Ventilation and health in non-industrial indoor environments: report from a European multidisciplinary scientific consensus meeting (EUROVEN)

Numerical study of different ventilation schemes in a classroom for efficient aerosol control

The air quality is a parameter to be controlled in order to live in a comfortable place. This paper analyzes the trajectory of aerosols exhaled into the environment in a classroom. Three scenarios are investigated; without ventilation, with natural and with mechanical ventilation. A multi-phase computational fluid study based on Eulerian-Lagrangian techniques is defined. Temperature and ambient relative humidity, as well as air velocity, direction and pressure is taken into account. For droplets evaporation, mass transfer and turbulent dispersion have been added. This work tends to be of great help in various areas, such as the field of medicine and energy engineering, aiming to show the path of aerosols dispersed in the air. The results show that the classroom with a mechanical ventilation scheme offers good results when it comes to an efficient control of aerosols. In all three cases, aerosols exhaled into the environment impregnate the front row student in the first 0.5 s. Reaching the time of 4, 2 and 1 s, in the class without ventilation, mechanical and natural ventilation, respectively, the aerosols have been already deposited on the table of the person in the first row, being exposed for longer in the case of no ventilation. Particles with a diameter of less than 20 μm are distributed throughout the classroom over a long period. The air jet injected into the interior space offers a practically constant relative humidity and a drop in temperature, slowing down the process of evaporation of the particles. In the first second, it can be seen that a mass of 0.0025 mg formed by 9 million droplets accumulates, in cases without ventilation and natural ventilation. The room with a mechanical installation accumulated 5.5 million particles of mass 0.0028 mg in the first second. The energy losses generated by natural ventilation are high compared to the other scenarios, exactly forty and twenty times more in the scenario with mechanical ventilation and without ventilation, respectively.

A single-blind field intervention study of whether increased bedroom ventilation improves sleep quality

A four-week-long field intervention experiment was conducted in twenty-nine bedrooms with extract ventilation systems and air inlet vents. During the first week no interventions took place. In the three weeks that followed, each participant slept for one week under a low, medium, and high ventilation rate condition in a balanced order. These conditions were established by covertly altering the fan speed of the exhaust ventilation system without changing other settings. Participants were not informed when or even whether the changes to bedroom ventilation would be executed. The bedroom environmental quality was monitored continuously and sleep quality was monitored using wrist-worn trackers. Tests of cognitive performance were conducted in the evening and morning. In twelve bedrooms where clear differences between the three ventilation conditions occurred, as indicated by the measured CO₂ concentrations, participants had significantly less deep sleep, more light sleep and more awakenings at lower ventilation rate conditions. In twenty-three bedrooms where a clear difference in ventilation rate between the high and low ventilation conditions was observed, as confirmed by the measured CO₂ concentrations, the duration of deep sleep was significantly shorter in the low ventilation rate condition. No differences in cognitive performance between conditions were observed. At lower ventilation rate conditions, the concentrations of CO₂ increased, as did the relative humidity, while bedroom temperatures remained unchanged. The present results, which were obtained in actual bedrooms, confirm the findings in previous studies of a positive effect of increased ventilation on sleep quality. Further studies with larger populations and better control of bedroom conditions, particularly ventilation, are required.

Prevalence and risk factors of chronic respiratory symptoms in public and private school teachers in north-western Ethiopia: results from a multicentre cross-sectional study

OBJECTIVE

This study aimed to investigate the prevalence and risk factors of chronic respiratory symptoms among school teachers in Gondar city, north-western Ethiopia.

DESIGN

A school-based cross-sectional study was conducted from April to May 2019. A self-administered British Medical Research Council Questionnaire was used to assess chronic respiratory symptoms. Data were entered into Epi Info V.7 and Stata V.14 was used for analysis. A multivariable logistic regression analysis was conducted to identify factors associated with chronic respiratory symptoms. The association was determined using adjusted OR (AOR) with a 95% CI at a value of p<0.05.

SETTING

The study was conducted in public and private schools in Gondar city.

PARTICIPANTS

A total of 822 teachers participated in this study.

OUTCOME MEASURES

The primary outcome is the prevalence of chronic respiratory symptoms.

RESULTS

The total response rate was 97.4%. The majority, 532 (64.7%) of the participants, were male. The mean age (±SD) of the respondents was 36.69 (±6.93) years. The total prevalence of chronic respiratory symptoms in the previous 12 months among teachers in Gondar city was found to be 31.14% (95% CI 27.99% to 34.43%). A family history of respiratory problems (AOR=1.90; 95% CI 1.07 to 3.37), an overweight body mass index (AOR=2.57; 95% CI 1.57 to 4.21), exposure to secondhand cigarette smoke at home (AOR=9.85; 95% CI 4.77 to 20.33), use of chalk (AOR=1.97; 95% CI 1.25 to 3.09), and failure to open windows during class (AOR=2.15; 95% CI 1.02 to 4.52) were risk factors for chronic respiratory symptoms.

CONCLUSION

This study concluded that the prevalence of chronic respiratory symptoms was high among teachers. Making a smoking-free zone, avoiding smoking in public places, improving the ventilation conditions of the classrooms and controlling the chalk dust are all necessary actions to take to reduce chronic respiratory symptoms.

Hazard Evaluation of Indoor Air Quality in Bank Offices

IAQ is a crucial factor affecting the health, comfort, and productivity of workers, particularly those working in enclosed spaces like bank offices. This study aimed to evaluate the IAQ of a bank office’s operational area and vault by analyzing concentrations of CO2, TVOC, PM10, and PM2.5, as well as temperature, relative humidity, and air movement. Two different ventilation systems were compared to assess their impact on IAQ. The acquired data were statistically analyzed using mean comparison t-tests and hazard ratio analysis. The results revealed that indoor concentrations of PM2.5 and CO2 significantly contribute to the total hazard ratio, indicating the need to reduce their levels below reference values. The study also found that the ventilation system significantly affects indoor air quality, and concentrations of TVOC, CO2, PM10, and PM2.5 in the air are considerable. Significantly, the study found that bank offices with split unit air-conditioners had the highest mean CO2 levels, indicating poor ventilation. Overall, the study reveals that the building, activities, and ventilation in bank offices have a profound influence on IAQ parameters, primarily PM2.5 and CO2. Further research is required to formulate strategies for enhancing IAQ in these settings.

Quantification of how mechanical ventilation influences the airborne infection risk of COVID-19 and HVAC energy consumption in office buildings

This paper presents an EnergyPlus-based parametric analysis to investigate the infection risk of Coronavirus Disease 2019 (COVID-19) under different mechanical ventilation scenarios for a typical medium-sized office building in various climate zones. A Wells-Riley (WR) based Gammaitoni-Nucci (GN) model was employed to quantitatively calculate the airborne infection risk. The selected parameters for the parametric analysis include the climate zone, outdoor air fraction, fraction of infectors, quanta generation rate, and exposure time. The loss and deposition of particles are not considered. The results suggest that the COVID-19 infection risk varies significantly with climate and season under different outdoor air fraction scenarios since the building heating and cooling load fundamentally impacts the supply airflow rate and thus directly influences the amount of mechanical ventilation, which determines the dilution ratio of contaminants. This risk assessment identified the climate zones that benefit the most and the least from increasing the outdoor air fraction. The climate zones such as 1A (Honolulu, HI), 2B (Tucson, AZ), 3A (Atlanta, GA), and 7 (International Falls, MN) are the most energy-efficient locations when it comes to increasing the outdoor air fraction to reduce the COVID-19 infection risk. In contrast, the climate zones such as 6A (Rochester, MN) and 6B (Great Falls, MT) are the least energy-efficient ones. This paper facilitates understanding a widely recommended COVID-19 risk mitigation strategy (i.e., increase the outdoor airflow rate) from the perspective of energy consumption.

Electronic Supplementary Material

Supplementary material is available for this article at 10.1007/s12273-022-0937-5 and is accessible for authorized users.

Associative evidence for the potential of humidification as a non-pharmaceutical intervention for influenza and SARS-CoV-2 transmission

BACKGROUND

Both influenza and SARS-CoV-2 viruses show a strong seasonal spreading in temperate regions. Several studies indicated that changes in indoor humidity could be one of the key factors explaining this.

OBJECTIVE

The purpose of this study is to quantify the association between relevant epidemiological metrics and humidity in both influenza and SARS-CoV-2 epidemic periods.

METHODS

The atmospheric dew point temperature serves as a proxy for indoor relative humidity. This study considered the weekly mortality rate in the Netherlands between 1995 and 2019 to determine the correlation between the dew point and the spread of influenza. During influenza epidemic periods in the Netherlands, governmental restrictions were absent; therefore, there is no need to control this confounder. During the SARS-CoV-2 pandemic, governmental restrictions strongly varied over time. To control this effect, periods with a relatively constant governmental intervention level were selected to analyze the reproduction rate. We also examine SARS-CoV-2 deaths in the nursing home setting, where health policy and social factors were less variable. Viral transmissibility was measured by computing the ratio between the estimated daily number of infectious persons in the Netherlands and the lagged mortality figures in the nursing homes.

RESULTS

For both influenza and SARS-CoV-2, a significant correlation was found between the dew point temperature and the aforementioned epidemiological metrics. The findings are consistent with the anticipated mechanisms related to droplet evaporation, stability of virus in the indoor environment, and impairment of the natural defenses of the respiratory tract in dry air.

SIGNIFICANCE

This information is helpful to understand the seasonal pattern of respiratory viruses and motivate further study to what extent it is possible to alter the seasonal pattern by actively intervening in the adverse role of low humidity during fall and winter in temperate regions.

IMPACT

A solid understanding and quantification of the role of humidity on the transmission of respiratory viruses is imperative for epidemiological modeling and the installation of non-pharmaceutical interventions. The results of this study indicate that improving the indoor humidity by humidifiers could be a promising technology for reducing the spread of both influenza and SARS-CoV-2 during winter and fall in the temperate zone. The identification of this potential should be seen as a strong motivation to invest in further prospective testing of this non-pharmaceutical intervention.

Development and application of an indoor carbon dioxide metric

Indoor carbon dioxide (CO₂ ) concentrations have been considered for decades in evaluating indoor air quality (IAQ) and ventilation, and more recently in discussions of the risk of airborne infectious disease transmission. However, many of these applications reflect a lack of understanding of the connection between indoor CO₂ levels, ventilation, and IAQ. For example, a single indoor concentration such as 1000 ppm_v is often used as a metric of IAQ and ventilation without an understanding of the significance of this or any other value. CO₂ concentrations are of limited value as IAQ metrics, and a single concentration will not serve as a ventilation indicator for spaces with different occupancies and ventilation requirements. An approach has been developed to estimate a space-specific CO₂ level that can serve as a metric of outdoor ventilation rates. The concept is to estimate the CO₂ concentration that would be expected in a specific space given its intended or expected ventilation rate, the number of occupants, the rate at which they generate CO₂ , and the time that has transpired since the space was occupied. This paper describes the approach and presents example calculations for several commercial, institutional, and residential occupancies.

Building and Health: Mapping the Knowledge Development of Sick Building Syndrome

At present, with more and more attention paid to the impact of buildings on the health and well-being of occupants, sick building syndrome (SBS) has become a global concern. Since the introduction of SBS by the World Health Organization (WHO) in 1983, thousands of research literatures have been published in this field. This paper systematically arranges knowledge development of SBS through bibliometric analysis, exploring the most influential countries, institutions, journals and scholars, as well as the main subject categories and keywords. Main path analysis (MPA) was used to list development trajectory under inheritance relationship of SBS knowledge, including symptom analysis, risk factors of SBS and the improved impact of ventilation on SBS and productivity. Furthermore, it is an emerging research trend to propose SBS solution in the building design stage.

Indoor air quality and sick building syndrome in a university setting: a case study in Greece

The perceived Indoor Air Quality (IAQ), the prevalence of Sick Building Syndrome (SBS) symptoms and its contributing risk factors were assessed in a university during the period of the economic crisis in Greece. Data was collected from 613 employees via questionnaires. Hierarchical linear regression analysis was performed. The most prevalent perceived IAQ complaints were 'Dust and dirt' (63.2%), 'Room temperature too low' (24.9%) and 'Varying room temperature' (24.4%). The most frequently reported SBS symptom was 'Fatigue' (34.1%). The prevalence of General, Mucosal and Dermal symptoms was 40.8%, 19.8% and 8.1%, respectively. Several contributing risk factors were identified, such as IAQ Discomfort Scale, atopy, sleep problems, female, exposure to biological and chemical agents, PC-use, Psychosocial Work Scale and job satisfaction. Poor perceived IAQ and high prevalence of SBS symptoms were reported from the university staff in a temperate climate country. SBS seemed to be multifactorial.

Modelling botanical biofiltration of indoor air streams contaminated by volatile organic compounds

Botanical filtration is a biological-based treatment method suitable for removing hazardous volatile organic compounds (VOCs) from air streams, based on forcing an air flow through a porous substrate and foliage of a living botanical compartment. The pathways and removal mechanisms during VOC bioremediation have been largely investigated; however, their mathematical representation is well established only for the non-botanical components of the system. In this study, we evaluated the applicability of such a modelling scheme to systems which include a botanical compartment. We implemented a one-dimensional numerical model and performed a global sensitivity analysis to measure the input parameters influence on the transient and steady biofilter responses. We found that the most sensitive parameters on the transient-state behaviour were the mass transfer coefficient between gas and solid surfaces, and the fraction of solid surfaces covered by the biofilm; the steady-state response was primarily influenced by the biofilm specific surface area and the fraction of surfaces covered by the biofilm. We calibrated the identified set of parameters and successfully validated the model against data from a pilot-scale installation. The results showed that the application of the model to systems with a botanical compartment is feasible, although under a strict set of assumptions.

Indoor air quality assessment in dwellings with different ventilation strategies in Nunavik and impacts on bacterial and fungal microbiota

Indoor air quality is a major issue for public health, particularly in northern communities. In this extreme environment, adequate ventilation is crucial to provide a healthier indoor environment, especially in airtight dwellings. The main objective of the study is to assess the impact of ventilation systems and their optimization on microbial communities in bioaerosols and dust in 54 dwellings in Nunavik. Dwellings with three ventilation strategies (without mechanical ventilators, with heat recovery ventilators, and with energy recovery ventilators) were investigated before and after optimization of the ventilation systems. Indoor environmental conditions (temperature, relative humidity) and microbiological parameters (total bacteria, Aspergillus/Penicillium, endotoxin, and microbial biodiversity) were measured. Dust samples were collected in closed face cassettes with a polycarbonate filter using a micro-vacuum while a volume of 20 m³ of bioaerosols were collected on filters using a SASS3100 (airflow of 300 L/min). In bioaerosols, the median number of copies was 4.01 × 10³ copies/m³ of air for total bacteria and 1.45 × 10¹ copies/m³ for Aspergillus/Penicillium. Median concentrations were 5.13 × 10⁴ copies/mg of dust, 5.07 × 10¹ copies/mg, 9.98 EU/mg for total bacteria, Aspergillus/Penicillium and endotoxin concentrations, respectively. The main microorganisms were associated with human occupancy such as skin-related bacteria or yeasts, regardless of the type of ventilation.

Indoor Air Quality Strategies for Air-Conditioning and Ventilation Systems with the Spread of the Global Coronavirus (COVID-19) Epidemic: Improvements and Recommendations

The coronavirus has come to the world and spread with great wide among the countries of the world and has resulted in numerous infections that exceeded 167,181,023 million patients and are close to 3.5 deaths by September 2021. It also brought with it panic and fear, halted many activities, and led to the decline of the global economy. It changed human behavior and forced people to change their lifestyles to avoid infection. One of the most sectors that must be taken into consideration through pandemic coronavirus (COVID-19) around the globe is the air conditioning systems. The HVAC systems depend on the air as a heat transfer medium. The air contains a group of pollutants, viruses, and bacteria, and it affects and destroys human life. The air filter plays a major role as an important component in the air conditioning systems. Thus, it requires more effort by researchers to improve its design to prevent the ultra-size of particles loaded with coronavirus (COVID-19). This paper provides insight into the design of existing combined air-conditioners on their suitability and their impact on the spread of the hybrid coronavirus epidemic and review efforts to obtain a highly efficient air filter to get rid of super-sized particles for protection against epidemic infection. In addition, important guideline recommendations have been made to limit the spread of the COVID-19 virus and to obtain indoor air quality in air-conditioned places.

Dust and microbial filtration performance of regular and antimicrobial HVAC filters in realistic conditions

Two polypropylene HVAC electret filters: a regular filter and an antimicrobial filter containing zinc pyrithione (ZPT), were compared for filtration performance. The study was conducted over 7 months in realistic conditions with semi-urban outdoor air. Several parameters were monitored over the study period: the average temperature was about 20 °C and relative humidity about 60%, the average inlet concentration of cultivable microorganisms was 50 CFU m^-3, the average inlet concentration of particles was 10 μg m^-3, the filter pressure drop increased moderately by about 30 Pa, and the particle collection efficiency of soda fluorescein (median diameter 0.35 μm) decreased in the first half of the study period by about 30% and then stabilized. The microbial concentration on the filters was quantified every 2 months using an innovative methodology based on media coupons in conjunction with microorganism quantification by CFU counting, with 5 culture media favorable to bacteria and/or fungi growth. The microbial concentrations on the filters were between 100 and 2000 CFU cm^-2. The antimicrobial effect of zinc pyrithione was confirmed by the fungi cultivated with DRBC agar: no effects in the level of filter clogging were revealed in the range studied. The high statistical deviation in the results regarding the inhibiting effect of zinc pyrithione on bacteria prevents any conclusion.

The Role of HVAC Design and Windows on the Indoor Airflow Pattern and ACH

The purpose of heating, ventilation, and air conditioning (HVAC) systems are to create optimum thermal comfort and appropriate indoor air quality (IAQ) for occupants. Air ventilation systems can significantly affect the health risk in indoor environments, especially those by contaminated aerosols. Therefore, the main goal of the study is to analyze the indoor airflow patterns in the heating, ventilation, and air conditioning (HVAC) systems and the impact of outlets/windows. The other goal of this study is to simulate the trajectory of the aerosols from a human sneeze, investigate the impact of opening windows on the number of air changes per hour (ACH) and exhibit the role of dead zones with poor ventilation. The final goal is to show the application of computational fluid dynamics (CFD) simulation in improving the HVAC design, such as outlet locations or airflow rate, in addition to the placement of occupants. In this regard, an extensive literature review has been combined with the CFD method to analyze the indoor airflow patterns, ACH, and the role of windows. The airflow pattern analysis shows the critical impact of inflow/outflow and windows. The results show that the CFD model simulation could exhibit optimal placement and safer locations for the occupants to decrease the health risk. The results of the discrete phase simulation determined that the actual ACH could be different from the theoretical ACH as the short circuit and dead zones affect the ACH.

Spread of respiratory infections in student dormitories in China

OBJECTIVES

Student dormitory rooms in China are characterized by small space and high occupancy. This study aims to investigate infection rates for common colds and influenza among college students in a Chinese university and their association with the dormitory environment.

METHODS

This study involved two phases. In Phase I, 2978 students living in 998 dorm rooms in 12 buildings responded to a questionnaire survey on infections in four seasons. In Phase II, based on the data obtained from the questionnaire survey, we selected 242 dorm rooms to measure air temperature, relative humidity and CO₂ concentration in both summer and winter. Ventilation rates at night were calculated based on measured CO₂ concentrations.

RESULTS

We found that students had infections more often in winter, and in rooms with higher occupancy and dampness problems. The median value of the ventilation rate in dorm rooms in summer was 10.7 L/s per person, while it was 4.10 L/s per person in winter. There were significant associations between ventilation rate per person at night and common cold and influenza both in summer and winter (p < 0.05). A combination of dampness and low ventilation rate significantly increased the risk of common colds (adjusted odds ratios, AOR: 1.26-1.91) and influenza (AOR: 1.49-2.20).

CONCLUSION

College students living in a crowded dormitory room with low ventilation and dampness problems had more common colds and influenza infections.

Indoor air quality investigation of a badminton hall in humid season through objective and subjective approaches

This study investigated the indoor air quality (IAQ) during humid season in an old badminton hall, to explore the IAQ characteristics of natural ventilated sports buildings for public use. The indoor air parameters (temperature, relative humidity and air velocity) and indoor air pollutants (CO₂, TVOC, PM_2.5 and PM₁₀) were measured. A subjective approach was carried out through questionnaire survey. 185 valid questionnaires were recovered, and 68.7% of the participants had exercised. Results show that the indoor air qualities obtained through objective and subjective approaches were obviously different. Indoor PM, TVOC and CO₂ concentrations were normal, but 37.3% of the participants complained about the building materials' smell and 73.5% of the participants reported obvious sweaty odor. Physical activity might reduce a person's sensitivity to the environment. The participants generally felt warm and hot because of the high relative humidity. Post-exercise participants felt significantly hotter than those who did not exercise, and were generally more receptive to IAQ. The method of Fanger was employed to narrow the gap between subjective and objective approaches with a modified parameter, and to furtherly estimate the ventilation. The present study demonstrates the necessity to combine two approaches together to assess the IAQ in sports buildings.

Performance characteristics of a fan filter unit (FFU) in mitigating particulate matter levels in a naturally ventilated classroom during haze conditions

The performance of a low-cost fan filter unit (FFU) in mitigating hazardous particulate matter (PM) levels in a naturally ventilated school classroom is presented. The FFU can be considered as a simplified mechanical ventilation and air-conditioning system without heating and cooling functions. The FFU improves indoor air quality through introduction of cleaned outdoor air to flush out internally generated heat and moisture and reducing infiltration by maintaining indoor pressurization. Indoor particle number concentrations were reduced between 85% and 95%. The particle removal performance (PRF_FFU ) of the FFU is determined and incorporated into the augmented façade penetration factor (P_aug ). A case-specific recursive dynamic mass balance model is used to characterize the infiltration factor (F_INF ), deposition rate (K), and the penetration efficiency (P_aug ) from continuously monitored indoor and outdoor mass concentration levels. Computed "P_aug " (0.07, 0.09, and 0.13) and "F_INF " (0.06, 0.08, and 0.11), respectively, for PM10, PM2.5, and PM1 suggest that exposure to PM was significantly reduced indoors. The effectiveness of the FFU for reduced "F_INF " and "P_aug " may be attributed to its superior filtration, dilution, and exfiltration mechanisms. In comparison with alternative PM mitigation solutions, the FFU is effective, affordable, and sustainable.

Effects of Night Ventilation on Indoor Air Quality in Educational Buildings—A Field Study

Night ventilation methods have been used in educational buildings to guarantee indoor air quality at the beginning of occupied periods. A typical method has been to pre-start ventilation 2 h before the space usage. Another selection has been to ventilate a building continuously during the night with a minimum airflow rate that can dilute material emissions. In this study, the pre-started, continuous, and intermittent ventilation methods were compared by assessing indoor air quality in field measurements. The daytime ventilation was operating normally. The test periods lasted for 2 weeks. Indoor air quality was assessed by measuring the total volatile organic compounds and microbial concentrations using the quantitative polymerase chain reaction method. Additionally, the thermal conditions, carbon dioxide, and pressure differences over the building envelope were measured. The results show that the night ventilation strategy had negligible effects on microbial concentrations. In most cases, the indoor air microbial concentrations were only a few percent of those found outdoors. The averaged concentration of total volatile organic compounds was at the same level with all the night ventilation methods at the beginning of the occupied periods in the mornings. The concentrations reached a minimum level after 2-h ventilation. The concentrations of total volatile organic compounds were higher during the day than at night. This reveals that space usage had the largest effect on the total volatile organic compounds. Generally, the results show that continuous night ventilation does not significantly affect the biological and chemical contaminants. Consequently, a 2-h flushing period is long enough to freshen indoor air before occupancy.

Quantification of Air Change Rate by Selected Methods in a Typical Apartment Building

An important parameter that affects indoor climate of buildings and also ventilation heat losses and gains is the speed of air change between the outdoor environment and the interior of buildings. Indoor air quality is therefore significantly associated with ventilation. Quantification of air change rate is complicated, because it is impacted by many parameters, the most variable of which is air flow. This study focuses on the determination and comparison of air change rate values in two methods by quantification of the aerodynamic coefficient Cp = Cpe − Cpi, so-called “aerodynamic quantification of the building” and the methodology based on “experimental measurements of carbon dioxide”. The study describes and takes into account the effect of wind, building parameters and air permeability for the building using “aerodynamic quantification of the building”. The paper compares these calculated results with the values obtained from experimental measurements method of carbon dioxide in a selected reference room in apartment building and evaluates the accuracy of the prediction of the air exchange rate obtained by these methods. At higher wind speeds the values of air change rate with considering the effect of openings are closer to the values obtained based on experimental measurements of carbon dioxide and the difference between the values without considering the effect of openings increases significantly.

Residential air-change rates: A critical review

Air-change rate is an important parameter influencing residential air quality. This article critically assesses the state of knowledge regarding residential air-change rates, emphasizing periods of normal occupancy. Cumulatively, about 40 prior studies have measured air-change rates in approximately 10,000 homes using tracer gases, including metabolic CO₂ . The central tendency of the air-change rates determined in these studies is reasonably described as lognormal with a geometric mean of 0.5 h^-1 and a geometric standard deviation of 2.0. However, the geometric means of individual studies vary, mainly within the range 0.2-1 h^-1 . Air-change rates also vary with time in residences. Factors influencing the air-change rate include weather (indoor-outdoor temperature difference and wind speed), the leakiness of the building envelope, and, when present, operation of mechanical ventilation systems. Occupancy-associated factors are also important, including window opening, induced exhaust from flued combustion, and use of heating and cooling systems. Empirical and methodological challenges remain to be effectively addressed. These include clarifying the time variation of air-change rates in residences during occupancy and understanding the influence of time-varying air-change rates on tracer-gas measurement techniques. Important opportunities are available to improve understanding of air-change rates and interzonal flows as factors affecting the source-to-exposure relationships for indoor air pollutants.

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

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

Classrooms' indoor environmental conditions affecting the academic achievement of students and teachers in higher education: A systematic literature review

This study reports the outcomes of a systematic literature review, which aims to determine the influence of four indoor environmental parameters - indoor air, thermal, acoustic, and lighting conditions -on the quality of teaching and learning and on students' academic achievement in schools for higher education, defined as education at a college or university. By applying the Cochrane Collaboration Method, relevant scientific evidence was identified by systematically searching in multiple databases. After the screening process, 21 publications of high relevance and quality were included. The collected evidence showed that the indoor environmental quality (IEQ) can contribute positively to the quality of learning and short-term academic performance of students. However, the influence of all parameters on the quality of teaching and the long-term academic performance could not be determined yet. Students perform at their best in different IEQ conditions, and these conditions are task-dependent, suggesting that classrooms which provide multiple IEQ classroom conditions facilitate different learning tasks optimally. In addition, the presented evidence illuminates how to examine the influence of the IEQ on users. Finally, this information supports decision-makers in facility management and building systems engineering to improve the IEQ, and by doing so, allow teachers and students to perform optimally.

Health, work performance, and risk of infection in office-like environments: The role of indoor temperature, air humidity, and ventilation

Epidemiological and experimental studies have revealed the effects of the room temperature, indoor air humidity, and ventilation on human health, work and cognitive performance, and risk of infection. In this overview, we integrate the influence of these important microclimatic parameters and assess their influence in offices based on literature searches. The dose-effect curves of the temperature describe a concave shape. Low temperature increases the risk of cardiovascular and respiratory diseases and elevated temperature increases the risk of acute non-specific symptoms, e.g., dry eyes, and respiratory symptoms. Cognitive and work performance is optimal between 22 °C and 24 °C for regions with temperate or cold climate, but both higher and lower temperatures may deteriorate the performances and learning efficiency. Low temperature may favor virus viability, however, depending on the status of the physiological tissue in the airways. Low indoor air humidity causes vulnerable eyes and airways from desiccation and less efficient mucociliary clearance. This causes elevation of the most common mucous membrane-related symptoms, like dry and tired eyes, which deteriorates the work performance. Epidemiological, experimental, and clinical studies support that intervention of dry indoor air conditions by humidification alleviates symptoms of dry eyes and airways, fatigue symptoms, less complaints about perceived dry air, and less compromised work performance. Intervention of dry air conditions by elevation of the indoor air humidity may be a non-pharmaceutical treatment of the risk of infection by reduced viability and transport of influenza virus. Relative humidity between 40 and 60% appears optimal for health, work performance, and lower risk of infection. Ventilation can reduce both acute and chronic health outcomes and improve work performance, because the exposure is reduced by the dilution of the indoor air pollutants (including pathogens, e.g., as virus droplets), and in addition to general emission source control strategies. Personal control of ventilation appears an important factor that influences the satisfaction of the thermal comfort due to its physical and positive psychological impact. However, natural ventilation or mechanical ventilation can become sources of air pollutants, allergens, and pathogens of outdoor or indoor origin and cause an increase in exposure. The "health-based ventilation rate" in a building should meet WHO's air quality guidelines and dilute human bio-effluent emissions to reach an acceptable perceived indoor air quality. Ventilation is a modifying factor that should be integrated with both the indoor air humidity and the room temperature in a strategic joint control to satisfy the perceived indoor air quality, health, working performance, and minimize the risk of infection.

Airborne fungal spore relationships with meteorological parameters and skin prick test results in Elazig, Turkey

BACKGROUND

Since fungi spores have high concentrations in the atmosphere during most of the year, they have an important place in respiratory allergies. In this regard, the preparation of calendars showing fungi spore loads for residential areas has much importance in the treatment of the patients. The first aim of this study was to present the airborne fungal spore research results from Eastern Anatolia in Turkey. Then, the mold spores' relationships with the meteorological parameters and skin prick test results were also evaluated. The presence of fungal spores was investigated using a volumetric spore trap in 2018 year.

METHODS

In this study, fungal spores within the atmosphere of the Elazığ city of Turkey was measured through the volumetric method, using a Lanzoni VPPS 2000 device (VPPS 2000 Lanzoni, Bologna, Italy), in 2018 year. Annual data of temperature, humidity, precipitation and wind speed were used for comparing meteorological data with airborne fungal spore counts. In addition, 637 children who were admitted to a pediatric allergy clinic with allergic complaints were enrolled in the study.

RESULTS

A total of 145,099 spores/m³ and 20 fungal taxa belonging to the molds were recorded. Ustilago was the predominant genus (18.10%), followed by Oidium (18.01%), Drechslera (12.82%), and Fusarium (11.60%), which were the most common fungal spores found in Elazig's atmosphere. The total mold spores in the atmosphere reached the highest level, with 28,153 spores/m³, in July (mid-summer). Moreover, we found a positive correlation between the mold spores and the temperature, but negative correlations with the humidity and wind speed. In the skin prick tests in the children with allergic complaints, we detected sensitization to Alternaria alternata in 4.4%, Cladosporium herbarum in 3.0%, Penicillium notatum in 1.4%, and Aspergillus fumigatus in 1.1%. Additionally, there was no correlation between fungal spore concentration in the atmosphere with fungal spores sensitization in the skin prick test.

CONCLUSIONS

This study was the first aerofungal survey of the Eastern Anatolia region in Turkey; therefore, new information has been introduced in the field of aerobiology in Turkey.

Indoor Air Quality in Passivhaus Dwellings: A Literature Review

Indoor air quality (IAQ) is a critical consideration in airtight buildings that depend on mechanical ventilation, such as those constructed to the Passivhaus standard. While previous reviews of IAQ on Passivhaus-certified buildings foccused on offices, this study examines residential buildings. A summary of data collection methods and pollutant concentrations is presented, followed by a critical discussion of the impact of Passivhaus design strategies on IAQ. This review indicates that IAQ in Passivhaus-certified dwellings is generally better than in conventional homes, but both occupant behaviour and pollution from outdoor sources play a significant role in indoor concentrations. Moreover, there are differences in data collection and reporting methods. Many of the available studies depend on short-term IAQ monitoring of less than two weeks, making it difficult to determine the longer impact of housing design on IAQ and occupants' well-being. There is also a lack of studies from non-European countries. Future research should focus on investigating associations between IAQ and Passivhaus design strategies in hot and humid climates, where evidence is particularly lacking. Further effort is also required to investigate potential links between occupant's perception of IAQ and physical exposure to indoor pollution. Finally, the lack of homogeneous monitoring and reporting methods for IAQ studies needs to be addressed.

Occupational exposure to pesticides and associated health effects among greenhouse farm workers

The number and production capacities of greenhouse farms have been increased across the globe, driven by an effort for addressing food security problems related to the rapid population growth and the effects of climate change. As a result, there was a large increase in the number of greenhouse farm workers who are typically involved in chemical preparations and pesticide sprayings, crop harvesting, and greenhouse maintenance activities. Considering the enclosed architecture of the greenhouse farm design and the frequent application of pesticides, the objective of this review was to characterize pesticide exposure levels and resultant health effects among greenhouse farm workers. While most health assessment studies were mainly based on self-reported symptoms, this review showed limited epidemiological and clinical studies on the assessment of the health effects of pesticide exposure on greenhouse workers' health. Reproductive disorders, respiratory symptoms, neurological symptoms, and skin irritations were the most reported health effects among greenhouse farm workers. Additionally, there were limited studies on respirable pesticide-borne fine and ultrafine particulate matters in greenhouse farms. Ventilation systems and indoor environmental conditions of greenhouse farms were not designed according to specifications of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). Among recommendations provided, long-term exposure assessments of pesticide effects on children born by greenhouse farm workers should be considered in future research. Also, compliance with ASHRAE indoor ventilation and environmental standards will be very important in reducing pesticide exposure and health effects among greenhouse farm workers.

Identifying and evaluating school environmental health indicators

Children's health, attendance, and academic performance may be affected by school environmental hazards. While prior studies evaluated home environment and health, few have evaluated indicators of school in-/outdoor environment and health. This study addresses this knowledge gap by systematically reviewing and evaluating outdoor and indoor indicators of school environment and student's health and performance in New York State (NYS). We also evaluate statistical methodologies to address highly correlated indicators and integrate multiple exposures. Multiple school environmental indicators were identified from various existing NYS datasets. We summarized data sources, completeness, geographic and temporal coverage, and data quality for each indicator. Each indicator was evaluated by scientific basis/relevance, analytic soundness/feasibility, and interpretation/utility, and validated using objective NYS data. Finally, advanced variable selection methods were described and discussed. We have identified and evaluated multiple school environmental health indicators. It was found that mold and moisture problems, ventilation problems, ambient ozone, and PM2.5 levels are among the top priorities of school environmental issues/indicators in NYS, which were also consistent while using NYS data. Choice of best variable selection method should be made based on the research questions and data characteristics. The school environmental health indicators identified, and variable selection methods evaluated, in this study could be used by other researchers to help school officials and policy makers initiate prevention programs.

Potted plants do not improve indoor air quality: a review and analysis of reported VOC removal efficiencies

Potted plants have demonstrated abilities to remove airborne volatile organic compounds (VOC) in small, sealed chambers over timescales of many hours or days. Claims have subsequently been made suggesting that potted plants may reduce indoor VOC concentrations. These potted plant chamber studies reported outcomes using various metrics, often not directly applicable to contextualizing plants' impacts on indoor VOC loads. To assess potential impacts, 12 published studies of chamber experiments were reviewed, and 196 experimental results were translated into clean air delivery rates (CADR, m³/h), which is an air cleaner metric that can be normalized by volume to parameterize first-order loss indoors. The distribution of single-plant CADR spanned orders of magnitude, with a median of 0.023 m³/h, necessitating the placement of 10-1000 plants/m² of a building's floor space for the combined VOC-removing ability by potted plants to achieve the same removal rate that outdoor-to-indoor air exchange already provides in typical buildings (~1 h^-1). Future experiments should shift the focus from potted plants' (in)abilities to passively clean indoor air, and instead investigate VOC uptake mechanisms, alternative biofiltration technologies, biophilic productivity and well-being benefits, or negative impacts of other plant-sourced emissions, which must be assessed by rigorous field work accounting for important indoor processes.

Indoor carbon dioxide concentrations in Croatian elementary school classrooms during the heating season

Aware that exposure to stuffy indoor air with high levels of carbon dioxide (CO2) is associated with higher absenteeism and reduced academic performance in school pupils, the World Health Organization (WHO) Regional Office for Europe initiated indoor air quality surveys in schools, including CO2 monitoring, to assess ventilation and exposure to stuffy air. Here we report the findings of the first such survey in Croatia. It was conducted in 60 classrooms of 20 urban and rural elementary schools throughout the country during the heating season. Measurements of CO2 levels showed that all 60 classrooms exceeded the international guidelines of 1938 mg/m3. Mean CO2 concentrations ranged from 2771 to 7763 mg/m3. The highest concentration measured in urban schools was 7763 mg/m3 and in rural schools 4771 mg/m3. Average CO2 levels were higher in continental schools (3683 mg/m3) than the coastal ones (3134 mg/m3), but all demonstrate poor ventilation during the heating season all over Croatia.

Indoor Environmental Quality Evaluation of Lecture Classrooms in an Institutional Building in a Cold Climate

In this paper, ventilation, indoor air quality (IAQ), thermal and acoustic conditions, and lighting were studied to evaluate the indoor environmental quality (IEQ) in an institutional building at the University of Alberta in Edmonton, Canada. This study examined IEQ parameters, including pressure, illuminance, acoustics, carbon dioxide (CO2) concentration, temperature, and humidity, with appropriate monitors allocated during a lecture (duration 50 min or 80 min) in four lecture classrooms repeatedly (N = 99) from October 2018 to March 2019 with the objectives of providing a comprehensive analysis of interactions between IEQ parameters. The classroom environments were maintained at 23 ± 1 °C and 33% ± 3% RH during two-season measurements. Indoor mean CO2 concentrations were 550–1055 ppm, and a mean sound level of 58 ± 3 dBA was observed. The air change rates were configured at 1.3–6.5 per hour based on continuous CO2 measurements and occupant loads in the lectures. A variance analysis indicated that the within-lecture classroom variations in most IEQ parameters exceeded between-lecture classrooms. A multilayer artificial neural network (ANN) model was developed on the basis of feedforward networks with a backpropagation algorithm. ANN results demonstrated the importance of the sequence of covariates on indoor conditions (temperature, RH, and CO2 level): Air change rate (ACR) > room operations (occupant number and light system) > outdoor conditions.

Impacts of air conditioning on air quality in tiny homes in Hong Kong

The risk of developing sick building syndrome is known to be higher in air-conditioned than naturally ventilated spaces. In Hong Kong, air conditioning (AC) is commonly used in homes to relieve summer heat stress. This study aims to assess the air quality impacts of AC in tiny homes called SDUs (sub-divided units). Poor ventilation and stronger heat stress in such informal housing could necessitate the use of AC. Predicted mean vote (PMV), CO, CO₂, PM10, PM2.5 and VOCs were continuously monitored for 72 h in eight SDUs. PMV was ≥2 ('warm') in 75% of the SDUs at sleeping time (after 22:00), implying an 80% dissatisfaction among the occupants. During AC use, the mean concentrations of CO and CO₂ increased from 220 to 905 μg/m³ (+312%) and from 920 to 1711 mg/m³ (+86%) respectively. The highest CO₂ level (3758 mg/m³) was observed in a 3-person household (one more than other SDUs). The overall impacts on PM10 (+4%) and PM2.5 (+19%) were relatively insignificant. Reduced ventilation in air-conditioned homes facilitated the accumulation of VOCs (mean change: +22%). The findings could inform building design and modify AC usage practice to improve the indoor environment.

High Life Study protocol: a cross-sectional investigation of the influence of apartment building design policy on resident health and well-being

INTRODUCTION

The rapid increase in apartment construction in Australia has raised concerns about the impacts of poorly designed and located buildings on resident health and well-being. While apartment design policies exist, their content varies across jurisdictions and evidence on their impact on health and well-being is lacking. This cross-sectional observational study (2017-2021) aims to generate empirical evidence to guide policy decisions on apartment development and help to create healthy, equitable higher-density communities. Objectives include to benchmark the implementation of health-promoting apartment design requirements and to identify associations between requirements and resident health and well-being outcomes.

METHODS AND ANALYSIS

Eligible buildings in three Australian cities with different apartment design guidelines will be stratified by area disadvantage and randomly selected (~n=99). Building architects, developers and local governments will be approached to provide endorsed development plans from which apartment and building design features will be extracted. Additional data collection includes a resident survey (~n=1000) to assess environmental stressors and health and well-being impacts and outcomes, and geographic information systems measures of the neighbourhood. The study has 85% power to detect a difference of 0.5 SD in the primary outcome of mental well-being (Warwick-Edinburgh Mental Well-being Scale) at a 5% level of significance. Analyses will compare policy compliance and health-promoting design features between cities and area disadvantage groups. Regression models will test whether higher policy compliance (overall and by design theme) is associated with better health and well-being, and the relative contribution of the neighbourhood context.

ETHICS AND DISSEMINATION

Human Research Ethics Committees of RMIT University (CHEAN B 21146-10/17) and the University of Western Australia (RA/4/1/8735) approved the study protocol. In addition to academic publications, the collaboration will develop specific health-promoting indicators to embed into the monitoring of apartment design policy implementation and impact, and co-design research dissemination materials to facilitate uptake by decision makers.

The Impact of Air Pressure Conditions on the Performance of Single Room Ventilation Units in Multi-Story Buildings

Single room ventilation units with heat recovery is one of the ventilation solutions that have been used in renovated residential buildings in Estonia. In multi-story buildings, especially in a cold climate, the performance of units is affected by the stack effect and wind-induced pressure differences between the indoor and the outdoor air. Renovation of the building envelope improves air tightness and the impact of the pressure conditions is amplified. The aim of this study was to predict the air pressure conditions in typical renovated multi-story apartment buildings and to analyze the performance of room-based ventilation units. The field measurements of air pressure differences in a renovated 5-story apartment building during the winter season were conducted and the results were used to simulate whole-year pressure conditions with IDA-ICE software. Performance of two types of single room ventilation units were measured in the laboratory and their suitability as ventilation renovation solutions was assessed with simulations. The results show that one unit stopped its operation as a heat recovery ventilator. In order to ensure satisfactory indoor climate and heat recovery using wall mounted units the pressure difference values were determined and proposed for correct design.

Indoor environmental quality, occupant satisfaction, and acute building-related health symptoms in Green Mark-certified compared with non-certified office buildings

Indoor environmental quality (IEQ) has become an important component of green building certification schemes. While green buildings are expected to provide enhanced IEQ, higher occupant satisfaction, and less risks of occupant health when compared with non-green buildings, the literature suggests inconsistent evidence due to diverse research design, small sample size, and weak statistical analysis. This study compared several outcomes pertinent to IEQ performance in green and non-green office buildings in Singapore. Adopting a cross-sectional study design, objective measurements were taken in eight green and six non-green buildings, and satisfaction and acute health symptom risks of 367 occupants were obtained. Green buildings exhibited lower concentration of PM2.5, bacteria, and fungi and maintained temperature and humidity more consistently compared to non-green counterparts. The mean ratings for satisfaction with temperature, humidity, lighting level, air quality, and indoor environment were higher in green buildings (with statistical significance P < 0.05). There was statistically significant reduction in risk of occupants having headache, unusual fatigue, and irritated skin in green buildings. Although matching of buildings and occupant characteristics, survey participation bias, and sampling duration (a 1-week snapshot) of IEQ monitoring remain as limitations, this study offered positive association of green buildings with qualitatively and quantitatively measured performance of IEQ.

BTEX in indoor air of beauty salons: Risk assessment, levels and factors influencing their concentrations

Concentrations of benzene, toluene, ethylbenzene, and xylene (BTEX) were investigated in indoor air quality of 50 beauty salons in Ardabil, Iran (2017). Ten liters of air samples were collected from each salons regarding the recommended method and analyzed by GC-FID for BTEX concentration. Also, structural and operational conditions of the salons were studied with a self-designed questioner. The results of this study show that the mean concentration of benzene (32.40 ± 26.38) higher than the recommended levels by Health Canada, ANSES and HKSAR. Among the BTEX, ethylbenzene (62.38 ± 32.37) has the most concentrations in the salons. Subsequently, the cancer risk values in different age groups of birth to <6, 6 to <21, and 21 to <81 for benzene (1.83 × 10^-3, 2.76 × 10^-4 and 1.50 × 10^-4, respectively) and ethylbenzene (4.9 × 10^-4, 7.30 × 10^-5 and 3.52 × 10^-5, respectively) for long time exposure were drastically higher than the recommended levels. The results showed that the benzene concentration is significantly influenced by the structural and operational conditions of type of ventilation system, area of the salons, the number of people in the salon, number of services in the salons, and while doing of bridal makeup.

Healthy Indoor Environments: The Need for a Holistic Approach

Indoor environments have a large impact on health and well-being, so it is important to understand what makes them healthy and sustainable. There is substantial knowledge on individual factors and their effects, though understanding how factors interact and what role occupants play in these interactions (both causative and receptive) is lacking. We aimed to: (i) explore interactions between factors and potential risks if these are not considered from holistic perspective; and (ii) identify components needed to advance research on indoor environments. The paper is based on collaboration between researchers from disciplines covering technical, behavioural, and medical perspectives. Outcomes were identified through literature reviews, discussions and workshops with invited experts and representatives from various stakeholder groups. Four themes emerged and were discussed with an emphasis on occupant health: (a) the bio-psycho-social aspects of health; (b) interaction between occupants, buildings and indoor environment; (c) climate change and its impact on indoor environment quality, thermal comfort and health; and (d) energy efficiency measures and indoor environment. To advance the relevant research, the indoor environment must be considered a dynamic and complex system with multiple interactions. This calls for a transdisciplinary and holistic approach and effective collaboration with various stakeholders.

How home ventilation rates affect health: A literature review

This paper reviews studies of the relationships between ventilation rates (VRs) in homes and occupant health, primarily respiratory health. Five cross-sectional studies, seven case-control studies, and eight intervention studies met inclusion criteria. Nearly all studies controlled for a range of potential confounders and most intervention studies included placebo conditions. Just over half of studies reported one or more statistically significant (SS) health benefits of increased VRs. Wheeze was most clearly associated with VR. No health outcomes had SS associations with VRs in the majority of statistical tests. Most studies that reported SS health benefits from increased VRs also had additional health outcomes that did not improve with increased VRs. Overall, the number of SS improvements in health with increased VRs exceeded the anticipated chance improvements by approximately a factor of seven. The magnitude of the improvements in health outcomes with increased VRs ranged from 20% to several-fold improvements. In summary, the available research indicates a tendency for improvements in respiratory health with increased home VRs; however, health benefits do not occur consistently and other exposure control measures should be used together with ventilation. The research did not enable identification of a threshold VR below which adverse health effects occur.

Ventilation Positive Pressure Intervention Effect on Indoor Air Quality in a School Building with Moisture Problems

This case study investigates the effects of ventilation intervention on measured and perceived indoor air quality (IAQ) in a repaired school where occupants reported IAQ problems. Occupants’ symptoms were suspected to be related to the impurities leaked indoors through the building envelope. The study’s aim was to determine whether a positive pressure of 5–7 Pa prevents the infiltration of harmful chemical and microbiological agents from structures, thus decreasing symptoms and discomfort. Ventilation intervention was conducted in a building section comprising 12 classrooms and was completed with IAQ measurements and occupants’ questionnaires. After intervention, the concentration of total volatile organic compounds (TVOC) and fine particulate matter (PM_2.5) decreased, and occupants’ negative perceptions became more moderate compared to those for other parts of the building. The indoor mycobiota differed in species composition from the outdoor mycobiota, and changed remarkably with the intervention, indicating that some species may have emanated from an indoor source before the intervention.

Perceived indoor air quality and its relationship to air pollutants in French dwellings

Perception of indoor air quality (PIAQ) was evaluated in a nationwide survey of 567 French dwellings, and this survey was combined with measurements of gaseous and particulate matter (PM₁₀ and PM_2.5 ) indoor air pollutants and indoor climate parameters. The perception was assessed on a nine-grade scale by both the occupants of the dwellings and the inspectors who performed the measurements. The occupants perceived the air quality in their homes as more pleasant than the inspectors. The inspectors perceived the air quality as more unpleasant in dwellings in which the residents smoked indoors. Significant associations between PIAQ and indoor air pollutant concentrations were observed for both the inspectors and, to a lesser extent, the occupants. Introducing confounding parameters, such as building and personal characteristics, into a multivariate model suppressed most of the observed bivariate correlations and identified the tenure status of the occupants and their occupation as the parameters that most influenced their PIAQ. For the inspectors, perceived air quality was affected by the presence of smokers, the season, the type of ventilation, retrofitting, and the concentrations of acetaldehyde and acrolein.

Reflections on the history of indoor air science, focusing on the last 50 years

The scientific articles and Indoor Air conference publications of the indoor air sciences (IAS) during the last 50 years are summarized. In total 7524 presentations, from 79 countries, have been made at Indoor Air conferences held between 1978 (49 presentations) and 2014 (1049 presentations). In the Web of Science, 26 992 articles on indoor air research (with the word "indoor" as a search term) have been found (as of 1 Jan 2016) of which 70% were published during the last 10 years. The modern scientific history started in the 1970s with a question: "did indoor air pose a threat to health as did outdoor air?" Soon it was recognized that indoor air is more important, from a health point of view, than outdoor air. Topics of concern were first radon, environmental tobacco smoke, and lung cancer, followed by volatile organic compounds, formaldehyde and sick building syndrome, house dust-mites, asthma and allergies, Legionnaires disease, and other airborne infections. Later emerged dampness/mold-associated allergies and today's concern with "modern exposures-modern diseases." Ventilation, thermal comfort, indoor air chemistry, semi-volatile organic compounds, building simulation by computational fluid dynamics, and fine particulate matter are common topics today. From their beginning in Denmark and Sweden, then in the USA, the indoor air sciences now show increasing activity in East and Southeast Asia.

SBS symptoms in relation to dampness and ventilation in inspected single-family houses in Sweden

Purpose

To investigate the relationships between symptoms compatible with the sick building syndrome (SBS) in adults and building dampness and ventilation in single-family houses.

Methods

Within the Swedish BETSI study, a national sample of single-family houses were inspected by professional building experts, and adults living in the houses answered a questionnaire on SBS. Relationships between building factors and SBS were analysed using logistic regression.

Results

Of the respondents, 23% reported having had weekly SBS symptoms during the last three months. A large proportion of houses exhibited building or construction problems. In total, 40% of houses had dampness problems in the foundation, and this was related to a higher prevalence of both mucous and dermal symptoms, and any SBS symptoms. Furthermore, high air humidity was related to more symptoms, with the relationship with absolute humidity being stronger than that with relative humidity or moisture load. Symptoms were also more prevalent in houses with a high U value, reflecting a poor thermal insulation. Compared to natural ventilation, living in a house with mechanical supply and exhaust ventilation was related to a lower prevalence of general symptoms and any SBS symptoms, but there were only weak associations between measured air exchange rate and symptoms.

Conclusions

A large proportion of single-family houses have dampness problems in the foundation, and pollutants may enter the living space of the house and affect the health of the occupants. Furthermore, absolute air humidity should be measured more often in indoor air studies.

Defining Significant Events for Neonatal and Pediatric Transport: Results of a Combined Delphi and Consensus Meeting Process

Objective  To develop standardized definitions for a list of indicators that represent significant events during pediatric transport, which were previously identified by a national Delphi study. Methods  We designed a three-phase consensus process that applied Delphi methodology to a combination of electronic questionnaires and a live consensus meeting. Results  Thirty-one pediatric transport experts evaluated a total of 59 indicators. Twenty-four indicators represented events or interventions that did not require definition. One indicator was removed from the list. Definitions for the remaining 34 indicators were developed. Conclusion  This standardized indicator list is intended for application to quality improvement and clinical research initiatives.

Indoor inhalation intake fractions of fine particulate matter: review of influencing factors

Exposure to fine particulate matter (PM_2.5 ) is a major contributor to the global human disease burden. The indoor environment is of particular importance when considering the health effects associated with PM_2.5 exposures because people spend the majority of their time indoors and PM_2.5 exposures per unit mass emitted indoors are two to three orders of magnitude larger than exposures to outdoor emissions. Variability in indoor PM_2.5 intake fraction (iF_in,total ), which is defined as the integrated cumulative intake of PM_2.5 per unit of emission, is driven by a combination of building-specific, human-specific, and pollutant-specific factors. Due to a limited availability of data characterizing these factors, however, indoor emissions and intake of PM_2.5 are not commonly considered when evaluating the environmental performance of product life cycles. With the aim of addressing this barrier, a literature review was conducted and data characterizing factors influencing iF_in,total were compiled. In addition to providing data for the calculation of iF_in,total in various indoor environments and for a range of geographic regions, this paper discusses remaining limitations to the incorporation of PM_2.5 -derived health impacts into life cycle assessments and makes recommendations regarding future research.

Concentrations and identification of culturable airborne fungi in underground stations of the Seoul metro

The purpose of this study was to measure the culturable airborne fungi (CAF) concentrations in the underground subway stations of Seoul, Korea at two time points. This study measured the CAF concentrations in enclosed environments at 16 underground stations of the Seoul Metro in 2006 and 2013 and investigated the effects of various environmental factors, including the presence of platform screen doors, temperature, relative humidity, and number of passengers. CAF concentrations at the stations in 2006 were significantly higher than that at the same stations in 2013 (p < 0.001). Furthermore, there was a significant correlation between CAF concentration and relative humidity (r = 0.311, p < 0.05). Geotrichum and Penicillium were the predominant genera. The CAF concentrations in stations with an operating supply air were significantly higher than that in stations with no supply air (p < 0.001). Therefore, it is recommended that special attention be given to stations with clean supplied air to improve the indoor air quality of these subway stations.

The economic benefits of reducing the levels of nitrogen dioxide (NO2) near primary schools: The case of London

Providing a healthy school environment is a priority for child health. The aim of this study is to develop a methodology that allows quantification of the potential economic benefit of reducing indoor exposure to nitrogen dioxide (NO2) in children attending primary schools. Using environmental and health data collected in primary schools in London, this study estimates that, on average, 82 asthma exacerbations per school can be averted each year by reducing outdoor NO2 concentrations. The study expands upon previous analyses in two ways: first it assesses the health benefits of reducing children's exposure to indoor NO2 while at school, second it considers the children's perspective in the economic evaluation. Using a willingness to pay approach, the study quantifies that the monetary benefits of reducing children's indoor NO2 exposure while at school would range between £2.5 k per school if a child's perspective based on child's budget is adopted up to £60 k if a parent's perspective is considered. This study highlights that designers, engineers, policymakers and stakeholders need to consider the reduction of outdoor pollution, and particularly NO2 levels, near primary schools as there may be substantial health and monetary benefits.

Case Study of Volatile Organic Compounds in Indoor Air of a House before and after Repair where Sick Building Syndrome Occurred

A housewife in her late thirties, mother of two children, had an indefinite complaint about the indoor air quality of her house. Inspectors from a public health center treating the housewife's complaint quantified formaldehyde (FA) in high concentration exceeding Japanese national guideline of FA in some rooms of the house. We also determined FA and total volatile organic compounds (TVOCs) in higher concentrations more than the national guidelines. Remodeling of the house was performed to improve the air quality as follows. Vinyl wallpaper was exchanged to plant made paper, plywood made doors were exchanged to pure wood made doors, plywood stairs were covered with plant cork and so on. After remodeling the house, we measured the concentrations of FA and TVOCs again. The concentrations of the chemicals in the indoor air decreased which approve effectiveness of the remodeling. Moreover complaints of the housewife lessened. This also proved the effectiveness of the remodeling. Four years after the inspection, we visited the house again and found that the concentration of FA in the house was still lower than that of national guideline. The housewife was evaluated in a good healthy condition by her answers to our questions related to indoor air quality, daily life, physical condition, and so on.

Association Between Markers of Classroom Environmental Conditions and Teachers' Respiratory Health

BACKGROUND

Studies have assessed health in schoolchildren. Less is known about the environmental and occupational health of teachers.

METHODS

A cross-sectional survey of teachers was conducted in 24 randomly selected public elementary schools. Questionnaire included sociodemographic information, healthcare, school conditions, and health outcomes. Chi-square and logistic regression were used to analyze bivariate relationships. Multivariable logistic regression model was created for each health outcome, adjusted for sex and smoking to calculate estimates of association (OR) for variables that were significant in bivariate analysis.

RESULTS

Response rate was 71.2 % (N = 797). Classroom conditions significantly associated with respiratory symptoms included having no windows or windows that do not open were associated with asthma or colds (OR 2.0); carpeting was associated with having asthma, itchy eyes, and eye irritation (OR 1.9); mold or water damage was associated with respiratory infections, eye irritation (OR 2.1), nasal congestion (OR 2.4), and sore throat (OR 2.7); visible dust was associated with frequent colds (OR 2.2), nasal congestion (OR 1.7), and sore throat (1.9).

CONCLUSIONS

Asthma, respiratory infections, colds, eye irritation, nasal congestion, and sore throat were associated with the classroom environment. Results indicate that the school environment could affect teachers' respiratory health. Further assessments are necessary to establish causation.