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Gun ranges in the United States are underinvestigated regarding indoor air quality (IAQ) and energy efficiency. Navy Environmental Health Center (NEHC), National Guard Bureau (NGB), and Air Force Civil Engineer Support Agency (AFCESA) recommend using 100% outdoor air, but this measure will cause prohibitive energy costs since indoor gun ranges must maintain a low air velocity ranging from 0.25 to 0.36 m/s and a supply temperature close to the range target temperature. Hence, typical commercial firing ranges use a fixed outdoor air ratio (OAR) ranging from 25% to 30% together with high-efficiency particulate air filtration to save energy. This OAR is arbitrary and not supported by any standards or guidelines. To obtain reliable control of contaminant levels and better energy efficiency, we propose a model-based demand control ventilation feedback control strategy in which carbon monoxide is monitored and controlled as a proper IAQ indicator around the clock. Our 52-day field study demonstrates that our demand control ventilation control strategy can ensure proper IAQ, reduce the OAR from 30% to as low as 2.5%, and cut up to 85% cooling load and 70% heating load introduced by ventilation. Indoor gun ranges in the United States often struggle with keeping the air clean and energy costs down. Existing recommendations suggest using a lot of outdoor air for ventilation, but this can be expensive because gun ranges need to maintain specific air conditions. Most gun ranges use a fixed amount of outdoor air and special filters to save energy, even though there are no clear guidelines for this. To tackle these issues, we have come up with a smart ventilation system. It constantly checks the air for carbon monoxide, a sign of bad air quality. Our 52-day study showed that this system works considerably well. It keeps the air clean, reduces the need for outdoor air substantially, and cuts down on heating and cooling costs. This means that indoor gun ranges can have clean air and save energy at the same time. It is a practical and efficient solution for making indoor shooting ranges safer and more cost-effective. [ABSTRACT FROM AUTHOR]

Future climate change can cause more days with poor air quality. This could trigger more alerts telling people to stay inside to protect themselves, with potential consequences for health and health equity. Here, we study the change in US air quality alerts over this century due to fine particulate matter (PM2.5), who they may affect, and how they may respond. We find air quality alerts increase by over 1 mo per year in the eastern United States by 2100 and quadruple on average. They predominantly affect areas with high Black populations and leakier homes, exacerbating existing inequalities and impacting those less able to adapt. Reducing emissions can offer significant annual health benefits ($5,400 per person) by mitigating the effect of climate change on air pollution and its associated risks of early death. Relying on people to adapt, instead, would require them to stay inside, with doors and windows closed, for an extra 142 d per year, at an average cost of $11,000 per person. It appears likelier, however, that people will achieve minimal protection without policy to increase adaptation rates. Boosting adaptation can offer net benefits, even alongside deep emission cuts. New adaptation policies could, for example: reduce adaptation costs; reduce infiltration and improve indoor air quality; increase awareness of alerts and adaptation; and provide measures for those working or living outdoors. Reducing emissions, conversely, lowers everyone's need to adapt, and protects those who cannot adapt. Equitably protecting human health from air pollution under climate change requires both mitigation and adaptation. [ABSTRACT FROM AUTHOR]

Wildfire activity is increasing in parts of the world where extreme drought and warming temperatures contribute to fireprone conditions, including the western United States. The elderly are among the most vulnerable, and those in long‐term care with preexisting conditions have added risk for adverse health outcomes from wildfire smoke exposure. In this study, we report continuous co‐located indoor and outdoor fine particulate matter (PM2.5) measurements at four skilled nursing facilities in the western United States. Throughout the year 2020, over 8000 h of data were collected, which amounted to approximately 300 days of indoor and outdoor sampling at each facility. The highest indoor 24 h average PM2.5 recorded at each facility was 43.6 µg/m3, 103.2 µg/m3, 35.4 µg/m3, and 202.5 µg/m3, and these peaks occurred during the wildfire season. The indoor‐to‐outdoor PM2.5 ratio and calculated infiltration efficiencies indicated high variation in the impact of wildfire events on Indoor Air Quality between the four facilities. Notably, infiltration efficiency ranged from 0.22 to 0.76 across the four facilities. We propose that this variability is evidence that PM2.5 infiltration may be impacted by modifiable building characteristics and human behavioral factors, and this should be addressed in future studies. [ABSTRACT FROM AUTHOR]

Heating and cooling requirement differences across climates not only have carbon emissions and energy efficiency implications but also impact indoor air quality (IAQ) and health. Energy and IAQ building simulation models help understand tradeoffs or co‐benefits, but these have not been applied to evaluate climate zone or multi‐family home differences. We modeled a four‐story multi‐family home in six U.S. climate zones and quantified energy, IAQ, and health outcomes with EnergyPlus, CONTAM, and a pediatric asthma systems science model. Pollutant sources included cooking and ambient. Outputs were daily PM2.5 and NO2 indoor concentrations, infiltration, energy for heating and cooling, and asthma exacerbations, which were compared across climate zones, apartment units, and resident behaviors. Daily ambient‐sourced PM2.5 decreased and cooking‐sourced PM2.5 increased with higher ambient temperatures. Infiltration air changes per hour were higher on the first versus the fourth floor and in colder climates. Window opening during cooking led to decreases in total pollutant concentrations (11%–18% for PM2.5 and 9%–15% for NO2), 3%–4% decreases in asthma exacerbations within climate zones, and minimal impacts on cooling, but led to increased heating demand (4%–8%). Our results demonstrate the influence of meteorology, multi‐family building characteristics, and resident behavior on IAQ, energy, and health, focused on multi‐zone methodology. [ABSTRACT FROM AUTHOR]

Indoor air quality is critical for human health, and as such, it must be continuously improved. As a result, it is critical to identify the factors influencing indoor air quality. In this context, the purpose of this study is to investigate the factors influencing indoor air quality and to conduct a bibliometric analysis of the studies on the subject. The method of bibliometric analysis was used to examine academic publications on indoor air quality published between 1975 and 2020. A total of 2398 academic studies from the Web of Science database were examined. According to the findings of the analyses, academic research has primarily been conducted in the fields of construction technology and environmental sciences, public environmental occupational health, and environmental engineering. Since 2010, there has been a significant increase in the number of publications. The year with the most publications was 2017, and especially after 2010, publications have been cited more and more. One-fourth of the publications were produced solely in the United States. Hong Kong Polytechnic University and Denmark Technical University had the most publications. It has been determined that ventilation and air flow rate are the most heavily researched factors affecting indoor air quality. On the other hand, a substantial amount of research has been conducted to investigate the effects of pollutants. Furthermore, publications on temperature, humidity, bacteria, and thermal comfort were discovered. There have been studies on indoor air quality in residential buildings, houses, schools, and hospitals. [ABSTRACT FROM AUTHOR]

Background/aims: Wildfire air pollution is a growing public health concern as wildfires increase in size, intensity, and duration in the United States. The public is often encouraged to stay indoors during wildfire smoke events to reduce exposure. However, there is limited information on how much wildfire smoke infiltrates indoors at residences and what household/behavioral characteristics contribute to higher infiltration. We assessed fine particulate matter (PM 2.5 ) infiltration into Western Montana residences during wildfire season., Methods: We measured continuous outdoor and indoor PM 2.5 concentrations from July-October 2022 at 20 residences in Western Montana during wildfire season using low-cost PM 2.5 sensors. We used paired outdoor/indoor PM 2.5 data from each household to calculate infiltration efficiency (F inf ; range 0-1; higher values indicate more outdoor PM 2.5 infiltration to the indoor environment) using previously validated methods. Analyses were conducted for all households combined and for various household subgroups., Results: Median (25th percentile, 75th percentile) daily outdoor PM 2.5 at the households was 3.7 μg/m 3 (2.1, 7.1) during the entire study period and 29.0 μg/m 3 (19.0, 49.4) during a 2-week period in September impacted by wildfire smoke. Median daily indoor PM 2.5 at the households was 2.5 μg/m 3 (1.3, 5.5) overall and 10.4 μg/m 3 (5.6, 21.0) during the wildfire period. Overall F inf was 0.34 (95 % Confidence Interval [95%CI]: 0.33, 0.35) with lower values during the wildfire period (0.32; 95%CI: 0.28, 0.36) versus non-wildfire period (0.39; 95%CI: 0.37, 0.42). Indoor PM 2.5 concentrations and F inf varied substantially across household subgroups such as household income, age of the home, presence of air conditioning units, and use of portable air cleaners., Conclusions: Indoor PM 2.5 was substantially higher during wildfire-impacted periods versus the rest of the study. Indoor PM 2.5 and F inf were highly variable across households. Our results highlight potentially modifiable behaviors and characteristics that can be used in targeted intervention strategies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Natural ventilation is used to cool buildings and cut energy costs by inducing airflow through building openings without the use of mechanical ventilation and cooling systems. However, prior research has documented increased introduction of particles into indoor environments that are naturally ventilated, with associated health consequences. The recently updated ASHRAE Standard 62.1–2019: Ventilation for Acceptable Indoor Air Quality Natural Ventilation Procedure (NVP) prescribes opening sizes as a function of occupant density and geometry for use as a ventilation strategy, a change from the previous standard. The current work quantifies the indoor air quality impacts of implementing the Standard 62.1–2019 Natural Ventilation Procedure in the United States and compares it to the 62.1-specified ventilation rate procedure. This is done via coupled transient simulation of CONTAM 3.4 and EnergyPlus 9.1. Three pollutant classes were identified to represent a broad range of contaminants: outdoor-generated pollutants, pollutants generated indoors by humans, and pollutants generated indoors by the building itself. With boundary conditions from measured weather and outdoor pollutant data for 13 representative locations throughout the U.S., our modeling first found 41%–185% annual average increase in ventilation rates over its mechanical counterpart if the NVP is used across the geometries and occupant densities in the Standard. Due to elevated ventilation rates, the Natural Ventilation Procedure reduced building-generated and occupant-generated contaminant concentrations during occupied hours by an average of 17%–61% compared to the ventilation rate procedure. Outdoor-generated fine particles averaged 2.1–2.5 times the concentrations indoors when using the NVP as compared to mechanical ventilation with a MERV-8 filter and 7.8–10.4 times the concentration of a mechanical system with a MERV-13 filter. Both ventilation rates and concentrations were substantially climate-specific and somewhat window geometry-specific. We further showed that increased filtration is needed in many cases to keep up with increased effective NVP rates in the 2019 Standard if acceptable levels of indoor particles are to be achieved, and we offer suggestions for improving the Standard. • ASHRAE Standard 62.1–2019 prescribes natural ventilation rates significantly greater than mechanical prescriptions. • Predicted concentrations of pollutants generated indoors were 39–83% of mechanical ventilation concentrations. • Predicted concentrations of fine particle from outdoors were as much as 10 times greater than mechanical. • Filtration efficiency in mechanical systems drastically affects particle concentrations. • Several improvements to ASHRAE 62.1 Natural Ventilation Procedure are suggested. [ABSTRACT FROM AUTHOR]

[Display omitted] • The research team examined the effects of indoor environmental variables on absence rates in elementary schools. • Higher classroom ventilation rates significantly reduced illness-related absences. • Higher concentrations of indoor long-term monitored PM 2.5 were significantly associated with increased illness-related absences. • Although mechanically ventilated classrooms had relatively low indoor PM 2.5 , more rigorous control of indoor particles was still beneficial. This study monitored indoor environmental data in 144 classrooms in 31 schools in the Midwestern United States for two consecutive days every fall, winter, and spring during a two-year period; 3,105 pupils attended classrooms where the measurements were conducted. All classrooms were ventilated with mechanical systems that had recirculation; there were no operable exterior windows or doors. The daily absence rate at the student level and demographic data at the classroom level were collected. The overall mean ventilation rate, using outdoor air, was 5.5 L/s per person (the corresponding mean carbon dioxide concentrations were < 2,000 ppm), and the mean indoor PM 2.5 was 3.6 μg/m3. The annual illness-related absence rate at the classroom level was extracted from the student-level absence data and regressed on measured indoor environmental parameters. Significant associations were found. Every 1 L/s per person increase in ventilation rate was associated with a 5.59 decrease in days with absences per year. This corresponds to a 0.15% increase in the annual daily attendance rate. Every additional 1 μg/m3 of indoor PM 2.5 was associated with a 7.37 increase in days with absences per year. This corresponds to a 0.19% decrease in the annual daily attendance rate. No other relationships were significant. Present results agree with the previously demonstrated benefits of reduced absence rates when classroom ventilation is improved and provide additional evidence on the potential benefits of reducing indoor inhalable particles. Overall, reduced absence rates are expected to provide socioeconomic benefits and benefits for academic achievements, while higher ventilation rates and reduced particle levels will also contribute to reduced health risks, including those related to airborne respiratory pathogens. [ABSTRACT FROM AUTHOR]

Due to the global outbreak of infectious diseases over the years, airborne pathogen removal from the indoor environment has become a critical issue. Ultraviolet germicidal irradiation (UVGI) has been adopted as a strategic solution, and its implementation shows the enormous potential of inactivating airborne infectious pathogens. Despite extensive research, some critical research areas or gaps remain unidentified, while at the same time, few studies highlight the knowledge trend for UVGI air disinfection research necessary to guide investigators and practitioners. The purpose of this paper is to provide a thorough and objective analysis of UVGI research areas using bibliometric analysis. The available international standard known as the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) was followed for conducting this review. A comprehensive search covering the publication year up to December 2021 using Web of Science (WoS), Scopus, and PubMed databases was conducted. Also, the selection of studies, extraction of data, and assessments of risk of bias were also carried out. The characteristics and results of selected studies in evidence graphs, pie charts, network maps, and tables were presented and discussed. A total of 210 UVGI air disinfection-related publications were identified and reviewed. Based on the keyword co-occurrence analysis, document and direct citation analysis, 112 research keywords (see Table A1), and 6 core research journals were identified. Further, the results show that 3 countries and 7 organizational collaborators are at the centre of UVGI research. Based on the clustering analysis and comprehensive analysis of the findings, the research domain was developed, which grouped UVGI research into four themes. These findings are highly important for the advancement of UVGI. This paper provides a significant contribution by showing the knowledge pattern needed to facilitate further research and applications for both academia and industry stakeholders to improve indoor air quality. [Display omitted] • State-of-the-art knowledge of UVGI air disinfection. • The United States tops the list of countries at the center of UVGI research. • The majority (40.5%) of UVGI studies are laboratory-based experiments. • Prominent airborne pathogens and four knowledge domains in UVGI research. • Directions/recommendations for UVGI air disinfection research in the future. [ABSTRACT FROM AUTHOR]

Public school teachers represent one of the largest occupational groups in the United States and are vulnerable to job stress and burnout. School social and physical environments may be adversely impacting the health of teachers and other staff, though few studies have explored these relationships. We partnered with a suburban school district in Colorado to assess the association between school environmental quality, social climate, and staff member health. We modeled the number of self-reported frequent health symptoms (experienced at least once a week) using generalized linear models. School-level predictors of interest included: overall social climate scores (unitless), building operations report card (ORC) scores (unitless), and indoor air quality (IAQ) scores (unitless). In total, we had data from 134 staff members from 11 schools in the district. A majority (62%) of our participants were teachers, who reported a greater number of frequent (i.e., at least once a week) health symptoms (mean = 3.2 symptoms experienced at least once per week) compared to staff in other roles (mean = 2.3 symptoms per week). We found that a one standard-deviation (10.5) increase in the overall social climate score was associated with a 0.77-fold (95% CI: 0.60-0.99) change in the number of frequent health symptoms reported. However, this association was attenuated among teachers compared to other staff members. Our results suggested effect modification by social climate on the relationship between IAQ and health, albeit with some uncertainty. For participants with a school climate score below the mean, a one standard-deviation (10.5) increase in IAQ score was associated with a 0.49-fold (95% CI: 0.35-0.70) change in the number of frequently reported symptoms. Overall, our study suggests school climate may be associated with self-reported health symptoms, but that the benefits of improved school climates may not be as strong for teachers compared to other staff. Future work should assess perceived climate at the individual level to assess how staff roles impact how school environments are associated with health outcomes.