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Carbon dioxide (CO 2 ) is an important environmental parameter in aircraft cabins. To understand the most recent, real-time CO 2 concentration levels and their key influencing factors in aircraft cabins, we conducted in-flight measurements of 52 randomly selected commercial flights with different aircraft types and durations from August 2017 to August 2019. The spatial temporal characteristics of CO 2 concentrations on board were analyzed and summarized. For the flight time scale, the CO 2 concentrations during the boarding phase (1680 ± 558 ppmv) were notably higher than that in other phases, whereas the condition of the cruising phase was the lowest in most flights. The flight average CO 2 concentrations of the cruising phase were 1253 ± 164 ppmv, and the corresponding estimated outside airflow rates were 6.2 ± 1.3 L/s/p in the economy class across all flights. Single-aisle and twin-aisle flights did not show noticeable differences for the same phases. Relatively uniform CO 2 concentrations were observed at different positions of the same class. By comparing the results of this study with those previously reported, CO 2 concentrations showed a slightly decreasing trend over the last 30 years. This suggested a slightly increased ventilation rate and potentially superior air quality on board., (© 2021 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Ambient fine particulate matter (PM 2.5 ), as one of the predominant air pollutants, has achieved effective control in recent years in China. Whether the use of indoor air purifiers is still necessary needs further exploration. A randomized crossover trial was conducted in 54 healthy students in Beijing, China. Participants were randomized assigned to the use of real or sham high-efficiency particulate air filter (HEPA) for a week and changed the status after a washout period. Health measurements of cardiorespiratory biomarkers were performed at the end of each period. Linear mixed-effects models were used to evaluate the association between PM 2.5 exposure and cardiorespiratory biomarkers. Compared with sham air purification, average diastolic blood pressure (DBP), fractional exhaled nitric oxide (FeNO), and 8-isoprostane (8-isoPGF2α) levels decreased significantly in the real purification. The effects of indoor air purification on lung function indicators including forced expiratory volume in one second (FEV 1 ), peak expiratory flow (PEF), and forced expiratory flow between the 25th and 75th percentile of forced vital capacity (FEF 25%-75% ) were also significant. Our findings showed a protective effect of indoor HEPA air purifiers on cardiorespiratory health of young healthy adults reflected by the decreased blood pressure, respiratory inflammation, and systematic oxidative stress and improved lung function., (© 2021 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

PM 10 -bound polycyclic aromatic hydrocarbons (PAHs) levels were monitored at urban locations (outdoor/indoor) within the city of Madrid between May 2017 and April 2018. Fourteen PAH congeners were measured, potential emission sources were identified as were potential carcinogenic risks. The ΣPAHs averaged 0.577 and 0.186 ng/m 3 in outdoor and indoor air, with a high linear correlation per individual mean PAH and month. The largest contributors to the ΣPAHs were the high-molecular-weight PAHs. Principal component analysis-multiple linear regression results showed that emissions from diesel and vehicular processes explained 27% and 23% of the total variance of outdoor and indoor air, while combustion processes accounted for 30% and 25% in ambient and indoor air, respectively. During the cold season, biomass burning plus coal and wood combustion were additional sources of outdoor emissions. The heavy-, medium- and light-molecular-weight PAH originating from outdoor sources accounted for 72%, 80%, and ~60% of the indoor levels of the three respective PAH groups. Average BaP concentration was 0.029 and 0.016 ng/m 3 in outdoor and indoor air, respectively. Estimated BaPeq concentration averaged 0.072, 0.035, and 0.027 ng/m 3 for outdoor, indoor, and indoor-generated individual PAH concentrations, respectively. The estimated carcinogenic risk falls within the range of acceptable risk targeted by the US-EPA., (© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Airborne transmission of infectious diseases through air travel has become a major concern, especially during the COVID-19 pandemic. The flying public and crew members have long demanded better air quality and thermal comfort in commercial airliner cabins. This paper reviewed studies related to the airliner cabin air environment that have been published in scientific journals since 2000, to understand the state-of-the-art in cabin air environment design and the efforts made to improve this environment. In this critical review, this paper discusses the challenges and opportunities in studying the cabin air environment. The literature review concluded that current environmental control systems for airliner cabins have done little to stop the airborne transmission of infectious diseases. There were no reports of significant air quality problems in cabins, although passengers and crew members have complained of some health-related issues. The air temperature in cabins needs to be better controlled, and therefore, better thermal comfort models for airliners should be developed. Low humidity is a major complaint from passengers and crew members. Gaspers are used by passengers to adjust thermal comfort, but they do not improve air quality. Various personalized and displacement ventilation systems have been developed to improve air quality and thermal comfort. Air cleaning technologies need to be further developed. Good tools are available for designing a better cabin air environment., (© 2022 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

The article announces some recipients awards presented by the ISIAQ Academy of Fellows at the 13th International Conference on Indoor Air Quality and Climate on July 7 to 12, 2014 including the Yaglou Awards for Gabriel Bekö, the Pettenkofer Award for Charles J. Weschler and some winning papers.

The rapid development of automated measurement equipment enables researchers to collect greater quantities of time-resolved data from indoor and outdoor environments. While significant, the interpretation of the resulting data can be a time-consuming effort. This paper introduces an automated process of interpreting PM2.5 time-resolved data and differentiating PM2.5 emissions resulting from indoor and outdoor sources. We use Random Forest (RF), a machine learning approach, to study a dataset of 836 indoor emission events that occurred over a 2-week period in 18 apartments in California. In this paper, we show model development and evaluate its performance as the sample size and source vary. We discuss the characteristics of the dataset that tended to help the source identification and why. For example, we show that data from many events and from different apartments are essential for the model to be suitable for analyzing a new separate dataset. We also show that longitudinal data appear to be more helpful than the time frequency of measurements within a given apartment. We use the resulting RF model to analyze PM2.5 data of an entirely separate dataset collected from 65 new homes in California. The RF model identifies 442 indoor emission events, with only a few misidentifications.

Indoor air pollution (IAP) is a recognized risk factor for various diseases. This paper examines the role of indoor solid fuel exposure in the risk of mycobacterium tuberculosis (TB) in Delhi Metropolitan, India. Using a cross‐sectional design, subjects were screened for a history of active TB and lifelong exposure to IAP sources, such as solid fuel burning and kerosene. The TB prevalence rate in the study area was 1117 per 100 000 population. Every year, increase in solid fuel exposure was associated with a three percent higher likelihood of a history of active TB. Subjects exposed to solid fuel and kerosene use for both heating home and cooking showed significant associations with TB. Age, household expenditure (a proxy of income), lung function, and smoking also showed significant associations with TB. Smokers and solid fuel–exposed subjects were four times more likely to have a history of active TB than non‐smoker and unexposed subjects. These finding calls strategies to mitigate solid fuel exposure, such as use of clean cookstove and ventilation, to mitigate the risk of TB which aligns with the United Nations' goal of "End TB by 2030." [ABSTRACT FROM AUTHOR]

The scientific literature through 2005 on the effects of ventilation rates on health in indoor environments has been reviewed by a multidisciplinary group. The group judged 27 papers published in peer-reviewed scientific journals as providing sufficient information on both ventilation rates and health effects to inform the relationship. Consistency was found across multiple investigations and different epidemiologic designs for different populations. Multiple health endpoints show similar relationships with ventilation rate. There is biological plausibility for an association of health outcomes with ventilation rates, although the literature does not provide clear evidence on particular agent(s) for the effects. Higher ventilation rates in offices, up to about 25 l/s per person, are associated with reduced prevalence of sick building syndrome (SBS) symptoms. The limited available data suggest that inflammation, respiratory infections, asthma symptoms and short-term sick leave increase with lower ventilation rates. Home ventilation rates above 0.5 air changes per hour (h-1) have been associated with a reduced risk of allergic manifestations among children in a Nordic climate. The need remains for more studies of the relationship between ventilation rates and health, especially in diverse climates, in locations with polluted outdoor air and in buildings other than offices. [ABSTRACT FROM AUTHOR]

Indoor pollutions jeopardize human health and welfare and may even cause serious morbidity and mortality under extreme conditions. To effectively control and improve indoor environment quality requires immediate interpretation of pollutant sensor readings and accurate identification of indoor pollution history and source characteristics (e.g. source location and release time). This procedure is complicated by non-uniform and dynamic contaminant indoor dispersion behaviors as well as diverse sensor network distributions. This paper introduces a probability concept based inverse modeling method that is able to identify the source location for an instantaneous point source placed in an enclosed environment with known source release time. The study presents the mathematical models that address three different sensing scenarios: sensors without concentration readings, sensors with spatial concentration readings, and sensors with temporal concentration readings. The paper demonstrates the inverse modeling method and algorithm with two case studies: air pollution in an office space and in an aircraft cabin. The predictions were successfully verified against the forward simulation settings, indicating good capability of the method in finding indoor pollutant sources. The research lays a solid ground for further study of the method for more complicated indoor contamination problems. Practical Implications The method developed can help track indoor contaminant source location with limited sensor outputs. This will ensure an effective and prompt execution of building control strategies and thus achieve a healthy and safe indoor environment. The method can also assist the design of optimal sensor networks. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a review and assessment of aircraft cabin air quality studies with measured levels of volatile and semivolatile organic compounds (VOCs and SVOCs). VOC and SVOC concentrations reported for aircraft cabins are compared with those reported for residential and office buildings and for passenger compartments of other types of transportation. An assessment of measurement technologies and quality assurance procedures is included. The six studies reviewed in the paper range in coverage from two to about 30 flights per study. None of the monitored flights included any unusual or episodic events that could affect cabin air quality. Most studies have used scientifically sound methods for measurements. Study results indicate that under routine aircraft operations, contaminant levels in aircraft cabins are similar to those in residential and office buildings, with two exceptions: (1) levels of ethanol and acetone, indicators of bioeffluents and chemicals from consumer products are higher in aircraft than in home or office environments, and (2) levels of certain chlorinated hydrocarbons and fuel-related contaminants are higher in residential/office buildings than in aircraft. Similarly, ethanol and acetone levels are higher in aircraft than in other transportation modes but the levels of some pollutants, such as m -/p -xylenes, tend to be lower in aircraft. Practical Implications This paper reviews measured air concentrations of organic contaminants in the aircraft cabin and supply air. These concentrations are compared with those reported for buildings and other transportation modes such as buses. Although such assessments are not conclusive and some differences exist between aircraft and other environments, the measured concentrations of organics are low. [ABSTRACT FROM AUTHOR]

Abstract Recent studies have shown that surface and gaseous contaminant interactions may play an important role in indoor air quality. Modeling is an important tool to improve our knowledge about the phenomena involved and define appropriate ventilation strategies. However, data for sorption isotherms and diffusion in building materials remain woefully lacking. This paper deals with the latter point. It aims at investigating a methodology based on an analysis of the material porosity first and then the application of Carniglia's mathematical model to determine the effective diffusivity of gaseous species in building materials. This methodology, whose main principles are presented in the first part of the paper, was applied to seven commonly found materials. Mercury intrusion porosimetry (MIP) tests, and the calculations using Carniglia's model, reveal typical total porosities and tortuosity factors for these materials. The analysis of pore size distributions (PSDs) also draws one's attention to the possible differences in the pore structures that may exist between two samples of the same type of material and the differences in the effective diffusivities of contaminants that may result from them. The computed effective diffusivities were subsequently compared to data from experiments carried out in the frame of the EC project MATHIS. An agreement was obtained, thus validating Carniglia's methodology – a methodology that offers many practical advantages compared to diffusion-cell methods. Practical Implications The knowledge of effective diffusivities of contaminants in building materials is of central importance when modeling surface and contaminant interactions in indoor air quality (IAQ) simulation. The method discussed in the paper enables one, in principle, to determine the diffusivities of any species in any material from porosity tests. It requires little experimental effort compared to commonly used methodologies. [ABSTRACT FROM AUTHOR]

People are an important source of pollution indoors, through activities such as cleaning, and also from "natural" emissions from breath and skin. This paper investigates natural emissions in high‐occupancy environments. Model simulations are performed for a school classroom during a typical summer in a polluted urban area. The results show that classroom occupants have a significant impact on indoor ozone, which increases from ~9 to ~20 ppb when the pupils leave for lunch and decreases to ~14 ppb when they return. The concentrations of 4‐OPA, formic acid, and acetic acid formed as oxidation products following skin emissions attained maximum concentrations of 0.8, 0.5, and 0.1 ppb, respectively, when pupils were present, increasing from near‐zero concentrations in their absence. For acetone, methanol, and ethanol from breath emissions, maximum concentrations were ~22.3, 6.6, and 21.5 ppb, respectively, compared to 7.4, 2.1, and 16.9 ppb in their absence. A rate of production analysis showed that occupancy reduced oxidant concentrations, while enhancing formation of nitrated organic compounds, owing to the chemistry that follows from increased aldehyde production. Occupancy also changes the peroxy radical composition, with those formed through isoprene oxidation becoming relatively more important, which also has consequences for subsequent oxidant concentrations. [ABSTRACT FROM AUTHOR]

A method was developed to analytically distinguish between the ventilated (v) and nonventilated (nv) fractions of water‐soluble ions in deposits of particle indoors. The indicative method was based on low‐cost passive outdoor and indoor sampling of the particle and ion deposits and NO2 gas and analysis of the regression values and residuals of the correlations between these parameters. The method was applied to measurements in the Pieskowa Skała Castle Museum in Poland. A dominating source of "soil and building dust" was indicated all year round, probably partly from renovation works of the castle, with larger total infiltration in the winter–spring (W‐S) but with a higher proportion of ventilation ingress in the summer–autumn (S‐A). About 60%–80%, by mass, of the water‐soluble ions in the soil and building dust were calcium and probably some magnesium bicarbonate (Ca(HCO3)2, Mg(HCO3)2) and about 10%–20% sulfates (SO4−−) with calcium (Ca++) and several other cations. The other main source of the ion deposits was indicated to be air pollution, with chloride (Cl−), sulfate (SO4−−), and nitrate (NO3−), from outdoor combustion sources, like traffic, residential heating, and industry. These were mainly v from outdoors in the colder parts of the year, but also to the more open locations in the S‐A. A small source of nv sulfate (SO4−−) was identified inside two showcases in the S‐A. The study showed good enclosure protection of the museum objects against exposure to particle pollution, but also the need to avoid the trapping of particle pollution inside showcases or closed rooms. The identification of the probable different amounts and sources of v and nv ions in the castle aided preventive actions to reduce the pollution exposure. [ABSTRACT FROM AUTHOR]

We use air pollution exposure measurements and household survey data from four studies conducted across three countries in sub‐Saharan Africa (SSA) to analyze the association between carbon monoxide (CO) exposure from cooking with biomass and indicators of cognitive impairment. While there is strong evidence on the relationship between ambient air pollution exposure and cognitive impairment from studies in high‐income countries, relatively little research has focused on household air pollution (HAP) in low‐income country settings where risks of HAP exposure are high. This study is the first to our knowledge to focus on the association between HAP exposure (specifically CO exposure) and cognitive impairment across diverse settings in SSA. We use 24‐hour measurements of primary cooks' exposure to CO across four study sites: urban Zambia (n = 493); urban Malawi (n = 130); rural Malawi (n = 102); and urban Rwanda (n = 2,576). We model the estimated percent carboxyhemoglobin (%COHb) of cooks and map values to a toxicological profile for risk of cognitive impairment. We find that across all study settings, cooks' average %COHb levels are below levels of daily concern, but that cooks who use charcoal for preparing greater than 40% of meals are more likely to spend additional time at higher levels of risk. For the urban Zambia sample, we compare %COHb and frequency of charcoal use to a series of cognitive test scores and find no consistent relationships between %COHb and cognitive test scores. High levels of daily CO exposure from cooks across SSA highlight the potential for longer‐term negative cognitive (and other) health outcomes motivating additional research and efforts to characterize and mitigate risk. [ABSTRACT FROM AUTHOR]

The level of exposure to human exhaled contaminants in a room depends not only on the air distribution system but also on people's different positions, the distance between them, people's activity level and height, direction of exhalation, and the surrounding temperature and temperature gradient. Human exhalation is studied in detail for different distribution systems: displacement and mixing ventilation as well as a system without mechanical ventilation. Two thermal manikins breathing through the mouth are used to simulate the exposure to human exhaled contaminants. The position and distance between the manikins are changed to study the influence on the level of exposure. The results show that the air exhaled by a manikin flows a longer distance with a higher concentration in case of displacement ventilation than in the other two cases, indicating a significant exposure to the contaminants for one person positioned in front of another. However, in all three cases, the exhalation flow of the source penetrates the thermal plume, causing an increase in the concentration of contaminants in front of the target person. The results are significantly dependent on the distance and position between the two manikins in all three cases. Practical Implications Indoor environments are susceptible to contaminant exposure, as contaminants can easily spread in the air. Human breathing is one of the most important biological contaminant sources, as the exhaled air can contain different pathogens such as viruses and bacteria. This paper addresses the human exhalation flow and its behavior in connection with different ventilation strategies, as well as the interaction between two people in a room. This is a key factor for studying the airborne infection risk when the room is occupied by several persons. The paper only takes into account the airborne part of the infection risk. [ABSTRACT FROM AUTHOR]

More than 30 years after the First International Indoor Climate Symposium, ten researchers from the USA, Slovakia, Sweden, and Denmark gathered to review the current status of indoor environmental research. We initiated our review with discussions during the 1-day meeting and followed that with parallel research and writing efforts culminating with internal review and revision cycles. In this paper, we present our choices for the most important research findings on indoor environmental quality from the past three decades followed by a discussion of the most important research questions in our field today. We then continue with a discussion on whether there are research areas for which we can 'close the book' and say that we already know what is needed. Finally, we discuss whether we can maintain our identity in the future or it is time to team up with new partners. [ABSTRACT FROM AUTHOR]

Multizone network models employ several assumptions, such as uniform temperature and pressure and quiescent air inside a zone, which may lead to inaccurate results in flow calculations. These assumptions can be eliminated in the zones, where the assumptions are inappropriate, by coupling a multizone network program with a computational fluid dynamics (CFD) program. Through theoretical analysis, this paper proves that the solution of air distribution by using the coupled program exists and is unique. Three possible coupling methods have been discussed in the paper. The best method is pressure–pressure coupling that exchanges pressure between the multizone and CFD because it is most stable and can always lead to a converged solution. Numerical tests were further performed to verify the theory and it demonstrated that the coupled program is able to effectively improve the accuracy of the results. Practical Implications The results of this paper provide a theoretical basis for improving the accuracy for modeling airflow and contaminant distributions in buildings. The coupled multizone and computational fluid dynamics can give high fidelity results, so field measurements may not be needed in the future. Designers of indoor environment in the future can use such a tool to evaluate different alternatives in design and identify the best solution for a building that can provide a healthy indoor environment. [ABSTRACT FROM AUTHOR]

Eye irritation is one of the most frequently reported symptoms in relation to working in office-like environments. So far, no consistent association has been found between concentration of airborne particles and prevalence of eye irritation. External physical factors not hitherto considered could have a large influence on particle deposition velocity onto the ocular surface. This may have obscured the role airborne particles play. Based on previously published semi-empirical models, the paper describes the influence of turbulence, gravitational settling, electrical fields, and thermophoresis on deposition velocity. A probabilistic approach was used to determine percentile ranges in deposition velocity when the magnitude of these parameters varied within typical ranges. The calculations suggest that differences in external factors other than particle size may cause differences in the deposition velocity of one order of magnitude or more. Studies trying to find associations between airborne particle concentration levels and eye irritation should take into consideration the influence of external physical factors on deposition velocity. External physical factors other than concentration are likely to have a large influence on the deposition rate of airborne particles onto the ocular surface. Thus, future studies on associations between airborne particle levels and eye symptoms should only be conducted if particle concentration measurements are suitably size resolved. Other relevant external physical factors should also be assessed and included in a multivariate analysis of exposure-response associations. [ABSTRACT FROM AUTHOR]

Abstract To assess the adverse health effects of volatile organic compounds (VOCs), epidemiological studies combine the health outcome of individuals with their concomitant VOC exposure. While the latter is representative of the studied period, health effects might also be the result of long-term exposure or emerge in consequence of a peak pollution throughout the year. To address these problems, additional information about the spatiotemporal distribution of VOCs is necessary. The present paper aims at elucidating the spatial and temporal variation of VOC concentrations in Leipzig, Germany. The analysis is based on 1499 indoor and 222 outdoor measurements taken in the period between 1994 and 2001. All data were collected in the frame of epidemiological studies (Diez et al., 1999; Fritz et al., 1998; Schulz et al., 1999). The analysis comprised concentrations of 30 VOCs belonging to the groups of alkanes, cycloalkanes, aromatics, volatile halogenated hydrocarbons, and terpenes. We found that the VOC load in indoor air is, on average, 10 times higher than outdoors. For the studied period there was a clear downward tendency for all VOCs in apartments in Leipzig, except for terpenes which show an upward trend in the period 1996–99. In indoor air we observe an annual cycle for the total VOC concentration as well as the sum concentrations of the above called groups. Highest concentrations occur during the winter months, approximately three times higher than the summer burden. We summarize this finding in a seasonal model, which is fitted to our measurements. Based on the model we develop a procedure for seasonal adjustment, which enables to roughly estimate the annual peak concentration utilizing one monthly observation. Practical Implications In indoor air the VOC burden varies seasonally. Concentrations are up to three times higher in winter compared with summer. For health risk assessment it is important to know the month of the VOC sampling. This paper presents a method, which can be used to normalize the results from VOC measurements taken at any time in the year (table with adjustment factors is given). [ABSTRACT FROM AUTHOR]

Personal thermal comfort models are a paradigm shift in predicting how building occupants perceive their thermal environment. Previous work has critical limitations related to the length of the data collected and the diversity of spaces. This paper outlines a longitudinal field study comprising 20 participants who answered Right-Here-Right-Now surveys using a smartwatch for 180 days. We collected more than 1080 field-based surveys per participant. Surveys were matched with environmental and physiological measured variables collected indoors in their homes and offices. We then trained and tested seven machine learning models per participant to predict their thermal preferences. Participants indicated 58% of the time to want no change in their thermal environment despite completing 75% of these surveys at temperatures higher than 26.6°C. All but one personal comfort model had a median prediction accuracy of 0.78 (F1-score). Skin, indoor, near body temperatures, and heart rate were the most valuable variables for accurate prediction. We found that ≈250-300 data points per participant were needed for accurate prediction. We, however, identified strategies to significantly reduce this number. Our study provides quantitative evidence on how to improve the accuracy of personal comfort models, prove the benefits of using wearable devices to predict thermal preference, and validate results from previous studies.

One major approach to modeling dispersion of pollutants inside confined spaces describes the turbulent transport of material as the product of an eddy diffusivity and the local concentration gradient. This paper examines the applicability of this eddy diffusivity/gradient model by (1) describing the conditions under which this approach is an appropriate representation of turbulent transport, and (2) re-analysis of data provided in studies that have successfully applied gradient transport to describe tracer concentrations. We find that the solutions of the mass conservation equation based on gradient transport provide adequate descriptions of concentration measurements from two studies representative of two types of sources: instantaneous and continuous release of aerosols. We then provide the rationale for the empirical success of the gradient transport model. The solutions of the gradient transport model allow us to examine the relationship between the ventilation rate and the spatial and temporal behavior of the dose of material associated with aerosol releases in a room. We conclude with the associated implications on mitigation of exposure to aerosols such as airborne virus or bacteria.

The health effects associated with exposure to ozone range from respiratory irritation to increased mortality. In this paper, we explore the use of three green building materials and an activated carbon (AC) mat that remove ozone from indoor air. We studied the effects of long-term exposure of these materials to real environments on ozone removal capability and pre- and post-ozonation emissions. A field study was completed over a 6-month period, and laboratory testing was intermittently conducted on material samples retrieved from the field. The results show sustained ozone removal for all materials except recycled carpet, with greatest ozone deposition velocity for AC mat (2.5-3.8 m/h) and perlite-based ceiling tile (2.2-3.2 m/h). Carbonyl emission rates were low for AC across all field sites. Painted gypsum wallboard and perlite-based ceiling tile had similar overall emission rates over the 6-month period, while carpet had large initial emission rates of undesirable by-products that decayed rapidly but remained high compared with other materials. This study confirms that AC mats and perlite-based ceiling tile are viable surfaces for inclusion in buildings to remove ozone without generating undesirable by-products. Practical implications The use of passive removal materials for ozone control could decrease the need for, or even render unnecessary, active but energy consuming control solutions. In buildings where ozone should be controlled (high outdoor ozone concentrations, sensitive populations), materials specifically designed or selected for removing ozone could be implemented, as long as ozone removal is not associated with large emissions of harmful by-products. We find that activated carbon mats and perlite-based ceiling tiles can provide substantial, long-lasting, ozone control. [ABSTRACT FROM AUTHOR]

The province of Lodi is located in northern Italy on the Po River plain, where high background levels of air pollutants are prevalent. Lodi province is characterized by intensive agriculture, notably animal husbandry. This paper assesses indoor levels of selected airborne pollutants in 60 homes in the province, with special attention to size-fractionated particulate matter (PM). Indoor PM2.5 concentrations are frequently higher than current guidelines. PM10 and nitrogen dioxide also exceed the respective guideline recommendations in some cases, noting that 24-h nitrogen dioxide levels were compared with an annual limit value. All other studied pollutant levels are below current international guidelines. Among indoor PM size fractions, PM0.5 is predominant in terms of mass concentrations corresponding to 57% of PM10 in summer and 71% in winter. A strong seasonal trend is observed for all studied pollutants, with higher levels in winter corresponding to changes in ambient concentrations. The seasonal variation in PM10 is largely due to PM0.5 increase from summer to winter. Summer indoor PM levels are mainly from indoor-generated particles, while particles of outdoor origin represent the main contribution to winter indoor PM levels. On average, indoor concentrations of coarse PM are mostly constituted by indoor-generated particles. Practical Implications This study presents a comparison between measured indoor concentrations in the study area and indoor air quality guideline criteria. Accordingly, particulate matter (PM) and NO2 are identified as key pollutants that may pose health concerns. It is also found that indoor PM in residential units is mainly constituted by particles with aerodynamic diameters <0.5 μm, especially in winter. Risk mitigation strategies should be focused on the reduction in indoor levels of NO2 and ultrafine and fine particles, both infiltrated from outdoors and generated by indoor sources. [ABSTRACT FROM AUTHOR]

In this study, we are trying to investigate the indoor air pollution and to estimate the residents’ pollution exposure reduction of energy altering in rural Tibet. Daily PM2.5 monitoring was conducted in indoor microenvironments like kitchen, living-room, bedroom, and yard in rural Tibet from December 2006 to March 2007. For kitchen air pollution, impact of two fuel types, methane and solid biomass fuels (SBFs), were compared. Questionnaire survey on the domestic energy pattern and residents’ daily activity pattern was performed in Zha-nang County. Daily average PM2.5 concentrations in kitchen, living-room, bedroom, and yard were 134.91 μg/m3 (mean, n = 45, 95%CI 84.02, 185.80), 103.61 μg/m3 (mean, n = 21, 95%CI 85.77, 121.45), 76.13 μg/m3 (mean, n = 18, 95%CI 57.22, 95.04), and 78.33 μg/m3 (mean, n = 34, 95%CI 60.00, 96.65) respectively. Using SBFs in kitchen resulted in higher indoor pollution than using methane. PM2.5 concentrations in kitchen with dung cake, fuel wood and methane use were 117.41 μg/m3 (mean, n = 18, 95%CI 71.03, 163.79), 271.11 μg/m3 (mean, n = 12, 95%CI 104.74, 437.48), and 46.96 μg/m3 (mean, n = 15, 95%CI 28.10, 65.82) respectively. Family income has significant influence on cooking energy choice, while the lack of commercial energy supply affects the energy choice for heating more. The effects of two countermeasures to improve indoor air quality were estimated in this research. One is to replace SBFs by clean energy like methane, the other is to separate the cooking place from other rooms and by applying these countermeasures, residents’ exposure to particulate matters would reduce by 25–50% (methane) or 20–30% (separation) compared to the present situation. Practical Implications Indoor air pollution caused by solid biomass fuels is one of the most important burdens of disease in the developing countries, which attracts the attention of environment and public health researchers, as well as policy makers. This paper gives a pilot research on the indoor air pollution and estimated the effects of some intervention policies in Tibet of China, where the living habits of the residents are quite different from other parts of the world. This work would be an important supply to the indoor air pollution studies, and would be helpful in policy making. [ABSTRACT FROM AUTHOR]

Quick information on airborne infectious disease transmission in airliner cabins is essential to reduce the risk of infection of passengers and crew members. This investigation proposed a one-dimensional analytical model that can predict the longitudinal transmission of airborne contaminants or disease viruses inside an airliner cabin. The model considered both diffusive and convective transport of contaminants in the longitudinal direction of the cabin but assumed complete mixing of contaminants in the cabin cross-section. The effect of recirculation of the cabin air and efficiency of the high-efficiency particulate air (HEPA) filters is also considered in the model. The analytical solution for the one-dimensional contaminant transport model is obtained by using the principle of superposition and the method of separation of variables. The analytical solutions agree well with the computational fluid dynamics (CFD) results. The coupling of a CFD model with the one-dimensional analytical model could capture the impact of local airflow on contaminant transport. This analytical model has been used for analyzing contaminant transport in a 30-row all-economy-class airliner cabin with minimal computing effort. Practical Implications The paper presents a new one-dimensional analytical model that can provide quick information on global airborne contaminant transmissions in airliner cabins for effective response plans. The model can be used to study the effects of air exchange rates, recirculation, efficiency of the high-efficiency particulate air (HEPA) filters and longitudinal airflow on airborne contaminant transport in airliner cabins with minimal computing effort. [ABSTRACT FROM AUTHOR]

Real-time flow simulation is crucial for emergency management in buildings, such as fire and accidental or intentional release of chemical/biological agents (contaminants). The simulation results can then be used to impose proper measures to minimize casualties. Computational fluid dynamics (CFD) is accurate, but too time-consuming. Nodal models are fast, but not informative. To obtain a quick and informative solution, this study proposes an intermediate approach between nodal models and CFD by introducing a fast fluid dynamics (FFD) method. This investigation used the FFD methods with and without turbulence treatments to study systematically four basic flows in buildings, and compared the numerical results with the corresponding CFD results and the data from the literature. The results show that, on one hand, the FFD can offer much richer flow information than nodal models, but less accurate results than CFD. On the other hand, the FFD is 50 times faster than the CFD. The results also show that the FFD with the laminar assumption has the best overall performance as regards both accuracy and speed. It is possible to conduct faster-than-real-time flow simulations with detailed flow information by using the FFD method. Practical Implications The paper introduces a fast fluid dynamics (FFD) method, which can simulate airflow and contaminant dispersion in buildings with real-time or faster-than-real-time speed and provide informative solutions. As an intermediate approach between nodal models and the computational fluid dynamics (CFD), the FFD can be a very useful tool for emergency management in case of fire and accidental or intentional release of chemical or biological agents in a building or around the buildings. The FFD can also be used as a preliminary test tool for quick assessment of indoor airflows before a detailed CFD analysis. [ABSTRACT FROM AUTHOR]

Fumes produced during frying have been implicated as a potential cause for the increased incidence of adenocarcinoma. Particulate matter exposure has also been linked with other pulmonary and coronary disease. This study investigated the contribution of frying in residential settings to ultrafine and fine particulate matter (UFP, PM2.5, respectively) exposure in homes. Production rates of 44 ± 26 particles (pt)/cm3 s (mean ± standard deviation) and 0.13 ± 0.12 μg/m3 s were found for UFP and PM2.5, respectively, from frying a variety of foods at medium heat in a loft-style apartment. Rates of 290 ± 150 pt/cm3 s and 3.5 ± 4.9 μg/m3 s were found for UFP and PM2.5, respectively, from frying with vegetable oil alone in five homes; the higher rates were ascribed to differences between the homes rather than the absence of food. The elimination of UFP and PM2.5 was found to be primarily through exhaust fans in these homes, and it was found to follow a first-order process with an elimination rate constant of 6.1 × 10−4 ± 2.5 × 10−4 s−1. The dose to an individual from frying was estimated based on the measured production and elimination rates and found to be significant when compared with the typical daily dose incurred within a home because of outside sources. Practical Implications The contribution of indoor sources to particulate matter exposure in homes remains poorly understood. Yet common household activities such as frying may produce substantial concentrations of potentially toxic particles. Because of the potential adverse health impacts associated with exposure to air pollution, potentially vulnerable individuals may be advised to remain indoors at certain times so as to reduce their overall exposure. Such interventions can be negated without proper guidance regarding the exposure involved in various indoor activities such as cooking. This paper outlines a methodology to estimate the dose to particulate matter incurred during frying and shows that this can represent a significant source of daily exposure. [ABSTRACT FROM AUTHOR]

A weekly monitoring campaign of volatile organic compounds (VOC), with single sampling of 24 h, was carried out in non-residential indoor environments such as libraries, pharmacies, offices, gymnasiums, etc., in order to evaluate the VOC concentrations to which people are exposed. Moreover, an outdoor sample was coupled to each indoor site to point out the influence of indoor sources. They were sampled with Radiello® diffusive samplers for thermal desorption and analyzed by GC-MS. As already described in other papers, the VOC levels of most of the indoor sites were higher than that observed in the corresponding outdoor sites. For example, some sites showed a level of pollution that is ten times higher than their corresponding outdoor site. The monitored environments that had higher concentrations of the investigated VOC were the pharmacies, a newspaper stand, a copy center, and the coffee shops. Analysis of the weekly average concentrations of each pollutant and the use of literature allowed pointing out some site-specific characteristics that singled out possible sources of VOC. These results were verified analyzing the indoor-outdoor ratio (I/O) too. Newspaper stands were characterized by very high concentrations of toluene and pharmacies were characterized by high concentrations of aromatic compounds. Practical Implications Indoor air pollution caused by volatile organic compounds (VOC) might affect human health at home as well as in public and commercial buildings. The main VOC sources in indoor environments are human activities, personal care products, smoking, house cleaning products, building products, and outside pollution. To preserve human health it is necessary to evaluate the average concentrations of VOC to which people are exposed and to identify the main sources of indoor pollution by means of suitable indoor monitoring campaigns in several environments. These investigations allow pointing out the characteristic critical situations of some indoor environments or some other types of environments. [ABSTRACT FROM AUTHOR]

Indoor/outdoor measurements have been performed in the Oslo metropolitan area during summer and winter periods (2002–2003) at two different residential houses. The objective of the measurement study was to characterize, physically and chemically, the particulate matter (PM) and gaseous pollutants associated with actual human exposure in the selected places, and their indoor/outdoor relationship. In this paper, we focus on the PM measurements and examine the relationship between the indoor and outdoor PM concentrations taking into account the ventilation rate, indoor sources and meteorological conditions. The indoor/outdoor measurements indicate the important contribution of the outdoor air to the indoor air quality and the influence of specific indoor sources such as smoking and cooking to the concentration of PM inside houses. However, no specific correlation was found between the indoor/outdoor concentration ratio and the meteorological parameters. Practical Implications This study provides information on the physical characteristics and the relationship of indoor to outdoor concentration of particulate matter in residential houses. Moreover, the parameters that influence this relationship are discussed. The results presented here are specific to the sampled houses and conditions used and provide data on the actual human exposure characteristics which occur in the spatial and temporal scales of the present study. [ABSTRACT FROM AUTHOR]

This study reports on a numerical investigation of transport behavior of indoor airflow and size-dependent particulate matter (PM) in multi-room buildings. An indoor size-dependent PM transport approach, combining the Eulerian large-eddy simulation of turbulent flow with the Lagrangian particle trajectory tracking, was developed to investigate indoor airflow pattern and PM1/PM2.5/PM10 removal efficiency in naturally ventilated multi-room buildings. A displacement ventilation with a measured indoor PM10 profile in Taipei Metropolis as the initial condition was carried out to characterize spatial and temporal variations of indoor PM1/PM2.5/PM10 removal behavior. The effects of indoor airflow pattern on particle transport mechanisms, e.g., deposition, suspension, migration and escape, were analyzed. Two comparison scenarios, which considered the effects of no indoor partition and different air change rate, respectively, were also conducted. In comparison with the effectiveness of PM1/PM2.5/PM10 removal, the simulated results showed that coarse particles were easier to be removed out of the building than fine particles. Natural ventilation was not an effective way to remove fine particles such as PM1 and PM2.5 in a multi-room building. Indoor partitions can impede 12% of the mean streamwise velocities and significantly increase 30–50% turbulence intensities. However, indoor partitions increased particle deposition and decreased particle escape. As a result of the two opposite particle removal mechanisms, i.e., deposition and escape, the impact of indoor partitions on PM1/PM2.5/PM10 removal behavior was not as significant as the results of airflow velocities. Practical Implications This work developed a computational fluid dynamics technique to investigate indoor airflow patterns and PM1/PM2.5/PM10 removal ability in ventilated multi-room buildings. The results of this paper can help to identify adequate PM1/PM2.5/PM10 cleaning procedure and provide useful size-dependent PM control strategy in multi-room buildings. [ABSTRACT FROM AUTHOR]

A study was carried out to investigate the feasibility of achieving ultra low respirable suspended particulates (RSP) in commercial offices without major modification of existing ventilation systems by enhancing the particulates removal efficiency of existing central ventilation systems. Four types of filters which include pre-filters, cartridge filters, bag filters and high efficiency particulates air (HEPA) filters were tested in a commercial building in Causeway Bay. The results show that an RSP objective of <20 μg/m3 could be met by removing RSP from both the return air and outdoor air supply simultaneously. This level of performance is classed as ‘excellent’ by the Hong Kong Government, Environmental Protection Department. Filters with efficiency that exceed 80% placed both in the return air and outdoor air were sufficient to meet the objective. It is not necessary to install HEPA filters to achieve the ‘excellent’ class. The outdoor air filter has great influence on the steady state indoor RSP concentration while the effective cleaning rate is governed by the return air filter. Higher efficiency filters increased the static drop but the volume flow of the air fan was not affected significantly. The additional cost incurred was <5% of the existing operation cost. Practical Implications This paper reports a field study of RSP control for an indoor office environment. The results are directly applicable to building service engineering in the design of ventilation systems using air-handling units. Field observations indicated that indoor RSP in an office environment could be suppressed below 20 μg/m3 within 1 h by the simultaneous filtration of outdoor air and return air. Outdoor air filtration has a great influence on the steady state indoor concentration and return air filtration governs the cleaning rate. It is believed that the results of this study could be extended to the cleaning of other indoor pollutants such as volatile organic compounds. [ABSTRACT FROM AUTHOR]

This paper presents the experimental and numerical modeling of contaminant dispersion in a full-scale environmental chamber with different room air distribution systems. For the experimental modeling, an area source with uniform emissions of a hypothetical contaminant (SF6) from the entire floor surface is designed and constructed. Two different types of ventilation are studied: displacement and mixing ventilation. A computer model for predicting the contaminant dispersion in indoor spaces was validated with experimental data. The validated model is used to study the effects of airflow and the area-source location on contaminant dispersion. Results show that the global airflow pattern has a strong impact on the distribution of the contaminants. In general, the personal exposure could be estimated by analyzing the relative source positions in the airflow pattern. Accordingly, the location of an exhaust diffuser may not greatly affect the airflow pattern, but can significantly affect the exposure level in the room. When designing ventilation in addition to bringing fresh air to occupants, it is important to consider the removal of contaminants released in the off-gassing of building materials. Typical indoor off-gassing examples are emissions of volatile organic compounds from building enclosure surfaces such as flooring and painted walls. In this study, we conducted experimental and numerical modeling of different area sources in a mock-up office setup, with displacement or mixing ventilation. Displacement ventilation was as successful as mixing ventilation in removing the contaminant source from the floor area. Actually, the most important consideration in the removal of these contaminants is the relative position of the area source to the main airflow pattern and the occupied zone. [ABSTRACT FROM AUTHOR]

A newly developed dustfall device that collects airborne dust by sedimentation has been evaluated in Danish schools. Dust collected over 140 days was compared with airborne dust sampled during single school days and settled floor dust sampled at the end of a school day. Measurements of culturable fungi in air samples corresponded well to those from the dustfall collector in mechanically but not naturally ventilated rooms. Levels ofβ(1→3)glucan and culturable fungi in dust from the dustfall collector and settled floor dust did not agree well. Up to 10 times moreβ(1→3)glucan per milligram dust was found in the dustfall collectors than in settled floor dust. Only in dust from the dustfall collector was the mass concentration of culturable fungi (cfu/mg) significantly correlated with the degree of dampness. The culturability of fungi in the 140-day dustfall samples tended to be lower than in other types of samples. Nonetheless, the results indicated that the dustfall collector can be used to estimate the median concentration of airborne culturable fungi, provided identical sampling periods are used for all samples. The collector is cost effective and simple to use. Traditional ways of assessing exposure to microorganisms by sampling airborne dust or dust from floors have several disadvantages. In the present paper, a new sampler, the dustfall collector, which collects airborne dust by sedimentation over a period of months, is introduced. Tests of this collector indicate that it can be used to estimate the mean concentration of airborne culturable fungi but notβ(1→3)glucan over a long period and that the method can differentiate between buildings with different levels of water damage. [ABSTRACT FROM AUTHOR]

This paper presents summary statistics of airborne culturable bacteria from the US Environmental Protection Agency Building Assessment Survey and Evaluation (BASE) study. Air samples were collected with single-stage, multiple-hole, agar impactors in 100 large office buildings in 1994–1998 to obtain normative data on indoor environmental quality. Bacterial concentrations were compared by incubation temperature, location, season, and climate zone. Forty-one percent of the samples were below the 2- or 5-min detection limits (18 or 7 CFU/m3, respectively) but less than 1% were overgrown. Mesophilic bacteria (30°C) accounted for>95% of culturable bacteria, both indoors and outdoors. Average concentrations were higher outdoors, except for Gram-positive cocci, which were the only group that were significantly higher indoors (39 vs. 24 CFU/m3), and Gram-negative cocci, for which both concentrations were low and the difference were not significant. Outdoor concentrations of culturable bacteria were somewhat higher in winter (194 vs.165 CFU/m3), and the two dominant outdoor groups were unknown bacteria and Gram-positive rods. Conversely, indoor concentrations were significantly higher in summer (116 vs. 87 CFU/m3), consisting primarily of unknown bacteria and Gram-positive cocci. Bacterial concentrations were within the ranges reported in previous studies of non-problem buildings, and the extreme aggregated indoor concentrations (e.g. the 90th percentile, 175 CFU/m3) of these 100 representative buildings may serve as upper bounds to develop interpretation guidelines for office environments and similar non-manufacturing workplaces in various climate zones. The Building Assessment Survey and Evaluation (BASE) study was one of the most comprehensive investigations of indoor environmental quality in which a standardized protocol was used to measure bioaerosols in 100 typical US office buildings. The information on the indoor and outdoor concentrations of airborne bacteria in different climate zones during the heating and cooling seasons has expanded the baseline data available for interpretation of measurements from building investigations. With suggested refinements, the BASE protocol may serve as a guide for future studies of bioaerosol concentrations, building characteristics, and occupant perceptions of the indoor environment. [ABSTRACT FROM AUTHOR]

The aim of the study reported herein was to characterize occupants’ simultaneous exposure to mixtures of organic compounds in homes. Statistical distributions for concentrations of 28 organic compounds (17 VOCs and 11 aldehydes) measured in 1417 homes were generated to analyze concentration distributions. Three candidate distributions were identified for fitting the measured data: log-normal, exponential and gamma distributions. It appears from the results of fitting tests that gamma distributions are capable of representing 28 compound concentrations. Probability distributions show that formaldehyde and acetaldehyde ranged from 25 to 220 μg/m3 at 90% probabilities and most VOCs ranged from 3 to 80 μg/m3 at 90% probabilities. In order to characterize the occupant's exposure to the mixtures, the joint probability distributions of organic compounds were generated from the best-fitted distributions of individual compounds under the assumption that concentrations of organic compounds are mutually independent in homes. These joint distributions provided the statistical data for characterizing the occupant's exposure to the mixtures of organic compounds in homes. Occupants often encounter not just one compound in indoor environments, but many compounds due to their concurrent emissions from several sources. This paper describes characteristics of statistical distributions for concentrations of 17 VOCs and 11 aldehydes in homes in Japan. After applying a probability model to the occupants’ simultaneous exposure to mixtures of organic compounds, the authors interpret the current state of the occupant's exposure to the mixtures within homes using joint probability distributions of 28 organic compounds. [ABSTRACT FROM AUTHOR]

On the international level, International Organization for Standardization (ISO), European Committee for Standardization (CEN) and American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) are writing and reviewing standards relating to the indoor environment on a regular basis. This presentation will focus on the development of standards for the indoor thermal environment and indoor air quality (ventilation). In the future, recommendations for acceptable indoor environments will be specified as classes. This allows for national differences in the requirements as well as for designing buildings for different quality levels. Several of these standards have been developed mainly by experts from Europe, North America and Japan. Are there, however, special considerations relating to South-East Asia (lifestyle, outdoor climate, economy) that are not dealt with in these standards and that will require the revision of existing standards? Critical issues are: adaptation, the effect of increased air velocity, humidity, type of indoor pollutant sources, etc. This paper will present an overview of existing methods, and discuss areas where revision of present standards or the development of new standards, are needed. The international standards for the indoor environment provide the designer with criteria, which are internationally recognized, for the design of buildings and systems. [ABSTRACT FROM AUTHOR]

Airborne particulate matter is a diverse pollutant class whose excessive presence in indoor air contributes to an array of adverse health and material-damage effects. Particles are classified according to their diameter into three size modes: ultrafine ( 0.1 μm), accumulation (0.1–2 µm), and coarse (= 2 µm). These modes have largely distinct sources and composition, and they exhibit different dynamic behaviors. The concept of mass conservation or material balance provides a foundation for quantitatively and mechanistically linking important outcome variables, such as concentrations and exposures, to the influencing input parameters. The factors governing indoor particle concentrations include direct emissions from indoor sources, ventilation supply from outdoor air, filtration, deposition onto indoor surfaces, and removal from indoor air by means of ventilation. In some circumstances, transport and transformation processes within indoor environments may also play an important role in influencing particle concentrations and consequences. Such processes include mixing, interzonal transport, resuspension, coagulation, and phase change. The paper gives a practical overview of issues related to particulate matter indoors, as well as valuable information for understanding filtration and how particles contribute to adverse health effects. [ABSTRACT FROM AUTHOR]

The mix of pollutants in indoor environments can be transformed as a consequence of chemical reactions, reducing the concentrations of the reacting species and increasing the concentrations of the products. Within this broad topic, the current paper focuses on significant research that has recently occurred in three subtopics: (1) Studies that have experimentally demonstrated the importance of hydroxyl radicals in indoor transformations. In the cases discussed, OH is a product of ozone/terpene reactions and goes on to react with other products, as well as the original terpene. The results demonstrate that the hydroxyl radical is responsible for a large fraction of the oxidized products, including certain products that cannot be made by ozone pathways alone. (2) Chemistry that occurs on indoor surfaces. Given the large surface-to-volume ratios indoors, such reactions may have a larger impact on indoor air quality than those that occur in the gas phase. In at least one case, ozone interacting with carpets, this has been demonstrated to be the case. (3) The impact that the products of indoor chemistry can have on building occupants. A major limitation in evaluating the impacts of indoor chemistry has been the inability to measure many of the reaction products. Sensory measurements are useful in detecting changes derived from indoor chemistry—changes missed by the analytical methods routinely used to evaluate indoor air. Sensitive physiological indicators of effects, such as eye blink rate, are also being investigated. Reactions among indoor pollutants are the principal source of short-lived, highly reactive compounds in the setting where humans spend the majority of their time—indoors. Indoor chemistry impacts indoor air quality. A better understanding of hydroxyl radical chemistry allows us to predict some of the compounds that humans are exposed to under certain situations, even if such species cannot be readily measured. Emissions from materials can be significantly altered by surface chemistry, and the products of such reactions often dominate a material's long-term emissions. Surface chemistry may help us better understand the reasons for complaints in “problem” buildings, especially damp buildings. A better understanding of the impact of indoor chemical reactions on human comfort and health would help prioritize efforts to improve indoor air quality. [ABSTRACT FROM AUTHOR]

Scale modeling is a useful tool for analyzing complex indoor spaces. Scale model experiments can reduce experimental costs, improve control of flow and temperature conditions, and provide a practical method for pretesting full-scale system modifications. However, changes in physical scale and working fluid (air or water) can complicate interpretation of the equivalent effects in the full-scale structure. This paper presents a detailed scaling analysis of a water tank experiment designed to model a large indoor space, and experimental results obtained with this model to assess the influence of furniture and people in the pollutant concentration field at breathing height. Theoretical calculations are derived for predicting the effects from losses of molecular diffusion, small scale eddies, turbulent kinetic energy, and turbulent mass diffusivity in a scale model, even without Reynolds number matching. Pollutant dispersion experiments were performed in a water-filled 30:1 scale model of a large room, using uranine dye injected continuously from a small point source. Pollutant concentrations were measured in a plane, using laser-induced fluorescence techniques, for three interior configurations: unobstructed, table-like obstructions, and table-like and figure-like obstructions. Concentrations within the measurement plane varied by more than an order of magnitude, even after the concentration field was fully developed. Objects in the model interior had a significant effect on both the concentration field and fluctuation intensity in the measurement plane. This scale model study demonstrates both the utility of scale models for investigating dispersion in indoor environments and the significant impact of turbulence created by furnishings and people on pollutant transport from floor level sources. In a room with no furniture or occupants, the average concentration can vary by about a factor of 3 across the room. Adding furniture and occupants can increase this spatial variation by another factor of 3. [ABSTRACT FROM AUTHOR]

Abstract We describe a framework for developing response recommendations to unexpected toxic pollutant releases in commercial buildings. It may be applied in conditions where limited building- and event-specific information is available. The framework is based on a screening-level methodology to develop insights, or rules-of-thumb, into the behavior of airflow and pollutant transport. A three-stage framework is presented: (1) develop a building taxonomy to identify generic, or prototypical, building configurations; (2) characterize uncertainty and conduct simulation modeling to predict typical airflow and pollutant transport behavior; and (3) rank uncertainty contributions to determine how information obtained at a site might reduce uncertainties in the model predictions. The approach is applied to study a hypothetical pollutant release on the first floor of a five-story office building. Key features that affect pollutant transport are identified and described by value ranges in the building stock. Simulation modeling provides predictions and uncertainty estimates of time-dependent pollutant concentrations, following a release, for a range of indoor and outdoor conditions. In this exercise, we predict concentrations on the fifth floor to be an order of magnitude less than on the first, coefficients of variation greater than 2, and information about the HVAC operation and window position most reducing uncertainty in predicted peak concentrations. Practical Implications In the event of a toxic pollutant release in or near a building, first-responders are faced with making rapid response decisions with little – and often highly uncertain – information. This paper presents an analytical framework for developing such rapid response decisions and statistical tools for describing and ranking the associated uncertainties. An algorithmic decision tree, based on this analysis framework, can be developed in the future for identifying the best possible rapid-response decisions in the field, based on available information. Such software can be placed, for example, on a personal digital assistant of first-responders. [ABSTRACT FROM AUTHOR]

Abstract As ventilation efficiency in a room is not always uniformly distributed, an index for measuring ventilation efficiency at a concerned point or in a concerned local domain is required. Local ventilation efficiency is often represented by the rate of the averaged concentration of the local domain to that of exhausted air from the room. From the age theory of air, it is well known that the averaged concentration in a room corresponds to the mean staying time of contaminant. Evaluating the domain-averaged concentration (C domain ) means evaluating the average staying time of the contaminant in the domain. It can be only one part of the whole room and can be considered as an occupied zone. Visitation frequency (VF) and the average staying time of the contaminant for one visitation in the local domain (T p ) are introduced to analyze the average staying time of the contaminant in the local domain. The value of VF is strongly affected by the position of the local domain in the room; that is, the position of the local domain in the whole flow field of the room. T p represents the property of the flow pattern in the local domain. As the indication of VF and T p represent the mechanism for forming the domain-averaged concentration, they are deeply related to local purging flow rate, which represents the airflow rate for defining the domain-averaged concentration. As VF and T p are related to the contaminant transportation property, it is effective to analyze them by particle tracking method. A CFD method of large eddy simulation (LES) was thereby carried out in this study. The prediction result by LES is also validated by a precise model experiment. In this paper, the detailed analysis of VF and T p is carried out on the basis of the particle tracking method utilizing the LES result in order to clarify the mechanism of the domain-averaged concentration. The analyzed room has one supply inlet and one exhaust outlet. A clear re-circulating flow, generated by the forced ventilation, is observed in the room. The value of VF is examined with three types of local domains in the room model. In the room model, VF shows a value of 5.70 when the local domain occupies half of the room. It becomes smaller when the size of the local domain is reduced. Practical Implications In recent years, numerical simulation of airflow, temperature, and contaminant distribution field is used in the design of room air-conditioning or of indoor air quality. It is effective in analyzing the structure of the contaminant distribution field and can be used to design a precise controlling method. The averaged concentration in the local domain is the important controlling parameter in the local ventilation design. To analyze and evaluate the domain-averaged concentration, the contaminant distribution field is analyzed and assessed in this study with new concepts, which are visitation frequency and the average particle staying time in the domain, derived from the numerical simulation technique. [ABSTRACT FROM AUTHOR]

This paper presents pollutant concentrations and performance data for code-required mechanical ventilation equipment in 23 low-income apartments at 4 properties constructed or renovated 2013-2017. All apartments had natural gas cooking burners. Occupants pledged to not use windows for ventilation during the study but several did. Measured airflows of range hoods and bathroom exhaust fans were lower than product specifications. Only eight apartments operationally met all ventilation code requirements. Pollutants measured over one week in each apartment included time-resolved fine particulate matter (PM2.5 ), nitrogen dioxide (NO2 ), formaldehyde and carbon dioxide (CO2 ) and time-integrated formaldehyde, NO2 and nitrogen oxides (NOX ). Compared to a recent study of California houses with code-compliant ventilation, apartments were smaller, had fewer occupants, higher densities, and higher mechanical ventilation rates. Mean PM2.5 , formaldehyde, NO2 , and CO2 were 7.7 µg/m3 , 14.1, 18.8, and 741 ppm in apartments; these are 4% lower, 25% lower, 165% higher, and 18% higher compared to houses with similar cooking frequency. Four apartments had weekly PM2.5 above the California annual outdoor standard of 12 µg/m3 and also discrete days above the World Health Organization 24-hour guideline of 25 µg/m3 . Two apartments had weekly NO2 above the California annual outdoor standard of 30 ppb.

This paper describes file 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 SF[sub6] 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 SF[sub6] 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. [ABSTRACT FROM AUTHOR]

Sensory responses to clean air and air polluted by five building materials under different combinations of temperature and humidity in the ranges 18-28°C and 30-70%RH were studied in the laboratory, A specially designed test system was built and a set of experiments was designed to observe separately the impact of temperature and humidity on the perception of air quality/odour intensity, and on the emission of pollutants from the materials. This paper reports on the impact on perception, The odour intensity of air did not change significantly with temperature and humidity; however; a strong and significant impact of temperature and humidity on the perception of air quality was bund. The air was perceived ac less acceptable with increasing temperature and humidity. This impact decreased with an increasing level of air pollution. Significant linear correlations were found between acceptability and enthalpy of the air at all pollution levels tested, and a linear model was established to describe the dependence of perceived air quality on temperature and humidity at different pollution levels, [ABSTRACT FROM AUTHOR]

The author explores on the dominance of Nordic researchers in the journal "Indoor Air." Four out of 10 "Indoor Air" conferences and two out nine Healthy Building conferences have been or will be held in Nordic countries. He believes that the number of delegates at these conferences are also dominated by those coming from small Nordic countries. A list of the most highly cited papers published in the last 5 years which further shows Nordic dominance within the journal is also presented.

Presents an overview of the articles featured in the March 1999 issue of the 'Indoor Air' journal. Cost issues of field studies of indoor environmental conditions; Aspects of ventilation performance in buildings; Concern about increasing reports of mold and mildew in residences in Japan.