Ventilation rates and health: multidisciplinary review of the scientific literature

Prenatal risk factors of indoor environment and incidence of childhood eczema in the Japan Environment and Children's Study

The quality of indoor environment is a risk factor for early childhood eczema and atopic dermatitis; however, its influence during pregnancy on childhood eczema in Japan has not been investigated. In this study, we aimed to determine the indoor environmental factors that are associated with eczema in children up to 3 years of age, using national birth cohort data from the Japan Environment and Children's Study (JECS). Information on indoor environments and eczema symptoms until 3 years of age was collected using self-administered questionnaires to the mothers. A total of 71,883 and 58,639 mother-child pairs at 1.5- and 3-years-old, respectively, were included in the former analyses. To account for prenatal indoor risk factors, 17,568 (1.5-years-old) and 7063 (3-years-old) children without indoor mold and/or ETS exposure were included in the final analysis. A higher mold index, gas heater use, parquet flooring use, and frequent insecticide use showed significantly increased risks for childhood eczema up to 3 years of age. These associations were consistent after stratification analysis among children whose parents did not have a history of allergies. The updated WHO guidelines on indoor air quality should be implemented based on recent findings regarding the effects of prenatal exposure to indoor dampness on health effects of children further in life, including asthma, respiratory effects, eczema, and other immunological effects.

Research on the cascading mechanism of "urban built environment-air pollution-respiratory diseases": a case of Wuhan city

Background

Most existing studies have only investigated the direct effects of the built environment on respiratory diseases. However, there is mounting evidence that the built environment of cities has an indirect influence on public health via influencing air pollution. Exploring the "urban built environment-air pollution-respiratory diseases" cascade mechanism is important for creating a healthy respiratory environment, which is the aim of this study.

Methods

The study gathered clinical data from 2015 to 2017 on patients with respiratory diseases from Tongji Hospital in Wuhan. Additionally, daily air pollution levels (sulfur dioxide (SO2), nitrogen dioxide (NO2), particulate matter (PM2.5, PM10), and ozone (O3)), meteorological data (average temperature and relative humidity), and data on urban built environment were gathered. We used Spearman correlation to investigate the connection between air pollution and meteorological variables; distributed lag non-linear model (DLNM) was used to investigate the short-term relationships between respiratory diseases, air pollutants, and meteorological factors; the impacts of spatial heterogeneity in the built environment on air pollution were examined using the multiscale geographically weighted regression model (MGWR).

Results

During the study period, the mean level of respiratory diseases (average age 54) was 15.97 persons per day, of which 9.519 for males (average age 57) and 6.451 for females (average age 48); the 24 h mean levels of PM10, PM2.5, NO2, SO2 and O3 were 78.056 μg/m3, 71.962 μg/m3, 54.468 μg/m3, 12.898 μg/m3, and 46.904 μg/m3, respectively; highest association was investigated between PM10 and SO2 (r = 0.762, p < 0.01), followed by NO2 and PM2.5 (r = 0.73, p < 0.01), and PM10 and PM2.5 (r = 0.704, p < 0.01). We observed a significant lag effect of NO2 on respiratory diseases, for lag 0 day and lag 1 day, a 10 μg/m3 increase in NO2 concentration corresponded to 1.009% (95% CI: 1.001, 1.017%) and 1.005% (95% CI: 1.001, 1.011%) increase of respiratory diseases. The spatial distribution of NO2 was significantly influenced by high-density urban development (population density, building density, number of shopping service facilities, and construction land, the bandwidth of these four factors are 43), while green space and parks can effectively reduce air pollution (R2 = 0.649).

Conclusion

Previous studies have focused on the effects of air pollution on respiratory diseases and the effects of built environment on air pollution, while this study combines these three aspects and explores the relationship between them. Furthermore, the theory of the "built environment-air pollution-respiratory diseases" cascading mechanism is practically investigated and broken down into specific experimental steps, which has not been found in previous studies. Additionally, we observed a lag effect of NO2 on respiratory diseases and spatial heterogeneity of built environment in the distribution of NO2.

Health benefits to vulnerable populations by meeting particle-level guidelines inside schools with different ventilation conditions

We conducted simultaneous real-time measurements for particles on the premises of four schools, two of which were naturally ventilated (NV) and two mechanically ventilated (MV) in Kanpur, India. Health to school children from reduced particle levels inside classrooms simulated to the lowest acceptable levels (ISHRAE Class C: PM10 ≤ 100 µg/m3 & PM2.5 ≤ 25 µg/m3) using air filters were examined. Lung deposition of particles was used as a proxy for health impacts and calculated using the MPPD model. The particle levels in all classrooms were above the baseline, with NV classrooms having higher particle masses than MV classrooms: 72.16% for PM1, 74.66% for PM2.5, and 85.17% for PM10. Our calculation reveals a whooping reduction in particles deposited in the lungs (1512% for PM10 and 1485% for PM2.5) in the case of the NV classrooms. Results highlight unhealthy air inside classrooms and suggest urgent interventions, such as simple filtration techniques, to achieve acceptable levels of particles inside schools.

Living in an Intimate Partner Violence Shelter During a Pandemic: Perspectives from Advocates and Survivors

PURPOSE

With state-wide quarantine policies during the COVID-19 pandemic like those implemented in the state of Texas, intimate partner violence (IPV) shelter staff were forced to incorporate new safety measures to keep survivors and advocates safe. To understand the impact of these adaptations fully, authors interviewed shelter staff and residents to capture both of their experiences living and working in the same shelter during the height of the coronavirus pandemic (summer 2020) to understand how changes in policy and procedure in shelters impacted survivors and advocates.

MATERIALS AND METHODS

A qualitative phenomenological design was utilized to collect and analyze data from 10 staff and 10 survivors to develop both a textual and a structural description of participant experiences living in an IPV shelter.

RESULTS

The current study captured the survivors' and advocates' perspectives related to the 1) vacillating views of shelter social distancing and quarantine policies, 2) shelter occupancy and staffing unpredictability, 3) the broader challenges related to environmental stressors and 4) mobility challenges.

DISCUSSION

Results of this study highlight factors related to interpersonal relationships within the shelter and structural factors of shelter which contributed to stress for participants.

CONCLUSION

The coronavirus is continuing to present challenges for shelters. Implications can be drawn from provider and client experiences that can inform policies and procedures for future health crises, including the need to mitigate environmental stress and transportation challenges, as well as considerations for maintaining social support should social distancing be necessary in future epidemics.

Holistic understanding of ventilation rate in occupational health risk control

Throughout the history of occupational health risk control, ventilation has been implemented widely as a tried-and-true method to reduce exposure intensity to airborne contaminants. Proper determination of the ventilation rate merits careful consideration when addressing concerns directed toward occupational health and indoor air quality in commercial buildings, albeit this does not translate well among the current engineering and scientific community. This article aims to facilitate a better understanding and proper determination of ventilation rates as a countermeasure for occupational health risk control. To that end, guidance is provided to select the appropriate ventilation rate for nonpandemic versus pandemic scenarios in terms of pertinent regulatory/professional codes and mathematical modeling tools. Limitations and assumptions of the models are summarized to facilitate proper application. Furthermore, the emerging DNA-based aerosol tracing technology, which helps to verify ventilation efficacy, is discussed.

Air change rates and infection risk in school environments: Monitoring naturally ventilated classrooms in a northern Italian urban context

The importance of building ventilation in avoiding long-distance airborne transmission has been highlighted with the advent of the COVID-19 pandemics. Among others, school environments, in particular classrooms, present criticalities in the implementation of ventilation strategies and their impact on indoor air quality and risk of contagion. In this work, three naturally ventilated school buildings located in northern Italy have undergone monitoring at the end of the heating season. Environmental parameters, such as CO2 concentration and indoor/outdoor air temperature, have been recorded together with the window opening configurations to develop a two-fold analysis: i) the estimation of real air change rates through the transient mass balance equation method, and ii) the individual infection risk via the Wells-Riley equation. A strong statistical correlation has been found between the air change rates and the windows opening configuration by means of a window-to-volume ratio between the total opening area and the volume of the classroom, which has been used to estimate the individual infection risk. Results show that the European Standard recommendation for air renewal could be achieved by a window opening area of at least 1.5 m2, in the most prevailing Italian classrooms. Furthermore, scenarios in which the infector agent is a teacher show higher individual infection risk than those in which the infector is a student. In addition, the outcomes serve school staff as a reference to ensure adequate ventilation in classrooms and keep the risk of infection under control based on the number of the students and the volume of the classroom.

Childhood pneumonia in Beijing: Associations and interactions among selected demographic and environmental factors

Among infectious diseases, pneumonia is the greatest cause of mortality in children less than 5 years old. Approximately 27% of Beijing's 3-8 year-old children have had pneumonia at least once. The sole reservoir of pneumonia pathogens is the human nasopharynx. We investigated associations and interactions among two kinds of environmental risk factors: i) airborne pathogens, namely closed bedroom window and shared bedroom and ii) pollutants, namely traffic pollution and environmental tobacco smoke (ETS). We evaluated breastfeeding's (BF) protective value against childhood pneumonia. The database consists of responses to a questionnaire in a cross-sectional study. Crude and adjusted Odds Ratios were assessed independently for each risk factor. Combinations of the studied risk factors were analyzed using multivariate logistic regression. Risk factors were evaluated for interactions on the additive scale using the metrics Relative Excess Risk due to Interaction (RERI), Attributable Proportion (AP) and Synergy Index (S). All independent risk factors were significant for children's pneumonia. We also found evidence of possible synergistic interaction between pairs of risk factors that was stronger when one of the risk factors was a closed bedroom window. Remarkably, window opening was associated with reduced risk of pneumonia for children living near heavy traffic pollution. Longer duration BF was more protective than shorter, and exclusive BF was more protective than partial BF against childhood pneumonia. In conclusion, low ventilation (closed bedroom windows), shared bedroom, ETS, and traffic exposure were associated with increased risk of pneumonia. Exclusive BF for more than six months had the greatest protective value against pneumonia.

Crosscutting of the pollutants and building ventilation systems: a literature review

Considering the time spent in enclosed environments, it is essential to study the relationship between pollutants and building ventilation systems to find whether the types and levels of pollutants and greenhouse gasses, which are expected to be exhaled through ventilation systems into the atmosphere, have been adequately evaluated. We propose the hypothesis that the exhaled air from residential buildings contains pollutants that may become another source of contamination affecting urban air quality and potentially contributing to climate drivers. Thus, the main goal of this article is to present a cross-review of the identification of pollutants expected to be exhaled through ventilation systems in residential buildings. This approach has created the concept of "exhalation of buildings" a new concept enclosed within the research project in which this article is included. We analyze the studies related to the most significant pollutants found in buildings and the studies about the relation of buildings' ventilation systems with such pollutants. Our results show that, on the one hand, the increase in the use of mechanical ventilation systems in residential buildings has been demonstrated to enhance the ventilation rate and generally improve the indoor air quality conditions. But no knowledge could be extracted about the corresponding environmental cost of this improvement, as no systematic data were found about the total mass of contaminants exhaled by those ventilation systems. At the same time, no projects were found that showed a quantitative study on exhalation from buildings, contrary to the existence of studies on pollutants in indoor air.

Determinants Analysis Regarding Household Chemical Indoor Pollution

Indoor household pollution is not yet sufficiently studied in the general population. Over 4 million people die prematurely every year due to air pollution in households. This study aimed to propose quantitative data research through the administration of a KAP (Knowledge, Attitudes, and Practices) Survey Questionnaire. This cross-sectional study administered questionnaires to adults from the metropolitan city of Naples (Italy). Three Multiple Linear Regression Analyses (MLRA) were developed, including Knowledge, Attitudes, and Behavior regarding household chemical air pollution and the related risks. One thousand six hundred seventy subjects received a questionnaire to be filled out and collected anonymously. The mean age of the sample was 44.68 years, ranging from 21-78 years. Most of the people interviewed (76.13%) had good attitudes toward house cleaning, and 56.69% stated paying attention to cleaning products. Results of the regression analysis indicated that positive attitudes were significantly higher among subjects who graduated, with older age, male and non-smokers, but they were correlated with lower knowledge. In conclusion, a behavioral and attitudinal program targeted those with knowledge, such as younger subjects with high educational levels, but do not engage in correct practices towards household indoor chemical pollution.

Kitchen ventilation attenuated the associations of solid fuel use and long duration for cooking with the increased prevalence of normocytic anemia

Evidence on the potential risk factors of normocytic anemia, the most prevalent morphology subtype of anemia, was scarce to date. The purpose of this study is to investigate the association of cooking fuel use or daily cooking duration with normocytic anemia and further explore the modification effect of mechanical ventilation. Participants totaling 29,448 from the Henan Rural Cohort were included in this study. Normocytic anemia was defined by hemoglobin (based on the World Health Organization criteria) and mean corpuscular volume. Cooking-related data was collected by questionnaire, and the average daily cooking duration was calculated by the weekly cooking frequency and the cooking duration of each meal. Logistic regression models were employed to derive the combined and independent associations of cooking fuel type and daily cooking duration with normocytic anemia and the modification effect of ventilation. Compared with people who never cooked, both clean fuel and solid fuel users were significantly associated with increased prevalent normocytic anemia [OR (95% CI) = 1.196 (1.014, 1.411) and 1.335 (1.105, 1.614), respectively], and the effect estimates on normocytic anemia risk were 1.260 (1.043, 1.523), 1.320 (1.104, 1.578), and 1.310 (1.081, 1.587) in participants who daily cooked < 1 h/day, 1-2 h/day, and ≥ 2 h/day, respectively. These relationships were attenuated in subjects with mechanical ventilation (All P < 0.05). Cooking with solid fuel or for a long duration are independently associated with prevalent normocytic anemia in rural population, and mechanical ventilation could attenuate these associations. Future efforts to reduce the burden of anemia could target the universal use of ventilation and solid fuel use or cooking duration reduction.Clinical trial registration: The Henan Rural Cohort Study has been registered at Chinese Clinical Trial Register (Registration number: ChiCTR-OOC-15006699). Date of registration: 06 July, 2015. http://www.chictr.org.cn/showproj.aspx?proj=11375.

Association of household air pollution with glucose homeostasis markers in Chinese rural women: Effect modification of socioeconomic status

BACKGROUND

Socioeconomic status (SES) was a crucial influencing factor of household air pollution (HAP). However, few studies have explored the potential effect modification of SES on the associations of HAP with type 2 diabetes mellitus (T2DM) and glucose homeostasis.

METHODS

A total of 20900 participants were obtained from the Henan Rural Cohort. HAP reflected by cooking fuel type and cooking duration was assessed via questionnaire. SES was evaluated by two dimensions: educational level and average monthly income. Associations of cooking fuel type, cooking duration with T2DM and glucose homeostasis indices (insulin, fasting plasma glucose (FPG), and HOMA-β) were assessed by the generalized linear model. Analyses were also conducted in different SES groups to explore the potential effect modification.

RESULTS

Significant negative association of cooking fuel type and cooking duration with T2DM, FPG, and HOMA-β was not observed. However, cooking with solid fuel and long-duration cooking were associated with decreased insulin level in women, and the adjusted coefficients were - 0.35 (95% confidence interval (95% CI): - 0.53, - 0.17) and - 0.36 (95% CI: -0.50, -0.21), respectively. Results from stratified analyses showed that these associations were more prominent in women with low average monthly income, with corresponding coefficient of - 0.57 (95% CI: -0.77, -0.37) for cooking with solid fuel and - 0.34 (95% CI: -0.52, -0.16) for long-duration cooking. Among women with low average monthly income, the largest decreased insulin level was observed in those who cooked with solid fuel, long-duration and poor kitchen ventilation, while the negative association of cooking fuel type and cooking duration with insulin level was slightly alleviated in the good kitchen ventilation group.

CONCLUSIONS

Low average monthly income aggravated the negative association of HAP and insulin level among rural women, while improving kitchen ventilation may be a practical intervention.

TRAIL REGISTRATION

The Henan Rural Cohort Study has been registered at Chinese Clinical Trial Register (Registration number: ChiCTR-OOC-15006699). Date of registration: 06 July, 2015. http://www.chictr.org.cn/showproj.aspx?proj=11375.

Symptoms and oxylipins in plasma before and after exposure to rooms in which individuals have both experienced and not experienced building-related symptoms - an exploratory study

The aim of this study was to investigate if there are differences in symptom ratings and plasma concentrations of oxylipins as a measure of acute inflammation between individuals with building-related symptoms (BRS) and referents during exposure to rooms where people experienced BRS and rooms where they did not experience BRS. Medically examined individuals with BRS and healthy, age and sex matched referents working in the same building were exposed for 60 min. Ratings of symptoms and collection of blood to measure oxylipins in plasma were performed before and after each exposure. Individuals with BRS reported more symptoms (mostly mucosal) than the referents in the problem rooms and there was a tendency towards a difference between the groups in concentration of metabolites from the cyclooxygenase pathway (COX). The mean reported intensity of symptoms among all participants was also found to be positively correlated with both COX and lipoxygenase (LOX-15) oxylipins in problem rooms.

Airborne transmission of biological agents within the indoor built environment: a multidisciplinary review

The nature and airborne dispersion of the underestimated biological agents, monitoring, analysis and transmission among the human occupants into building environment is a major challenge of today. Those agents play a crucial role in ensuring comfortable, healthy and risk-free conditions into indoor working and leaving spaces. It is known that ventilation systems influence strongly the transmission of indoor air pollutants, with scarce information although to have been reported for biological agents until 2019. The biological agents' source release and the trajectory of airborne transmission are both important in terms of optimising the design of the heating, ventilation and air conditioning systems of the future. In addition, modelling via computational fluid dynamics (CFD) will become a more valuable tool in foreseeing risks and tackle hazards when pollutants and biological agents released into closed spaces. Promising results on the prediction of their dispersion routes and concentration levels, as well as the selection of the appropriate ventilation strategy, provide crucial information on risk minimisation of the airborne transmission among humans. Under this context, the present multidisciplinary review considers four interrelated aspects of the dispersion of biological agents in closed spaces, (a) the nature and airborne transmission route of the examined agents, (b) the biological origin and health effects of the major microbial pathogens on the human respiratory system, (c) the role of heating, ventilation and air-conditioning systems in the airborne transmission and (d) the associated computer modelling approaches. This adopted methodology allows the discussion of the existing findings, on-going research, identification of the main research gaps and future directions from a multidisciplinary point of view which will be helpful for substantial innovations in the field.

Effects of occupant behaviors on perceived dormitory air quality and sick building syndrome symptoms among female college students

We performed a cross-sectional survey of 2143 female students in a university in Tianjin, China regarding perceived air quality (PAQ) and sick building syndrome (SBS) symptoms in the student dormitory. The prevalence of general, mucosal, and skin symptoms was 22.1%, 21.9%, and 26.3%, respectively. The three most prevalent PAQ complaints were "dry air" (48.9% often), "stuffy odor" (18.2%), and "other unpleasant odors" (5.1%), and they were significant risk factors for 11-12 out of 12 SBS symptoms (adjusted odds ratios [AOR]: 1.6-5.8). Survey data of 1471 undergraduates, whose dorms were of uniform layout and furnishing, were used to further investigate the influences of occupancy level and occupant behaviors on PAQ and SBS symptoms. Frequent use of air freshener/perfume was a significant risk factor for "dry air," less frequent room cleaning and higher occupancy density were significant risk factors for "stuffy odor," and less natural ventilation was a significant risk factor for both "stuffy odor" and "pungent odor." These factors were also significantly associated with some SBS symptoms. In particular, the use of air freshener/perfume exhibited a significant dose-response pattern with "fatigue" (sometimes: AOR 1.3; often: AOR 2.0) and with "irritated, stuffy, or runny nose" (sometimes: AOR 1.6; often: AOR 2.2).

Exposure at the indoor water-air interface: Fill water constituents and the consequent air emissions from ultrasonic humidifiers: A systematic review

This systematic review investigates the emissions from ultrasonic humidifiers (e.g., cool mist humidifiers) within indoor air environments, namely soluble and insoluble metals and minerals as well as microorganisms and one organic chemical biocide. Relationships between ultrasonic humidifier fill water quality and the emissions in indoor air are studied, and associated potential adverse health outcomes are discussed. Literature from January 1, 1980, to February 1, 2022, was searched from online databases of PubMed, Web of Science, and Scopus to produce 27 articles. The results revealed clear positive proportional relationships of the concentration of microorganisms and soluble metals/minerals between fill water qualities and emitted airborne particles, for both microbial (n = 9) and inorganic (n = 15) constituents. When evaluating emissions and the consequent health outcomes, ventilation rates of specific exposure scenarios affect the concentrations of emitted particles. Thus, well-ventilated rooms may alleviate inhalation risks when the fill water in ultrasonic humidifiers contains microorganisms and soluble metals/minerals. Case reports (n = 3) possibly due to the inhalation of particles from ultrasonic humidifier include hypersensitivity pneumonitis in adults and a 6-month infant; the young infant exhibited nonreversible mild obstructive ventilator defect. In summary, related literature indicated correlation between fill water quality of ultrasonic humidifier and emitted particles in air quality, and inhalation of the emitted particles may cause undesirable health outcomes of impaired respiratory functions in adults and children.

Associations between home renovation and asthma, allergic rhinitis, and eczema among preschool children in Wuhan, China

To investigate the potential associations between household renovation and allergic diseases among preschool children in Wuhan, we conducted a large cross-sectional questionnaire survey among 9455 preschool children aged 3-6 years in Wuhan during November to December 2019. Data on demographics, health status, and home decoration conditions were analysed based on a questionnaire. Compared with tiles/stone/cement floor covering, the use of composite floor significantly increased the risk of diagnosed rhinitis and eczema among children (rhinitis: AOR, 95% CI: 1.36, 1.06-1.73; eczema: AOR, 95% CI: 1.47, 1.17-1.85). Household renovation had significant associations with diagnosed eczema (within 1 year before pregnancy: AOR, 95% CI: 1.34, 1.20-1.50; during pregnancy: AOR, 95% CI: 1.25, 1.08-1.44). This study suggests that use of artificial synthetic materials in home renovation during early childhood and pregnancy may be potential risk factors for childhood asthma, allergic rhinitis, and eczema.

Investigation of indoor and outdoor air quality in a university campus during COVID-19 lock down period

The pandemic of COVID-19 currently shadows the world; the whole earth has been on an unprecedented lockdown. Social distancing among people interrupted domestic and international air traffic, suspended industrial productions and economic activities, and had various far-reaching and undetermined implications on air quality. Improvement in air quality has been reported in many cities during the lockdown. On March 22, 2020, the Turkish government enforced strict lockdown measures to reduce coronavirus disease transmission. This lockdown had a significant impact on the movement of people within the country, which resulted in a major drop in worldwide commercial activities. During this period, university campuses were emptied due to the transition to distance education. In this study, various air pollutants sulfur dioxide (SO₂), nitrogen dioxide (NO₂), ozone (O₃), fine particulate matter (PM_2.5), total bacteria, and total fungi were measured in different indoor environments at Eskişehir Technical University Campus in Eskişehir, Turkey during COVID-19 lock down period. Also, to calculate the indoor and outdoor ratios (I/O) of the pollutants, simultaneous outdoor measurements were also carried out. The average indoor SO_2, NO_2, O_3, and PM_2.5 concentrations in different indoor environments ranged between 2.10 and 54.58, 1.36-30.89, 12.01-39.05, and 21-94 μg/m³, respectively. The total number of bacteria and fungi ranged between 21.83-514.15 and 13.10-83.36 CFU/m³, respectively. Our study intends to give a glimpse to quantify the impact of a pandemic on air quality in different indoor environments in a university campus in Eskişehir, Turkey and calls for follow-up studies. Indoor concentrations were evaluated together with outdoor concentrations. In general, it can be said that the calculated I/O ratios for SO₂, NO₂, O₃, bacteria, and fungi were less than 1 in most indoor environments.

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.

Tracing of Heavy Metals Embedded in Indoor Dust Particles from the Industrial City of Asaluyeh, South of Iran

Assessment of indoor air quality is especially important, since people spend substantial amounts of time indoors, either at home or at work. This study analyzes concentrations of selected heavy metals in 40 indoor dust samples obtained from houses in the highly-industrialized Asaluyeh city, south Iran in spring and summer seasons (20 samples each). Furthermore, the health risk due to exposure to indoor air pollution is investigated for both children and adults, in a city with several oil refineries and petrochemical industries. The chemical analysis revealed that in both seasons the concentrations of heavy metals followed the order of Cr > Ni > Pb > As > Co > Cd. A significant difference was observed in the concentrations of potential toxic elements (PTEs) such as Cr, As and Ni, since the mean (±stdev) summer levels were at 60.2 ± 9.1 mg kg−1, 5.6 ± 2.7 mg kg−1 and 16.4 ± 1.9 mg kg−1, respectively, while the concentrations were significantly lower in spring (17.6 ± 9.7 mg kg−1, 3.0 ± 1.7 mg kg−1 and 13.5 ± 2.4 mg kg−1 for Cr, As and Ni, respectively). Although the hazard index (HI) values, which denote the possibility of non-carcinogenic risk due to exposure to household heavy metals, were generally low for both children and adults (HI < 1), the carcinogenic risks of arsenic and chromium were found to be above the safe limit of 1 × 10−4 for children through the ingestion pathway, indicating a high cancer risk due to household dust in Asaluyeh, especially in summer.

Global Research Trends on Building Indoor Environmental Quality Modelling and Indexing Systems—A Scientometric Review

The purpose of this study is to provide a holistic review of two decades of research advancement in the indoor environmental quality modelling and indexing field (IEQMI) using bibliometric analysis methods. The explicit objectives of the present study are: (1) identifying researchers, institutions, countries (territories), and journals with the most influence in the IEQMI topic; (2) investigating the hot topics in the IEQMI field; and (3) thematically analysing the keyword evolution in the IEQMI field. A scientometric review was conducted using the bibliometric data of 456 IEQMI research articles published in the past two decades. VOSviewer software was employed for bibliometric analysis, and the SciMAT tool was used to investigate the keywords’ thematic evolution in three sub-periods (2004–2009; 2010–2015; 2016–2021). Results show that there is a continuous increment in the number of published papers in the field of IEQMI, and 60 out of 193 countries in the world have been involved in IEQMI studies. The IEQMI research mainly focuses on: (a) thermal comfort and energy efficiency; (b) occupant satisfaction and comfort; (c) IAQ and health issues; (d) methods and procedures. This field has undergone significant evolution. While ‘indoor environmental quality was initially the only theme in the first period’, ‘occupant satisfaction’, ‘buildings’, ‘impact’, ‘building information modelling’, and ‘health’ were added as the main thematic areas in the second period; ‘occupant behaviour’ and ‘energy’ were novel themes in IEQMI studies receiving much attention in the third period.

The cost-effectiveness of standalone HEPA filtration units for the prevention of airborne SARS CoV-2 transmission

OBJECTIVE

Airborne infection from aerosolized SARS-CoV-2 poses an economic challenge for businesses without existing heating, ventilation, and air conditioning (HVAC) systems. The Environmental Protection Agency notes that standalone units may be used in areas without existing HVAC systems, but the cost and effectiveness of standalone units has not been evaluated.

STUDY DESIGN

Cost-effectiveness analysis with Monte Carlo simulation and aerosol transmission modeling.

METHODS

We built a probabilistic decision-analytic model in a Monte Carlo simulation that examines aerosol transmission of SARS-CoV-2 in an indoor space. As a base case study, we built a model that simulated a poorly ventilated indoor 1000 square foot restaurant and the range of Covid-19 prevalence of actively infectious cases (best-case: 0.1%, base-case: 2%, and worst-case: 3%) and vaccination rates (best-case: 90%, base-case: 70%, and worst-case: 0%) in New York City. We evaluated the cost-effectiveness of improving ventilation rate to 12 air changes per hour (ACH), the equivalent of hospital-grade filtration systems used in emergency departments. We also provide a customizable online tool that allows the user to change model parameters.

RESULTS

All 3 scenarios resulted in a net cost-savings and infections averted. For the base-case scenario, improving ventilation to 12 ACH was associated with 54 [95% Credible Interval (CrI): 29-86] aerosol infections averted over 1 year, producing an estimated cost savings of $152,701 (95% CrI: $80,663, $249,501) and 1.35 (95% CrI: 0.72, 2.24) quality-adjusted life years (QALYs) gained.

CONCLUSIONS

It is cost-effective to improve indoor ventilation in small businesses in older buildings that lack HVAC systems during the pandemic.

A Review on Research and Development of Healthy Building in China

Healthy buildings are a deep-level development of green buildings, which can effectively help relieve stress and improve occupants’ physical and mental health. In addition, they are is likely to play an important role in preventing the spread of respiratory infectious diseases. Therefore, healthy buildings have attracted worldwide attention. This article reviews the research and development of healthy buildings in China. First, it briefly introduces the definition of healthy buildings, the key elements of evaluation standards, energy conservation measures and new technology applications for healthy buildings, and lessons learned from the global outbreak of SARS-CoV-2. Secondly, it presents the milestones of healthy building development and healthy building projects in China, and the benefits of healthy buildings were also discussed. Finally, the differences in the evaluation systems of healthy buildings between China and other countries were analyzed, the problems of the current policy system of healthy buildings in China were identified, and suggestions for future development were provided.

Latest Trends in Pollutant Accumulations at Threatening Levels in Energy-Efficient Residential Buildings with and without Mechanical Ventilation: A Review

Improving the energy efficiency of buildings is a major target in developed countries toward decreasing their energy consumption and CO₂ emissions. To meet this target, a large number of countries have established energy codes that require buildings to be airtight. While such a retrofitting approach has improved health outcomes in areas with heavy traffic, it has worsened the health outcomes in Nordic countries and increased the risk of lung cancer in areas with high levels of radon emissions. This review highlights the importance of adapting the characteristics of energy-efficient residential buildings to the location, age, and health of inhabitants to guarantee healthy indoor pollutant levels. The implementation of mechanical ventilation in new energy-efficient buildings has solved some of these problems; however, for others, a decrease in the level of outdoor pollutants was still required in order to achieve a good indoor air quality. A good balance between the air exchange rate and the air humidity level (adapted to the location) is key to ensuring that exposure to the various pollutants that accumulate inside energy-efficient buildings is low enough to avoid affecting inhabitants′ health. Evidence of the protective effect of mechanical ventilation should be sought in dwellings where natural ventilation allows pollutants to accumulate to threatening levels. More studies should be carried out in African and Asian countries, which, due to their rapid urbanization, use massive volumes of unproven/unrated building materials for fast-track construction, which are frequent sources of formaldehyde and VOC emissions.

Association between indoor ventilation frequency and cognitive function among community-dwelling older adults in China: results from the Chinese longitudinal healthy longevity survey

Backgrounds

Emerging evidence suggested that indoor air pollution caused long-term adverse effects on cognitive function among older adults who spend more than 85% of their time indoors. Although high indoor ventilation can mitigate the effect of indoor air pollution on cognition among the younger population, limited evidence revealed the association between indoor ventilation and cognition among older adults.

Methods

A total of 11,853 participants aged 65 and over (female, 54.5%; mean age, 83.6 years) were included from the 2017–2018 wave of the Chinese Longitudinal Healthy Longevity Survey (CLHLS). Indoor ventilation frequency was measured by the self-reported frequency of opening windows per week in each season. Cognitive function was evaluated by the Mini-Mental State Examination (MMSE). Multivariate Poisson regression with robust error variance was applied to assess the association between overall indoor ventilation frequency and cognitive function. We fitted in two adjusted models: Model 1 was adjusted for demographic; model 2 was further adjusted for lifestyle, socioeconomic status, health conditions, and environmental factors. The same models were also applied to measure the association between seasonal indoor ventilation frequency and cognitive function.

Results

Of 11,853 older adults, 3035 (25.6%) had cognitive impairment. A high overall indoor ventilation frequency (indoor ventilation frequency: 6–8) was significantly associated with a 9% lower likelihood of cognitive impairment than low overall indoor ventilation frequency (indoor ventilation frequency: 0–3) among Chinese older adults [Relative risk (RR): 0.91, 95% Confidential Interval (CI): 0.83–0.99] in the full adjusted model. In the subgroup analysis in four seasons, high and intermediate indoor ventilation frequency in winter were significantly associated with 8% (RR: 0.92; 95%CI: 0.86–0.99) and 16% (RR: 0.84; 95%CI: 0.78–0.90) lower probability of cognitive impairment than low indoor ventilation frequency in the fully adjusted model among Chinese older adults, respectively.

Conclusions

In this nationally representative cohort, a higher frequency of house ventilation by opening windows was significantly associated with a lower risk of cognitive impairment among Chinese older adults aged 65 and over. These results offered robust evidence for policymaking and health intervention to prevent older adults from cognitive impairment or dementia in developing regions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-022-02805-1.

Understanding teachers' experiences of ventilation in California K-12 classrooms and implications for supporting safe operation of schools in the wake of the COVID-19 pandemic

Classrooms are often under-ventilated, posing risks for airborne disease transmission as schools have reopened amidst the COVID-19 pandemic. While technical solutions to ensure adequate air exchange are crucial, this research focuses on teachers' perceptions and practices that may also have important implications for achieving a safe classroom environment. We report on a (pre-pandemic) survey of 84 teachers across 11 California schools, exploring their perceptions of environmental quality in relation to monitored indoor environmental quality (IEQ) data from their classrooms. Teachers were not educated regarding mechanical ventilation. Errors in HVAC system installation and programming contributed to misunderstandings (because mechanical ventilation was often not performing as it should) and even occasionally made it possible for teachers to turn off the HVAC fan (to reduce noise). Teachers did not accurately perceive (in)sufficient ventilation; in fact, those in classrooms with poorer ventilation were more satisfied with IEQ, likely due to more temperature fluctuations when ventilation rates were higher combined with occupants' tendency to conflate perceptions of air quality and temperature. We conclude that classroom CO₂  monitoring and teacher education are vital to ensure that teachers feel safe in the classroom and empowered to protect the health of themselves and their students.

A review of occupancy-based building energy and IEQ controls and its future post-COVID

Occupancy schedules and density can have a substantial influence on building plug, lighting, and air conditioning energy usage. In recent years, the study related to occupancy and its impact on building energy consumption has gained momentum and is also promoted by ASHRAE as it has created a multi-disciplinary group to encourage a comprehensive study of occupant behaviour in buildings. Past studies suggest that building systems do not consume the same energy and provide similar Indoor Environmental Quality (IEQ) to their designed specifications due to inaccurate assumptions of occupants and their behaviour. Supplying ASHRAE 62.1 specified minimum required ventilation based on accurate occupancy may lead to significant air-conditioning energy savings. However, the same strategy is not suitable in the current time since minimum required ventilation may not be sufficient to mitigate the SARS-CoV-2 virus spread in confined spaces. High-temperature cooling augmented with elevated air movement across an acceptable range of velocity can maintain the health and comfort of occupants by providing higher ventilation and without an energy penalty. The analysis of the literature highlights strengths, weaknesses, and key observations about the existing occupancy monitoring and occupancy-based building system control methods to help in the direction of future occupancy-based research.

PCA-Based Identification of Built Environment Factors Reducing PM2.5 Pollution in Neighborhoods of Five Chinese Megacities

Air pollution, especially PM2.5 pollution, still seriously endangers the health of urban residents in China. The built environment is an important factor affecting PM2.5; however, the key factors remain unclear. Based on 37 neighborhoods located in five Chinese megacities, three relative indicators (the range, duration, and rate of change in PM2.5 concentration) at four pollution levels were calculated as dependent variables to exclude the background levels of PM2.5 in different cities. Nineteen built environment factors extracted from green space and gray space and three meteorological factors were used as independent variables. Principal component analysis was adopted to reveal the relationship between built environment factors, meteorological factors, and PM2.5. Accordingly, 24 models were built using 32 training neighborhood samples. The results showed that the adj_R2 of most models was between 0.6 and 0.8, and the highest adj_R2 was 0.813. Four principal factors were the most important factors that significantly affected the growth and reduction of PM2.5, reflecting the differences in green and gray spaces, building height and its differences, relative humidity, openness, and other characteristics of the neighborhood. Furthermore, the relative error was used to test the error of the predicted values of five verification neighborhood samples, finding that these models had a high fitting degree and can better predict the growth and reduction of PM2.5 based on these built environment factors.

Study on the Effect of an Intermittent Ventilation Strategy on Controlling Formaldehyde Concentrations in Office Rooms

Material emission and ventilation are two aspects influencing indoor air quality. In this study, a model predictive control (MPC) strategy is proposed for intermittent ventilation system in office buildings, to achieve a healthy indoor environment. The strategy is based on a dynamic model for predicting emissions of volatile organic compounds (VOCs) from materials. The key parameters of formaldehyde from panel furniture in the model are obtained by an improved C-history method and large-scale chamber experiments. The effectiveness of the determined key parameters is validated, which are then used to predict the formaldehyde concentration variation and the pre-ventilation time in a typical office room. In addition, the influence of some main factors (i.e., vacant time, loading ratio, air change rate) on the pre-ventilation time is analyzed. Results indicate that the pre-ventilation time of the intermittent ventilation system ranges from several minutes to several hours. The pre-ventilation time decreases exponentially with the increase in the vacant time, the air change rate, and with the decrease in the loading ratio. When the loading ratio of the furniture is 0.30 m2/m3 and the vacant time is 100 days, the required pre-ventilation time approaches zero. Results further reveal that an air change rate of 2 h−1 is the most effective means for rapid removal of indoor formaldehyde for the cases studied. The proposed strategy should be helpful for achieving effective indoor pollution control.

Subjective indoor air quality and thermal comfort among adults in relation to inspected and measured indoor environment factors in single-family houses in Sweden-the BETSI study

Totally 1160 adults living in single-family houses in Sweden participated in a questionnaire survey on subjective indoor air quality (SIAQ). Inspectors investigated the dwellings and performed home measurements (mean indoor temperature 21.4 °C, mean indoor air humidity 34.2%, mean indoor air exchange rate 0.36 ac/h and mean moisture load indoor 1.7 g/m³). Totally 15.5% perceived draught, 28.0% perceived too high room temperature, 42.4% unstable room temperature, 36.8% too low room temperature, 19.6% stuffy air, 19.8% dry air and 29.9% dust or dirt. Measured room temperature was related to perception of room temperature. Higher relative air humidity was related to perceived unstable room temperature (OR = 1.70) and too low room temperature (OR = 1.96). Higher absolute air humidity was related to too high room temperature (OR = 1.21), unstable room temperature (OR = 1.34) and too low room temperature (OR = 1.35). Higher measured relative humidity, absolute air humidity and moisture load were all associated with stuffy air and unpleasant odor (OR = 1.45-1.97). Higher air exchange rate was related to less perceived unstable room temperature (OR = 0.93). Higher U value was related to draught (OR = 1.17), too low room temperature (OR = 1.09), unpleasant odor (OR = 1.12) and dust and dirt (OR = 1.07). New concrete slab foundation was related to less stuffy air (OR = 0.39) (vs. basement). Damp foundation was associated with more stuffy air (OR = 1.44) and unpleasant odor (OR = 1.61). Window pane condensation was related to stuffy air (OR = 1.88). Moldy odor reported by inspector was related to stuffy air (OR = 1.73). Observed mold in the attic was associated with more stuffy air and unpleasant odor. In conclusion, complaints of room temperature can indicate poor thermal environment. Higher air exchange rate can create a more stable thermal sensation. Excess indoor humidity, lower degree of thermal insulation, presence of window pane condensation and indoor dampness/mold can impair SIAQ. Higher ventilation and concrete slab foundation with underlying thermal insulation can improve SIAQ.

Control of airborne infectious disease in buildings: Evidence and research priorities

The evolution of SARS-CoV-2 virus has resulted in variants likely to be more readily transmitted through respiratory aerosols, underscoring the increased potential for indoor environmental controls to mitigate risk. Use of tight-fitting face masks to trap infectious aerosol in exhaled breath and reduce inhalation exposure to contaminated air is of critical importance for disease control. Administrative controls including the regulation of occupancy and interpersonal spacing are also important, while presenting social and economic challenges. Indoor engineering controls including ventilation, exhaust, air flow control, filtration, and disinfection by germicidal ultraviolet irradiation can reduce reliance on stringent occupancy restrictions. However, the effects of controls-individually and in combination-on reducing infectious aerosol transfer indoors remain to be clearly characterized to the extent needed to support widespread implementation by building operators. We review aerobiologic and epidemiologic evidence of indoor environmental controls against transmission and present a quantitative aerosol transfer scenario illustrating relative differences in exposure at close-interactive, room, and building scales. We identify an overarching need for investment to implement building controls and evaluate their effectiveness on infection in well-characterized and real-world settings, supported by specific, methodological advances. Improved understanding of engineering control effectiveness guides implementation at scale while considering occupant comfort, operational challenges, and energy costs.

Housing and Health: Here We Go Again

Housing is one of the major determinants of human health and the current COVID-19 pandemic has highlighted its relevance. The authors summarize the main issues, including dimensional standards, indoor air quality, safety, accessibility, neighborhoods, and area characteristics. The authors propose an operating scheme in order to implement actions to improve residential wellbeing on a local, national, and international level.

The effects of warmth and CO2 concentration, with and without bioeffluents, on the emission of CO2 by occupants and physiological responses

The emission rate of carbon dioxide (CO₂ ) depends on many factors but mainly on the activity level (metabolic rate) of occupants. In this study, we examined two other factors that may influence the CO₂ emission rate, namely the background CO₂ concentration and the indoor temperature. Six male volunteers sat one by one in a 1.7 m³ chamber for 2.5 h and performed light office-type work under five different conditions with two temperature levels (23 vs. 28°C) and three background concentrations of CO₂ (800 vs. 1400 vs. 3000 ppm). Background CO₂ levels were increased either by dosing CO₂ from a cylinder or by reducing the outdoor air supply rate. Physiological responses to warmth, added CO₂ , and bioeffluents were monitored. The rate of CO₂ emission was estimated using a mass-balance equation. The results indicate a higher CO₂ emission rate at the higher temperature, at which the subjects were warm, and a lower emission rate in all conditions in which the background CO₂ concentration increased. Physiological measurements partially explained the present results but more measurements are needed.

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.

Assessment of Personal Relaxation in Indoor-Air Environments: Study in Real Full-Scale Laboratory Houses

The relationship between chemical concentrations in indoor air and the human sense of comfort and relaxation have been reported. We investigated the effect of the sum of volatile organic compounds (ΣVOCs; sum of 79 VOCs) on the level of relaxation in two laboratory houses with almost identical interior and exterior appearances. The electroencephalogram (EEG) was monitored to evaluate the degree of personal relaxation objectively. The experiments were conducted in laboratory houses (LH) A and B with lower and higher levels of ΣVOCs, respectively. A total of 168 healthy volunteers participated, who each performed the task for 20 min, followed by a 10-min break, and EEG was measured during the break. Simultaneously as subjective evaluations, the participants were asked to fill a questionnaire regarding the intensity of odor and preference for the air quality in each LH. The subjective evaluation showed a significant association between ΣVOCs and participants’ relaxation (OR: 2.86, 95%CI: 1.24–6.61), and the objective evaluation indicated that the participants were more relaxed in the LH with lower levels of ΣVOCs than that with higher levels (OR: 3.03, 95%CI: 1.23–7.50). Therefore, the reduction of ΣVOCs and odors in indoor air would have an effect, which is the promotion of relaxation.

The short-term effect of residential home energy retrofits on indoor air quality and microbial exposure: A case-control study

Weatherization of residential homes is a widespread procedure to retrofit older homes to improve the energy efficiency by reducing building leakage. Several studies have evaluated the effect of weatherization on indoor pollutants, such as formaldehyde, radon, and indoor particulates, but few studies have evaluated the effect of weatherization on indoor microbial exposure. Here, we monitored indoor pollutants and bacterial communities during reductions in building leakage for weatherized single-family residential homes in New York State and compared the data to non-weatherized homes. Nine weatherized and eleven non-weatherized single-family homes in Tompkins County, New York were sampled twice: before and after the weatherization procedures for case homes, and at least 3 months apart for control homes that were not weatherized. We found that weatherization efforts led to a significant increase in radon levels, a shift in indoor microbial community, and a warmer and less humid indoor environment. In addition, we found that changes in indoor airborne bacterial load after weatherization were more sensitive to shifts in season, whereas indoor radon levels were more sensitive to ventilation rates.

Effects of mechanical ventilation on indoor air quality and occupant health status in energy-efficient homes: A longitudinal field study

Despite the growing interest in energy-efficient homes (EEHs), there is still a lack of evidence regarding whether the mechanical ventilation system of an EEH positively or negatively impacts indoor air quality (IAQ) and the health and wellbeing of occupants. This study aimed to evaluate the IAQ level and daily health symptoms of adults and children living in EEHs compared to conventional buildings over the course of one year. A two-way mixed analysis of variance was conducted to compare the level of IAQ between the two housing types. A binomial generalized linear mixed model (GLMM) and generalized additive mixed model was developed to investigate the association between IAQ and daily risks of symptoms. Differences in the daily prevalence of symptoms between the two housing types were assessed using a Poisson GLMM model. Overall, the indoor concentrations of particulate matter (PM₁₀ and PM_2.5), carbon dioxide (CO₂), and volatile organic compounds (VOCs) were lower in EEH after controlling for seasonality. The indoor temperature and relative humidity level were relatively constant in the EEH. We also found that an increased level of indoor air quality parameters, particularly CO_2, which is closely related to the indoor ventilation rate, was associated with the daily risk of eye fatigue, allergic rhinitis, and atopic dermatitis symptoms. Considering that EEH effectively reduced indoor air pollutants and IAQ improvement was associated with a reduction in the risk of individual symptoms, the IAQ improvement of EEH may have positively impacted occupants' health. Symptoms such as eye fatigue and skin dryness, which have been reported in previous studies as potential side effects of mechanical ventilation, were reported in this study; however, they were not found to be statistically significantly different from those reported in the conventional building.

The home environment in a nationwide sample of multi-family buildings in Sweden: associations with ocular, nasal, throat and dermal symptoms, headache, and fatigue among adults

Risk factors at home for ocular, nasal, throat and dermal symptoms, headache, and fatigue were studied in a nationwide questionnaire survey in Sweden, the BETSI study in 2006. Totally, 5775 adults from a stratified random sample of multi-family buildings participated. Associations between home environment factors and weekly symptoms were analyzed by multi-level logistic regression. In total, 8.3% had ocular symptoms; 11.9% nasal symptoms; 7.1% throat symptoms; 11.9% dermal symptoms; 8.5% headache and 23.1% fatigue. Subjects in colder climate zones had more mucosal and throat symptoms but less fatigue and ocular symptoms. Rented apartments had poorer indoor environment than self-owned apartments. Those living in buildings constructed from 1961 to 1985 had most symptoms. Building dampness, mold and mold odor were risk factors, especially headache and ocular symptoms. Lack of mechanical ventilation system was another risk factor, especially for headache. Environmental tobacco smoke (ETS), electric radiators, and crowdedness were other risk factors. Oiled wooden floors, recent indoor painting, and new floor materials were negatively associated with symptoms. In conclusion, building dampness, mold, poor ventilation conditions, crowdedness, ETS, and emissions from electric radiators in apartments in Sweden can increase the risk of ocular, nasal, throat and dermal symptoms, headache, and fatigue.

Field-based longitudinal study design for measuring the association between indoor air quality and occupant health status in residential buildings

There has been a growing interest in the association between indoor air quality (IAQ) with an increase in the time spent at home. However, there is still a lack of evidence on the impact of IAQ on occupants' health and well-being in the long term. This study aimed to develop a field-based longitudinal study design to evaluate the IAQ level and daily symptoms of adults and children living in different types of buildings over one year. We proposed vital principles to be considered when recruiting the study participants so that potential confounders, such as age, underlying diseases, and the geographic area would be either removed in advance or matched between different building types. We suggested collecting exposure and outcome data in three categories: lifestyle and housing environment, IAQ measurement, and occupants' health. We presented web-based survey tools for collecting housing and health data, and the frequency of data collection varied from weekly to six-month intervals. We developed two different models using a generalized mixed model for modeling the association between housing environment, IAQ, and human health. The current study design could be applied for future studies on the association between built environment and health, regardless of the type of buildings.•

A real-time indoor air quality monitor was used to monitor indoor air parameters every 5 mins over one year.

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A simple web-based survey tool was developed to collect data for occupants' daily symptoms in the long term.

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A binomial generalized linear mixed model and a Poisson generalized linear mixed model was developed to evaluate the association between indoor air parameters, and building types and daily symptoms.

Assessing ventilation strategies in a school with observed indoor air problems

Purpose

Poor indoor air quality in schools is a worldwide challenge that poses health risks to pupils and teachers. A possible response to this problem is to modify ventilation. Therefore, the purpose of this paper is to pilot a process of generating alternatives for ventilation redesign, in an early project phase, for a school to be refurbished. Here, severe problems in indoor air quality have been found in the school.

Design/methodology/approach

Ventilation redesign is investigated in a case study of a school, in which four alternative ventilation strategies are generated and evaluated. The analysis is mainly based on the data gathered from project meetings, site visits and the documents provided by ventilation and condition assessment consultants.

Findings

Four potential strategies to redesign ventilation in the case school are provided for decision-making in refurbishment in the early project phase. Moreover, the research presents several features to be considered when planning the ventilation strategy of an existing school, including the risk of alterations in air pressure through structures; the target number of pupils in classrooms; implementing and operating costs; and the size of the space that ventilation equipment requires.

Research limitations/implications

As this study focusses on the early project phase, it provides viewpoints to assist decision-making, but the final decision requires still more accurate calculations and simulations.

Originality/value

This study demonstrates the decision-making process of ventilation redesign of a school with indoor air problems and provides a set of features to be considered. Hence, it may be beneficial for building owners and municipal authorities who are engaged in planning a refurbishment of an existing building.

Evaluating Indoor Air Chemical Diversity, Indoor-to-Outdoor Emissions, and Surface Reservoirs Using High-Resolution Mass Spectrometry

Detailed offline speciation of gas- and particle-phase organic compounds was conducted using gas/liquid chromatography with traditional and high-resolution mass spectrometers in a hybrid targeted/nontargeted analysis. Observations were focused on an unoccupied home and were compared to two other indoor sites. Observed gas-phase organic compounds span the volatile to semivolatile range, while functionalized organic aerosols extend from intermediate volatility to ultra-low volatility, including a mix of oxygen, nitrogen, and sulfur-containing species. Total gas-phase abundances of hydrocarbon and oxygenated gas-phase complex mixtures were elevated indoors and strongly correlated in the unoccupied home. While gas-phase concentrations of individual compounds generally decreased slightly with greater ventilation, their elevated ratios relative to controlled emissions of tracer species suggest that the dilution of gas-phase concentrations increases off-gassing from surfaces and other indoor reservoirs, with volatility-dependent responses to dynamically changing environmental factors. Indoor-outdoor emissions of gas-phase intermediate-volatility/semivolatile organic hydrocarbons from the unoccupied home averaged 6-11 mg h^-1, doubling with ventilation. While the largest single-compound emissions observed were furfural (61-275 mg h^-1) and acetic acid, observations spanned a wide range of individual volatile chemical products (e.g., terpenoids, glycol ethers, phthalates, other oxygenates), highlighting the abundance of long-lived reservoirs resulting from prior indoor use or materials, and their gradual transport outdoors.

Assessment of personal exposure to infectious contaminant under the effect of indoor air stability

The objective of this study is to understand the effect of indoor air stability on personal exposure to infectious contaminant in the breathing zone. Numerical simulations are carried out in a test chamber with a source of infectious contaminant and a manikin (Manikin A). To give a good visual illustration of the breathing zone, the contaminant source is visualized by the mouth of another manikin. Manikin A is regarded as a vulnerable individual to infectious contaminant. Exposure index and exposure intensity are used as indicators of the exposure level in the breathing zone. The results show that in the stable condition, the infectious contaminant proceeds straightly towards the breathing zone of the vulnerable individual, leading to a relatively high exposure level. In the unstable condition, the indoor air experiences a strong mixing due to the heat exchange between the hot bottom air and the cool top air, so the infectious contaminant disperses effectively from the breathing zone. The unstable air can greatly reduce personal exposure to the infectious contaminant in the breathing zone. This study demonstrates the importance of indoor air stability on personal exposure in the indoor environment and provides a new direction for future study of personal exposure reduction in the indoor environment.

The climate and health benefits from intensive building energy efficiency improvements

Intensive building energy efficiency improvements can reduce emissions from energy use, improving outdoor air quality and human health, but may also affect ventilation and indoor air quality. This study examines the effects of highly ambitious, yet feasible, building energy efficiency upgrades in the United States. Our energy efficiency scenarios, derived from the literature, lead to a 6 to 11% reduction in carbon dioxide emissions and 18 to 25% reductions in particulate matter (PM2.5) emissions in 2050. These reductions are complementary with a carbon pricing policy on electricity. However, our results also point to the importance of mitigating indoor PM2.5 emissions, improving PM2.5 filtration, and evaluating ventilation-related policies. Even with no further ventilation improvements, we estimate that intensive energy efficiency scenarios could prevent 1800 to 3600 premature deaths per year across the United States in 2050. With further investments in indoor air quality, this can rise to 2900 to 5100.

COVID-19 virus released from larynx might cause a higher exposure dose in indoor environment

COVID-19 virus can replicate in the infected individual's larynx independently, which is different from other viruses that replicate in lungs only, e.g. SARS. It might contribute to the fast spread of COVID-19. However, there are few scientific reports about quantitative comparison of COVID-19 exposure dose (inhalation dose and adhesion dose) for the susceptible individual when the viruses were released from the larynx or lungs. In this paper, a typical numerical model was built based on a breathing human model with real respiratory tract. By using a computational fluid dynamics (CFD) method, two kinds of virus released sites in the infected individual's respiratory tract (larynx, lungs), seven kinds of particle sizes between 1 and 50 μm, three kinds of expiratory flow rates: calm (10 L/min), moderate (30 L/min) and intense (90 L/min) were used to compare the particle deposition proportion and escape proportion. The inhalation dose and the adhesion dose of the susceptible individual were quantified. The results showed that COVID-19 virus-containing droplets and aerosols might be released into the environment at higher proportions (39.1%-44.2%) than viruses that replicate in lungs only (15.3%-37.1%). The exposure doses (inhalation dose and adhesion dose) of the susceptible individual in different situations were discussed. The susceptible individual suffered a higher exposure dose when the viruses were released from the larynx rather than lungs (the difference for 1 μm particles was 1.2-2.2 times). This study provides a possible explanation for the higher transmission risk of COVID-19 virus compared to other viruses and some control advice of COVID-19 in typical indoor environments were also discussed.

Comparative Modelling Analysis of Air Pollutants, PM2.5 and Energy Efficiency Using Three Ventilation Strategies in a High-Rise Building: A Case Study in Suzhou, China

This study investigated the ventilation efficiency and energy performance of three ventilation strategies—an all-air system (AAS), a radiant panel system with a displacement ventilation system (DPS), and a radiant panel system with a decentralized ventilation system (DVS). The research analyzed the indoor air quality (IAQ) in a high-rise building based on the building’s height, the air handling unit (AHU) location, air infiltration rate, outdoor air pollution rate, seasonal change, and air filter efficiency. The results indicated that the AAS had the best performance in terms of IAQ in the high-rise building in winter; however, the AAS also had the highest annual energy demand. For the same conditions, the DVS consumed less energy but had the worst performance in maintaining a satisfactory IAQ. Considering energy consumption, it is worth developing the DVS further to improve ventilation performance. By applying a double-filter system on the lower floors in a high-rise building, the DVS’s ventilation performance was dramatically improved while at the same time consuming less energy than the original DPS and AAS. The application of DVS can also minimize the negative effect of the infiltration rate on indoor air quality (IAQ) in a building, which means that the DVS can better maintain IAQ within a healthy range for a more extended period. Moreover, it was found that the DVS still had a substantial potential for saving energy during the season when the outdoor air was relatively clean. Hence, it is highly recommended that the DVS is used in high-rise buildings.

The Comfort Map—A Possible Tool for Increasing Personal Comfort in Office Workplaces

Previous studies have shown that indoor environmental quality (IEQ) parameters may have a considerable effect on office employees’ comfort, health and performance. Therefore, we initiated a research program to help occupants identify IEQ parameters they perceive as risk factors for their health in an office and enhance their comfort levels in an office environment. Since we assumed that office employees might have different indoor environmental quality expectations related to their work area and that these differences could be measured, our objective was to develop an office ‘comfort map’ based on occupants’ individual IEQ preferences. Thus, the goal of the comfort map would be to help tailor office spaces to their occupants’ health and comfort expectations. The comfort survey was developed to assess the comfort-related opinions of the occupants, based on IEQ parameters (visual comfort, acoustic comfort, air quality and thermal comfort) of a chosen open-plan office building. The survey also assessed the degree to which the given IEQ parameter was considered a health risk factor by occupants or caused a negative comfort sensation for them. The survey was filled in by 216 occupants. The answers were then analyzed with the help of a frequency table depicting relative frequency. The measurements of IEQ parameters took place in an open-plan office in the chosen office building (a Hungarian subsidiary’s office building belonging to an international company in Budapest). The occupants had different opinions regarding the perceived effects of the IEQ parameters on their health and comfort. Almost two-thirds of the respondents (64.8%) were dissatisfied with the adjustability of the noises and sounds IEQ parameter at their workstation. Furthermore, half of the respondents (50.1%) were dissatisfied with the adjustability of ventilation. Most of the occupants (45.8%) considered noises and sounds as the IEQ parameter that had a negative effect on their health. There were also IEQ differences between different areas of the office space. Based on these results, a comfort map was developed for the office. The comfort map contains information about the IEQ characteristics of each workstation by depicting the thermal comfort, carbon dioxide, visual comfort and acoustic comfort characteristics of a given workstation on a relative scale. Based on the thermal, air, acoustic, and lighting differences between the workstations, occupants can select their preferred workstations when a desk-sharing system works. Although still in its pilot phase, the comfort map could increase the chances for office employees to find the workstation best suited to their IEQ expectations. This could improve occupants’ overall comfort level, which could in turn enhance occupants’ productivity and mental as well as physical health.

Work Exposure to VOC in Storage Areas of Retail Stores

Poor indoor air quality (IAQ) has been linked to airway disease and early deaths. The ESQUISSE study of IAQ conducted by the French Research and Safety Institute (INRS), characterized the concentrations of various volatile organic compounds (VOCs) in 10 retail stores and storage areas. The IAQ was generally better in sales areas than storage areas, which are more often unventilated and overloaded with new products. For example, in clothing stores, formaldehyde concentrations between 29.0 and 45.0 µg m-3 were measured in non-ventilated storage areas located in the basement; in sales areas, concentrations did not exceed 10.2 µg m-3. Similarly, total VOC (TVOC) concentrations in the two main storage areas were 1153 and 1223 µg m-3 toluene equivalent, whereas they were less than 77.0 µg m-3 toluene equivalent in all sales areas. Many employees work in these high-exposure areas either temporarily or for the entire day, unpacking boxes, placing products on shelves, or collecting products. Reporting primarily on formaldehyde, toluene, or TVOC concentrations, this article shows, in addition to the distinction between sales and storage areas, how an unpacking task can affect an employee's exposure, and an example of the impact of ambient temperature on VOC concentrations. The results presented clearly highlight the issue of occupational exposure of workers in storage areas.

Indoor transmission of SARS-CoV-2

It is essential to understand where and how severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is transmitted. Case reports were extracted from the local Municipal Health Commissions of 320 prefectural municipalities in China (not including Hubei Province). We identified all outbreaks involving three or more cases and reviewed the major characteristics of the enclosed spaces in which the outbreaks were reported and their associated indoor environmental aspects. Three hundred and eighteen outbreaks with three or more cases were identified, comprising a total of 1245 confirmed cases in 120 prefectural cities. Among the identified outbreaks, 53.8% involved three cases, 26.4% involved four cases, and only 1.6% involved ten or more cases. Home-based outbreaks were the dominant category (254 of 318 outbreaks; 79.9%), followed by transport-based outbreaks (108; 34.0%), and many outbreaks occurred in more than one category of venue. All identified outbreaks of three or more cases occurred in indoor environments, which confirm that sharing indoor spaces with one or more infected persons is a major SARS-CoV-2 infection risk.

Indoor transmission of SARS-CoV-2

It is essential to understand where and how severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is transmitted. Case reports were extracted from the local Municipal Health Commissions of 320 prefectural municipalities in China (not including Hubei Province). We identified all outbreaks involving three or more cases and reviewed the major characteristics of the enclosed spaces in which the outbreaks were reported and their associated indoor environmental aspects. Three hundred and eighteen outbreaks with three or more cases were identified, comprising a total of 1245 confirmed cases in 120 prefectural cities. Among the identified outbreaks, 53.8% involved three cases, 26.4% involved four cases, and only 1.6% involved ten or more cases. Home-based outbreaks were the dominant category (254 of 318 outbreaks; 79.9%), followed by transport-based outbreaks (108; 34.0%), and many outbreaks occurred in more than one category of venue. All identified outbreaks of three or more cases occurred in indoor environments, which confirm that sharing indoor spaces with one or more infected persons is a major SARS-CoV-2 infection risk.

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.