 L/min (SEM 16) during period 2. No significant differences were found when analyses were restricted to portable humidifiers, allergies to mites and/or molds, and infrequently cleaned humidifiers. Humidifiers cause no short-term adverse health effects in the majority of those with asthma. Future studies should address the broader question concerning the chronic effects of increased home humidity on microflora and health.

Notes: Abstract A study was undertaken to investigate the use of mass balance modeling techniques to predict air pollution concentrations in residential settings where the source is evaporative emissions of alternative fuels emitted in the attached garage. Field study measurements of the spatial and temporal distribution of evaporative emissions in an attached garage were used to conduct this investigation. In this field study, known quantities of methanol were allowed to evaporate in the garage. Methanol concentrations were then measured and simulated in the garage. Because chemical and physical properties of this contaminant are clearly understood, it was possible to simulate the concentrations inside the remainder of the house.A multi-zonal mass balance model (CONTAM88) was used to predict the across-residence spatial and temporal distribution of concentrations of evaporative emissions from a methanol source inside the attached garage. The model's input data include physical characteristics of the house; parameters characterizing the leakiness of the house; heat, ventilation and air-conditioning system characteristics; fixed airflow data from vent registers; on-site meteorological measurements; and information on the contaminant source.Before using the model to simulate methanol dispersions, the model's performance was tested. Sulfur hexafluoride (SF6) measurements were taken throughout the residence and garage. The model was used to predict interzonal airflow rates and SF6 concentration distributions within the garage and the house, as well as to investigate the well-mixed zone assumption for the garage. Modeling results show that predicted garage SF6 concentrations agreed reasonably well with the measured concentrations under mixed conditions, but the model underpredicted the SF6 concentrations within rooms of the house where mixing was probably incomplete. Methanol simulation results showed that the model underpredicted by approximately 15 percent the garage methanol concentration after methanol emissions stopped.This study found that evaporative emissions in an attached garage have a tendency to infiltrate the house, with rooms adjacent to the garage showing the highest levels of methanol concentrations. Thus automotive evaporative emissions may represent a source of indoor pollution and human exposure in a residential attached garage and also in other critical locations of the residence.

Notes: Abstract The objective of this study was to assess the magnitude and balance of mechanical ventilation in the rooms of Helsinki metropolitan office buildings with different types of ventilation systems. A random sample of 50 office buildings was selected from the Building Registry. Of these buildings, the 33 that have a mechanical ventilation system were included in this study. Most office buildings in the Helsinki metropolitan area have a ducted supply and exhaust system and hot water radiator heating. Air recirculation is used in about half of the buildings which have a mechanical supply and exhaust system. The average exhaust airflow was 1.2 L/s, m2 (SD 0.73) or 17.2 L/s per person (SD 11.6). The variation of the airflows was found to be very high among the buildings, and among the rooms within the buildings. Therefore, even though the ventilation rates on average comply with the Finnish building code, it was found that many people were working in offices with airflows which were either too low or unnecessarily high.

Notes: Abstract Analysis of the impact of sources on indoor pollutant concentrations and occupant exposure to indoor pollutants requires knowledge of the emission rates from the sources. Emission rates are often determined by chamber testing and the data from the chamber test are fitted to an empirical model. While the empirical models are useful, they do not provide information necessary to scale the chamber data to buildings nor do they provide information necessary to understand the processes controlling emissions. A mass transfer model for gas-phase-limited mass transfer is developed and described in this paper. Examples of sources with gas-phase-limited emissions are moth cakes, floor wax, stain, and varnish. The mass transfer model expresses the emission rate in terms of a mass transfer coefficient and a driving force. The mass transfer coefficient can be predicted from correlations of the Nusselt number and the Reynolds number. The experiments and data analysis used to develop the correlation are described in the paper. Experiments to verify the assumptions used to describe the driving force are also described. Suggestions for using data from existing empirical emission models to determine parameters for the mass transfer model are provided. The mass transfer model provides a significantly better fit to data from an indoor air quality test house than does the empirical first order decay model.

Notes: There is a growing concern about indoor air quality (IAQ) in schools. We have studied relations between subjective indoor air quality (SIAQ) and measured IAQ among school personnel (N = 97) in six mid-Swedish primary schools. Information on SIAQ and the psychosocial work environment was measured by a self-administered questionnaire, using analogue rating scales. Indoor exposures were quantified by hygienic measurements. Perception of high room temperature was related to a poor climate of cooperation, fleecy wall materials, and the concentration of volatile organic compounds (VOC), including xylene, limonene, and butanols. Perception of air dry-ness was related to atopy, work stress, poor climate of cooperation, high room temperature, low air humidity, and high VOC concentration, including, limonene, and n-alkanes. Perception of dusty air was related to work stress, the role of schoolteacher, and exposure to 2-ethyl-1-hexanol. No relations were found between SIAQ and CO2, building age, or respirable dust. To achieve a good SIAQ, room temperature should be kept at a maximum of 22°C, and exposure to VOCs and fleecy materials should be minimized. Finally, a sound psychosocial work climate is essential for the perception of a good physical indoor climate.

Notes: Tracer gas studies were conducted around four model houses in a wind tunnel, and around one house in the field, to quantify re-entrainment and dispersion of exhaust gases released from residential indoor radon reduction systems. Re-entrainment tests in the field suggest that active soil depressurization systems exhausting at grade level can contribute indoor radon concentrations 3 to 9 times greater than systems exhausting at the eave. With a high exhaust concentration of 37,000 Bq/m3, the indoor contribution from eave exhaust re-entrainment may be only 20% to 70% of the national average ambient level in the U.S. (about 14 Bq/m3), while grade-level exhaust may contribute 1.8 times the ambient average. The grade-level contribution would drop to only 0.18 times ambient if the exhaust were 3,700 Bq/m3. Wind tunnel tests of exhaust dispersion outdoors suggest that grade-level exhaust can contribute mean concentrations beside houses averaging 7 times greater than exhaust at the eave, and 25 to 50 times greater than exhaust midway up the roof slope. With 37,000 Bq/m3 in the exhaust, the highest mean concentrations beside the house could be less than or equal to the ambient background level with eave and mid-roof exhausts, and 2 to 7 times greater than ambient with grade exhausts.

Notes: The objective of this study was to compare measured indoor air concentrations of toluene, from an adhesive used in installing floor tiles, with concentrations estimated from a multi-chamber indoor air quality model. Measurements of toluene emissions from floor adhesive with and without tiles covering the adhesive were made using a small chamber. Emission data from the chamber measurements were used as input to the indoor air quality model. The modeling results were compared with concentrations of toluene measured in a research house when adhesive was applied in a bedroom of the house. Three zones of the house were defined for modeling purposes-the bedroom in which the adhesive was applied, the remainder of the upstairs area, and the downstairs area. Zone-specific volumes and infiltration/exfiltration and interzonal airflows measured during and after adhesive application were also used as model inputs. Relatively good correspondence between measured and model concentrations was obtained, particularly in the bedroom where the adhesive was applied. Modeled concentrations were fairly sensitive to the input matrix of airflow rates.

Notes: 100 drivers aged 23-65, 53 male and 47 female, were recruited to drive an apparently unmodified passenger car for one hour in city traffic. They were randomly assigned either to a control condition, or to ionised air containing 20 000-30 000 negative ions/ml, but were unaware of the presence of an ioniser in the vehicle. A computer initiated unprepared signals to which drivers should normally be alert. Drivers responded by pressing a foot-switch and reporting verbally. Signals were selected at random from 21 possible signals, and were presented for up to 3 minutes, with a random delay of 30-180 seconds after each response or failure to respond. Subjects reported subjective symptom intensity by marking a set of 11 visual-analogue scales. Eye symptoms were alleviated by ionisation for subjects aged 〈 40 years (P〈0.05), but older female subjects experienced more eye discomfort, headache and fatigue in the ionisation condition (P 〈 0.05). Detection of 10 of the 21 signals was better (P 〈 0.05, 2-tail) in the ionisation condition. The effect was more often significant in the second half-hour, for subjects 〈 40 years, and for women. A significant negative effect (P 〈 0.05) was observed for the signal indicating speed below true speed.

Notes: The propensity of various types of home humidifiers to support and disseminate microbial contaminants into indoor air was tested. Reservoir water and air discharged from humidifiers seeded in the laboratory or naturally contaminated in the home were analyzed by standard microbiological methods. Clinically insignificant as well as overt or potentially pathogenic microorganisms were found to colonize the reservoirs of all types of humidifiers, but only cool mist and ultrasonic units readily aerosolized bacteria and endotoxin. Only cool mist units emitted hydrophobic fungal spores. Cool mist units discharged the greatest number of water particles in the inhalabk size range (4–16 μm) while ultrasonic units were more likely to emit respirable-sized water particles (〈 0.2–4 μm). Overt pathogens isolated from humidifiers in homes included Legionella and a pathogenic Acanthamoeba. Aerosolizing humidifiers should thus be avoided if frequent, thorough cleaning of the units is not practical.

Notes: The role of ventilation in the housing stock is to provide fresh air and to dilute internally generated pollutants in order to assure adequate indoor air quality. Blower doors are used to measure the air tightness and air leakage of building envelopes. As existing dwellings in the United States are ventilated primarily through leaks in the building shell (i.e., infiltration) rather than by whole-house mechanical ventilation systems, accurate understanding of the uses of blower-door data is critical Blower doors can be used to answer the following questions:〈list xml:id="l1" style="custom"〉•What is the Construction Quality of the Building Envelope?•Where are the Air Leakage Pathways?•How Tight is the Building?•How Much Ventilation Does the Air Leakage Supply?•How Much Energy Does the Air Leakage Lose?•Is this Building Too Tight?•Is this. Building Too Loose?•When Should Mechanical Ventilation be Considered?Various ASHRAE Standards (e.g., 62, 119, and 136) are used to determine acceptable ventilation levels and energy requirements.

Notes: The mixing rate of pollutants emitted from indoor sources influences the effectiveness of pollutant removal by building ventilation and the potential variability of exposure for a given release scenario. Quantitative information is scant on the mixing rate and the factors that govern it. We present mixing data for an instantaneously released tracer gas, carbon monoxide, in a sealed, unoccupied room under a range of forced airflow conditions, in which the flow is induced by blowers. The resulting mixing times, from 2 to 42 minutes, are related to the mechanical power of the air jets produced by the blowers. Mixing times are found to correlate well with the inverse of the cube root of power, in accordance with theoretical predictions and experimental observations for mixing in chemical reactors. The exposure index, defined as the time-averaged concentration at a point relative to the time-averaged concentration for the room as a whole, is presented for three experimental conditions, yielding quantitative information on the appropriateness of the well-mixed hypothesis under various flow conditions. In general, the exposure period following instantaneous release of a point-source pollutant must be much greater than the mixing time for the assumption of uniform mixing to hold. The correlation between mixing time and power input is used to predict the mixing time from the mixing action of a supply air jet for a typical ventilation scenario. The predicted mixing time, τmix∼7 min, is substantially lower than the time scale for removal by ventilation, τvent∼48 min. Under these conditions, complete mixing of an instantaneous release, point-source pollutant would be approximately attained within the interior space well before the pollutant would be thoroughly removed by ventilation.

Notes: The mean skin temperatures as well as the temperatures of the hands, feet and forehead of small children were measured in nurseries at air temperatures of 20°C and 22°C. Differences were studied between babies remaining still, babies crawling on tiling, wooden floors or rubber foam groundsheets, and older walking children. The results suggest that an air temperature of 22°C leads to skin temperatures comparable to those observed for resting adults in comfort, while 20°C seems to induce a slight but overall cooling of the body and considerable cooling of the extremities for the babies remaining still. The material of floor coverings should be considered carefully and preference given to low conductivity materials. Assuming that the optimum skin temperatures are the same for children and for adults, it appears that the PMV-PPD approach can be used to predict this particular optimum comfort condition, provided an increase of 20 wm−2 is taken into account for the metabolic rate of the small children.

Notes: Ventilation displacement systems have, during the last ten years, become more and more popular. In these systems cool air is supplied to the room, and the air is heated by heat sources. The rising air above these heat sources is of paramount importance to the behaviour of the ventilation displacement systems. In the present work the turbulent flow in plumes is studied numerically, using finite volume methods. The standard r-ɛ model was found to underpredict the spreading of the plumes, and it was thus modified in two ways so as to predict spreading rates in agreement with experiments. We present a comprehensive comparison between predictions and experiments including spreading rates, velocity and temperature profiles, and turbulent shear stresses. The volume flow rate versus the vertical distance from the plume is also presented. Good agreement between predictions and experiments is obtained.

Notes: The results of measurements of indoor air formaldehyde concentrations in occupational and private residences are presented for the period 1986 to 1993, based on requests of persons who complained about irritations. In many cases, climatic parameters such as the air exchange rate, temperature and relative humidity were also monitored. Calculated mean values for temperature and humidity were 22°C and 45% respectively. The average air exchange rate was 0.36 h−1, which is well below a recommended guideline value of 0.8 h˜' and it was evident that the ventilation is clearly insufficient in many rooms. The average formaldehyde concentration was 119 μg/m −3 (252 data), which is only slightly below the German guideline value of 125 μg/m −3. In 31% of the cases this guideline was exceeded. As expected, a clear relation between formaldehyde concentrations and the air exchange rate was found. The highest levels result at AE≤0.8 h−1, but only a single value exceeds 125 μg/m −3 at AE≥0.8 h−1. The association of law ventilation rates with high formaldehyde levels is also evident from a comparison with theoretical data after normalization to AE=0.8 h−1, using the Hoetjer-equation. It was also observed that the calculated annual mean concentrations decreased from 1986 to 1993.

Notes: The odor of 13 linoleum samples was investigated by different methods. 1) Gas chromatography (GC) with sniffing was used to ensure that no significant odorant was overlooked. 2) Odor intensity evaluation of the linoleum samples was correlated with GC data from Part 1 of this study. Partial least squares regression yielded two factors capable of explaining 77% of the odor intensity variation. The most important classes of compounds were 2-alkenals and fatty acids. 3) Odor indexes of the individual VOCs were compared in order to evaluate their relative odor impact. 4) The odor of linoleum was simulated by a synthetic mixture compounded according to the GC data. It had an odor closely resembling that from certain varieties of linoleum.

Notes: Abstract Processes involved in pollutant emissions from a dry-process photocopier have been investigated in a controlled room dynamic environmental chamber. Volatile organic compound (VOC) emissions occurred at a constant rate dependent on copy speed. However, VOC emission rates per copy were increased by increases in chamber temperature (e.g., a 20% increase resulted from increasing temperature from 23°C to 32°C) or changing from single- to double-sided operation (40% increase). Respirable particle emissions occurred under copier-idle mode (probably from residues in the machine) as well as with copying. No significant chamber sink effects were observed for VOCs or respirable particles. Small emissions of nitrogen dioxide, ozone and formaldehyde were observed but were difficult to interpret. A procedure for assessing pollutant emissions from photocopiers is recommended.

Notes: Abstract 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 in-terleukin–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-polysac-charide 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 bio-mass. The inflammatory properties of house dust upon inhalation may be reflected in its high potency to induce cytokine response in lung epithelial cells.

Notes: Abstract Validated instruments are not available to assess the residential characteristics. The aim of this study was to assess the reliability and validity of an interviewer-administered home visit report. The validity of 48 items in the Home Visit Report was examined against: observations made by a researcher, measurements of relative humidity, cat allergen, and ergosterol, a bio-marker of fungal exposure and a biochemical test. Test-retest reliability of 10 fixed residential characteristics was assessed comparing the responses obtained in the main study with the pilot study. Kappa, ANOVA and Wilcoxon Rank Sum tests were applied to assess the agreement and P〈0.05 was considered as statistically significant. Among 44 items examined for the validity against observations, there was a perfect or almost perfect agreement in 21 (K=0.9−l) and substantial agreement (K=0.6−0.8) in 19. Higher cat allergen levels were observed with cat ownership and cat being allowed indoors. Observed condensation was associated with relative humidity and observed mould was associated with ergosterol levels. The agreement on the type of carpet and the test was substantial (K=0.6). Among 10 items examined for reliability, there was a perfect or almost perfect agreement in 9 (K=0.9−l) and substantial agreement (K=0.7) in one. In conclusion, the Home Visit Report validated in this study provides reliable and valid data.

Notes: Abstract The mechanical exhaust system, where outdoor air is supplied through infiltration and devices in the building shell, is a common ventilation technique in multi-family buildings in Europe. The objective of this paper is to determine how well the system meets indoor air quality standards and regulations and how sensitive it is to disturbances, such as window opening, temperature differences and resident behavior, and how different building construction parameters affect the airflow. A simple model of a multi-family building has been simulated with a multi-zone infiltration program. It was found that the system almost never fulfills the regulations and that the actions of one resident can often affect the airflow in other apartments. The use of standards and regulations defining indoor air quality and energy efficiency will be ineffective for these systems because they are not stable, that is, sensitive to disturbances such as weather changes and resident behavior.

Notes: Abstract With the greater use of air-conditioned offices in Singapore, achieving good indoor air quality has become an important issue. The laws that impose duties upon designers and contractors with respect to the design and construction of air-conditioning and mechanical ventilation (ACMV) systems are set out in the Building Control Regulations and the Singapore Standard Code of Practice for Mechanical Ventilation and Air-conditioning in Buildings (hereinafter “SS CP 13:1980”). ACMV maintenance is governed by the Environmental Public Health Act, the Building and Common Property (Maintenance and Management) Act, and the Land Titles (Strata) Act, as well as by lease or tenancy agreements. Designers, contractors, developers, building owners and management corporations may also be liable to the workers, occupants and other premises users for indoor air quality (IAQ)-related injuries under the general principles of contract and tort. Recently, the Guidelines for Good Indoor Air Quality in Office Premises was issued by the Ministry of Environment to complement SS CP 13:1980 toward improving the indoor air quality of air-conditioned office premises. Although the Guidelines have no statutory effect, they may be adopted as contractual requirements in construction, lease and maintenance contracts. They may also be used to determine the relevant standard of duty of care required to discharge tortious liability. This paper looks at the existing laws and rules affecting the design, construction and maintenance of air-conditioned offices in light of Part III of the Ministry's Guidelines.

Notes: Abstract Perceived air quality, Sick Building Syndrome (SBS) symptoms and productivity were studied in an existing office in which the air pollution level could be modified by introducing or removing a pollution source. This reversible intervention allowed the space to be classified as either non-low-polluting or low-polluting, as specified in the new European design criteria for the indoor environment CEN CR 1752 (1998). The pollution source was a 20-year-old used carpet which was introduced on a rack behind a screen so that it was invisible to the occupants. Five groups of six female subjects each were exposed to the conditions in the office twice, once with the pollution source present and once with the pollution source absent, each exposure being 265 min in the afternoon, one group at a time. They assessed the perceived air quality and SBS symptoms while performing simulated office work. The subject-rated acceptability of the perceived air quality in the office corresponded to 22% dissatisfied when the pollution source was present, and to 15% dissatisfied when the pollution source was absent. In the former condition there was a significantly increased prevalence of headaches (P= 0.04) and significantly lower levels of reported effort (P=0.02) during the text typing and calculation tasks, both of which required a sustained level of concentration. In the text typing task, subjects worked significantly more slowly when the pollution source was present in the office (P=0.003), typing 6.5% less text than when the pollution source was absent from the office. Reducing the pollution load on indoor air proved to be an effective means of improving the comfort, health and productivity of building occupants.

Notes: Abstract In the past two decades, a group of health problems related to the indoor environment – generally termed sick building syndrome (SBS) – has emerged. We present an investigation of SBS in employees of a ministry working in a naturally ventilated office building that formerly had been used by a pharmaceutical company. A preceding environmental monitoring had failed to identify the cause(s) for the complaints. We conducted a questionnaire-based investigation and categorized the building sections and rooms according to their renovation status and their former use, respectively. The highest level of complaints was found among the employees working in rooms that in the past had been used for the production or storage of various pharmaceutical products suggesting that pharmaceutical odors may be a risk factor for SBS. Clinical laboratory tests did not show any unusual results. We conclude that the former use of a building for production and storage of pharmaceutical products should be considered as a possible risk factor for complaints about indoor air quality, e.g., when advising about or planning for renovations of buildings formerly used for production, handling, or storing of chemicals.

Notes: Abstract Latex paints are widely used in residential and commercial indoor environments. The surface areas covered by the paints in these environments are relatively large. Thus, latex paints have the potential for having a major impact on indoor air quality (IAQ). A study was undertaken to develop methods for evaluating the impact of latex paint emission on IAQ. Small chamber experiments using stainless steel and painted and unpainted gypsum board substrates were conducted to determine the emission characteristics of latex paint. The emissions from the stainless steel were relatively short lived (3 to 4 days), whereas the emissions from gypsum board lasted for over 200 days. Because gypsum board is a common substrate for latex paint, all emission models were developed for the gypsum board substrates. The data from the small chamber tests led to the development of two empirical and two mass-transfer-based source emission models. Approximately 100 to 200 days of data were required to estimate the parameters required for the empirical models. Only 8 days of data were required to estimate the parameters for the mass-transfer-based models. The final models use paint formulation and mass transfer correlations to predict the emissions of the major individual volatile organic compounds emitted by latex paint.

Notes: Abstract To investigate the biological contaminant levels inside dwellings in Japan, the authors measured fungal indices, airborne mite allergens (Der 1 and Der 2), and suspended particulate matter (SPM). Measurements were continuously conducted at one dwelling located in Yokosuka-city, Kanagawa. The biosensors for fungal index were set at 12 points inside and 2 points outside the dwelling. An SPM sampler was placed in the living room, and samplers for collecting allergens were placed in the living room and in the washroom. The peak level of the fungal index was recorded during July, which is the rainy season in Japan. The highest value in the dwelling was 6.9 in the toilet, and the second highest was 6.6 near a window in the living room that faces southeast, and behind the sofa. The highest monthly SPM level was 21.5 μg/m3 during October, and the highest monthly allergen level (Der 1) in the living room was 25.7 μg/m3 during November. A positive relationship between the fungal index and mite allergens was not observed, and the levels of contaminants were not as those found in other studies. However, further study to investigate the distribution of biological contaminants is needed because indoor temperature and relative humidity are comparatively high.

Notes: Abstract The indoor environment of 80 houses in the Latrobe Valley, Victoria, Australia was assessed during six visits performed bi-monthly over a period of one year. Children between 7 and 14 years of age residing in the houses were included, resulting in 148 study children, 53 of whom were asthmatic. A respiratory health questionnaire was completed and skin prick tests performed. Significant risk factors for asthma were: exposure to a gas stove (OR=3.15, 95% CI 1.28-7.72), and indoor pets (OR = 2.68, 95% CI 1.07-6.70). Exposure to airborne Aspergillus spores (+10 CFU/m3, OR=1.51, 95% CI 1.05-2.18) was a risk factor for atopy, while exposure to a gas stove (OR=2.32, 95% CI 1.04-5.18) was a risk factor for respiratory symptoms. In conclusion, exposure to gas stoves, fungal spores and pets in the home were identified as statistically significant risk factors for respiratory health in children.

Notes: 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.

Notes: 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.

Notes: Abstract Numerous ground-coupled air systems have been constructed in combination with heat recovery units in mechanically ventilated buildings in Switzerland. The objective of this study was to investigate the microbial content within these ventilation systems and to monitor the quality of the air supply. The concentrations and the types of microorganisms in the outdoor air, in the air of the pipes and in the supply air of twelve ground-coupled air systems were determined. In addition, three buildings were examined four times a year to cover seasonal changes. In general, the concentrations of fungal spores and bacteria in the air at the end of the underground pipes were lower than in the outdoor air, but great differences were observed between ventilation systems of large buildings and one-family houses. Occasionally, an increase in the concentration of Penicillium, Aspergillus or Actinomycetes was noted within a piping system. The concentrations in the supply air behind the filters were always low. Based on these investigations, the operation of ground-coupled air systems can be recommended as long as regular controls are undertaken and cleaning facilities are available.

Notes: 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.

Notes: 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.

Notes: Abstract The growth-dependent production of known and new potential tracer compounds for moulds of the genus Penicillium on pine wood is shown. The analytical method used involves diffusive sampling by an adsorbent tube (Tenax-TA), thermal desorption, gas chromatography and a mass selective detector. Mass spectra of identified and unidentified potential tracer compounds are presented. Identified compounds are l-Octene-3-ol, 2-Heptanone, 4-Allylanisole and 3-Methyl-l-butanol. In addition, several other compounds were tentatively identified or recognized in different samples by their retention time and mass spectra. The microbiologically produced volatile organic compounds (MVOC) are produced during different time periods of the mould growth cycle. The impact of these results on screening measurements for houses with mould problems is discussed together with the applicability and need for new and more tracer compounds for mould growth in buildings.

Notes: Abstract A study was conducted to characterize the indoor environment of a multifloor, multiuse, nonproblem, noncompliant building through long-term monitoring for biological, chemical, and particulate pollutants. The study also assessed the effects of cleaning on indoor air quality by providing a program to monitor baseline levels, providing a rigorous (deep) cleaning of the building, and then continuing to monitor after implementation of a standardized, improved, cleaning program. To assess the effectiveness of the cleaning program, air, surface, and dust data from monitoring prior to the cleaning program were compared with those obtained while the improved housekeeping program was in place. Correlations between pollutants and other environmental factors were studied. The data suggest that the improved cleaning program contributed to indoor air quality through the reduction of airborne dust mass, total volatile organic compounds, and culturable bacteria and fungi.

Notes: Abstract The literature for the control of dust mites by modification of the psychrometric conditions of the environment is reviewed from the standpoint of a building scientist or engineer, both to present to building science workers an envelope of micro-environment psychrometric conditions to use as control, and to highlight those areas of dust mite biology that require further research to complete the knowledge of the psychrometric envelope for dust mite viability. Some important data to allow tight specification of psychrometric control conditions are missing, viz.: the temperature dependence of critical equilibrium activity for Dermatophagoides pteronyssinus and Euroglyphus maynei; behaviour of dust mite populations under a fluctuating climate; and the difference between wild and laboratory populations. The widely quoted figure for dust mite control of 7 g/mg absolute humidity should be used with caution.

Notes: Abstract The sensory pollution load and microbial contamination of glass-fibre filters at high and low relative humidity were investigated in an experimental set-up in the laboratory. Dust and particles from the outdoor air were collected in two EU7 glass-fibre filters for a pre-conditioning period of 16–18 weeks during which there was a constant airflow with a velocity of 1.9 m/s through the filters. One of the filters was exposed to outdoor air of approximately 40% relative humidity and 10°C, the other to outdoor air of approximately 80% relative humidity and 5°C. The dust in ventilation filters can constitute a serious pollution source in the indoor environment, causing deterioration in the quality of the supply air even before it enters the ventilated spaces. The sensory pollution load from the used filters after the continuous operating time of 16–18 weeks was significantly higher than the sensory pollution load from new filters but the sensory load at 40% and 80% relative humidity did not differ. The microbial contamination of the supply air downstream of the filters, which on average had been exposed to outdoor air of 40% and 80% relative humidity, was negligible.

Notes: Abstract Several airflow and contaminant dispersion models have been developed to study air distribution in buildings. This paper reports the results of a comprehensive validation of two models: COMIS and CONTAM. The validation process was carried out at three different levels; inter-program comparison; validation with experimental data which was collected in a controlled environment; and finally, validation with field measurement data. At the inter-program level, the airflow rates and pressure values predicted by COMIS and CONTAM for a four-zone paper building were compared with the airflow rates and pressures predicted by CBSAIR, AIRNET and BUS. The results show good agreement between these software programs.The second level of validation compares the models’ predictions with measured data collected in a controlled environment. Fan pressurisation, smoke and tracer gas tests were conducted to estimate the permeability of building envelope components, to locate cracks, and to determine the interzonal airflow rates between rooms. The results confirm that there is good agreement between predictions made by COMIS and CONTAM; there are, however, some differences between these models’ predictions and the measured data.The predictions made by these models were also compared with the results of a tracer gas measurement carried out in a residential building. The predicted and measured values were in good agreement.

Notes: Abstract Building characteristics of dwelling units in the metropolitan Boston area were statistically sorted on the basis of observed associations between the variables. First, associations between categories of house characteristics were determined by cross-table analyses with a pair-wise chi-square test. The key characteristics, which have a significant relationship with many other characteristics, were used to classify the dwelling units into several groups. Two key characteristics, i.e. building type and size of building, were determined. Houses were divided into three groups: single-unit building, small multi-unit (2 to 4 units) building, and large multi-unit (5+ units) building. The building type was not associated with indoor source, but was significantly associated with volume of dwelling unit, air exchange rate, and indoor and outdoor NO2 concentrations. Lower airflow, smaller volume units, and higher outdoor NC2 concentrations, in combination with other factors, result in higher indoor NO2 concentrations in multi-dwelling residential units (apartments and condominiums).

Notes: Abstract The impact on air quality of the emission of pollutants from freshly conditioned sealant and waterborne paint, and a new carpet was investigated by means of a closed emission system and a high loading factor, i.e. “maximized” test conditions. VOCs were measured. Speciated TVOC values obtained by summation of single VOCs and TVOC (cyclohexane equivalents) values determined by IR spectroscopy were of the same order of magnitude for the carpet and for the sealant. Biological evaluation of the effects of the VOCs was undertaken from the concentrations and the odour and irritation thresholds of each substance. The overall agreements and the mutual supplementation of the results from the TVOC and biological evaluations were apparent, suggesting that both approaches should be part of the evaluation of emissions from building materials. Also the mouse bioassay (ASTM, 1984) was used for evaluation of the irritants emitted. Chemical emission testing and the use of established lists of irritation thresholds appear to be more cost-effective, due to the low sensitivity of the bioassay. This approach was demonstrated with 2-butanone oxime (emitted from the sealant). The same type of approach may be used in relation to odour and hazard identification. However, human and animal tests are necessary in cases where biological data are lacking or where the chemical emission is unknown.

Notes: Abstract Measured emissions from building materials (Part I, Nielsen et al., 1996), were evaluated for their sensory effects, odour and irritation, as well as for health effects. The procedures adopted are general. First, if established indoor air standards or guidelines are available, they are to be preferred for the evaluations. Second, if they are not available, odour and irritation thresholds are used. The occupational exposure limits may be used for the evaluation of health effects if applying an additional safety factor between 4 and 40. The actual value depends on the critical effect, but a safety factor of 40 is proposed as a first approximation. Other values must be justified. Third, if occupational exposure limits are not available, two different procedures provide a tentative standard or guideline on the basis of published literature, which of necessity must therefore be collected and evaluated. One procedure estimates the standard from an effect in animals and applies a number of safety factors (each often equal to 10), corresponding to a series of worst-case assumptions. The other procedure evaluates the critical effect and uses fewer specific safety factors to predict the human no-observed-effect level (NOEL). The political safety factor is then determined, i.e. how far below the NOEL the standard or guideline level should be set. The last-mentioned procedure gives a logical concordant system, explaining why different standards or guidelines may be set for outdoor, indoor and occupational exposures, and why exposures exceeding a standard or a guideline need not cause health effects.

Notes: A method is described for the identification and quantification of compounds emitted into indoor air. In this method we have selected certain compounds from among the many emitted by various sources to perform as standards in screening the quality of the indoor air sample. Identification and quantification of the compounds found in a sample are made with a two-channel high resolution gas chromatograph with two FIDs. Identification is based on linear retention indexes. For comparison, the TVOC of the air sample is calculated in two different ways. This method allows rapid identification and quantification of the main compounds present in indoor air if the VOC air mixture is not too complex.

Notes: Results of a questionnaire survey of 939 workers from 5 air-conditioned offices where smoking was prohibited are reported. Levels of carbon monoxide, carbon dioxide, formaldehde, respirable particulates, and temperature, relative humidity, and illuminance were measured in these buildings, but these did not correlate with symptom reports. The number of sick building syndrome symptoms per worker was related linearly to perceived indoor air quality, job stress, job satisfaction, allergies, eyewear, and seasonal affective disorder. Two hundred and fifty five of these workers also completed a battery of psychological measures. Measures of depression, personality variables, situational stress, vulnerability to stress, and individual differences in circadian rhythms did not correlate with the numbers of sick building syndrome symptoms per worker, although depression did correlate with the number of symptoms when these were weighted for their frequency of occurrence in the previous month. Job stress and perceptions of indoor air quality correlated with both the unweighted and weighted indices of sick building syndrome.

Notes: The prevalence of irritative symptoms and the incidence of respiratory infections among children in a day-care center affected by mold were compared with those in a reference day-care center. A retrospective pilot study was made in the mold-problem day-care center. Analysis of absenteeism records and a one-year follow-up study were made in both day-care centers. In the pilot study, half of the exposed 41 children had prolonged or frequent symptoms and respiratory infections. In addition, the absenteeism in the mold-problem day-care center was nearly twice as high as in the reference day-care center. After cessation of the exposure, the occurrence of respiratory symptoms decreased and no lower respiratory tract infections appeared.

Notes: The hygienic properties of two types of processing oils used in the manufacture of galvanised metal air ducts mere investigated. One of the oils was based on mineral oil and the other on vegetable oil. Evaporation of the oil emulsions from the galvanized metal surface was followed for ten months, after which the water-binding capacity of the residues was measured in increasing and decreasing RH at the range of 75-100%. The potential of processing oil residues to act as nutrients for fungi was tested with Penicillium brevi-compactum in the laboratory. The odour emission of oil residues was evaluated with the aid of a trained panel for eight months. After the ten months, the residue of mineral-oil- and vegetable-oil-based products was 60% and 79% of the original amount, respectively. Both oils were able to absorb water but desorption of the water from vegetable-oil-based products was delayed, thus increasing the risk of fungal growth. The residues of both oils provided sufficient nutrients for fungal growth. The odour emissions from the oil residues were high and that of vegetable oil tended also to increase. To attain high indoor air quality, duct manufacturing methods which do not leave residues should be developed.

Notes: Environmental tobacco smoke (ETS) has been identified as one of the factors associated with the symptoms of the sick building syndrome (SBS). We investigated the role of ETS in an office building during the phased introduction of a smoking ban. Over a two-year period we measured symptoms using a validated questionnaire, environmental nicotine levels and salivary cotinine as a biological marker of nicotine absorption in a stratified systemic sample of 375 office employees (91% response rate). In addition, 26 persons from a non-smoking office were studied as a control group. This report describes the findings derived from a cross-sectional analysis of the initial baseline data. Amongst the validated nonsmokers, symptoms increased with increasing nicotine exposure from ETS (r= 0.165 p 〈 0. 01), supporting the role of ETS in the SBS. Smokers reported significantly fewer symptoms than non-smokers, as has been found before, but were exposed to higher levels of airborne nicotine as expected. We suggest that this factor, along with the misclassification of smoking status, may have obscured an association between ETS exposure and the SBS in previous studies. An analysis of the findings after implementation of the smoking ban should provide further information on how much of the SBS is attributable to ETS in this study population.

Notes: Abstract This paper reviews current literature on the associations of ventilation rates and carbon dioxide concentrations in non-residential and non-industrial buildings (primarily offices) with health and other human outcomes. Twenty studies, with close to 30,000 subjects, investigated the association of ventilation rates with human responses, and 21 studies, with over 30,000 subjects, investigated the association of carbon dioxide concentration with these responses. Almost all studies found that ventilation rates below 10 Ls-1 per person in all building types were associated with statistically significant worsening in one or more health or perceived air quality outcomes. Some studies determined that increases in ventilation rates above 10 Ls-1 per person, up to approximately 20 Ls-1 per person, were associated with further significant decreases in the prevalence of sick building syndrome (SBS) symptoms or with further significant improvements in perceived air quality. The carbon dioxide studies support these findings. About half of the carbon dioxide studies suggest that the risk of sick building syndrome symptoms continued to decrease significantly with decreasing carbon dioxide concentrations below 800 ppm. The ventilation studies reported relative risks of 1.5–2 for respiratory illnesses and 1.1–6 for sick building syndrome symptoms for low compared to high low ventilation rates.

Notes: Abstract A European project started at the end of 1992, in which, in addition to current methods, trained sensory panels were used to investigate office buildings all over Europe. The main aim of this EC-Audit was to develop assessment procedures and guidance on ventilation and source control, to help optimize energy use in buildings while assuring good indoor air quality.In each of nine countries, six or more office buildings were selected. Measurements were performed at five selected locations in each building. The buildings were studied while normally occupied and ventilated to identify the pollution sources in the spaces and to quantify the total pollution load caused by the occupants and their activities, as well as the ventilation systems. The investigation included physical and chemical measurements, assessment of the perceived air quality in the spaces by a trained sensory panel, and measurement of the outdoor air supply to the spaces. A questionnaire for evaluating retrospective and immediate symptoms and perceptions was given to the occupants of the buildings. The building characteristics were described by use of a check-list. The annual energy consumption of the buildings and the weather conditions were registered.This paper presents results and conclusions of the audit in 56 buildings in Europe. However, the analysis and discussions of the results are a summary of the work done, and are focused mainly on comparison between sensory assessments and the other measurements performed.Furthermore, this paper brings the results of the study based on a two-factor analysis. A paper dealing with results on a multifactorial analysis is in preparation.

Notes: Abstract Sources of indoor air pollutants in residential and office environments can be managed to reduce occupant exposures. Techniques for managing indoor air pollution sources include: source elimination, substitution, modification, pretreatment, and altering the amount, location, or time of use. Intelligent source management requires knowledge of the source's emission characteristics, including chemical composition, emission rates, and decay rates. In addition, knowledge of mechanical and natural outdoor air exchange rates, heating/air-conditioning duct flow rates, and local exhaust fan (e.g., kitchen, bathroom) flow rates is needed to determine pollutant concentrations. Finally, indoor air quality (IAQ) models use this information and occupant activity patterns to determine instantaneous and/or cumulative individual exposure. This paper describes a number of residential and office scenarios for various indoor air pollution sources, several ventilation conditions, and typical occupant activity patterns. IAQ model predictions of occupant exposures for these scenarios are given for selected source management options. A one-month period was used to compare exposures; thus, long-term exposure information is not presented in this paper.

Notes: Abstract We have developed a simplified analytical indoor air model that describes the concentrations as a function of position and time in a room following a short-term release of airborne particles or gases. The indoor dispersion model considers the two main physical processes of (1) point-source dispersion with reflection from all walls and (2) the general concentration decay in a room due to room ventilation and surface deposition of pollutants. Comparison of model predictions with experimental indoor measurements conducted by other researchers showed excellent agreement. This model should prove useful for human-health risk estimations in which the inhalation dose resulting from an indoor, short-term release of a contaminant needs to be calculated.

Notes: Abstract This paper presents data on indoor air quality in schools as perceived by those working in them and relates these data to exposure measurements. Data on subjective air quality, domestic exposures and health aspects were gathered by means of a questionnaire which was sent to all personnel in 38 schools; it was completed by 1410 persons (85’4 of the total). Data on exposure were gathered by exposure measurements in classrooms. The results indicate that 53% of the personnel perceived the indoor air quality as bad or very bad. It was perceived as worse by those who were younger, those who were dissatisfied with their psychosocial work climate and those who were not exposed to tobacco smoke at home. In older school buildings and buildings with displacement ventilation there was less dissatisfaction with the air quality. There were no significant relations between complaints and air exchange rate or concentration of carbon dioxide. The air quality was perceived as worse at higher levels of exposure to a number of airborne compounds including volatile organic compounds, moulds, bacteria and respirable dust. It was concluded that exposure to indoor pollutants affects perception even at the low concentrations normally found indoors in nonindustrial buildings.