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Widespread North American wildfires in 2023 led to exposure to ambient wildfire smoke outside of traditionally wildfire-prone regions. The objective was to evaluate levels of indoor air pollutants in relation to ambient wildfire smoke exposure in eastern Massachusetts. Using a real-time multipollutant sensor system in five Boston area households, this study assessed indoor fine particulate matter (PM 2.5 ), nitrogen dioxide (NO 2 ), and total volatile organic compound concentrations (TVOC) two days before and during days of hazardous wildfire smoke exposure (smoke days). The relationship between ambient PM 2.5 from regulatory monitors and indoor PM 2.5 before and during smoke days was investigated by mixed effects linear regression. During smoke days and the preceding non-smoke days, median indoor PM 2.5 was 9.9 µg/m 3 and 3.5 µg/m 3 ( p  < 0.001), respectively; median NO 2 was 20.5 ppb and 18.4 ppb ( p  = 0.11); median TVOC was 6,715 µg/m 3 and 5,361 µg/m 3 ( p  = 0.35). A 1% increase in ambient PM 2.5 was associated with a 0.93% increase in indoor PM 2.5 on smoke days (95% CI, 0.54%-1.32%) and a 0.34% increase on non-smoke days (95% CI, 0.17%-0.66%), though interaction testing of smoke day status was not statistically significant ( p  = 0.14). In Northeastern US homes, indoor PM 2.5 increased significantly during ambient wildfire smoke exposure, which may reflect increased infiltration and increased indoor particle-generating activities during smoke days. Implications : This study reports on household exposure to wildfire smoke in eastern Massachusetts, finding that indoor PM 2.5 more than doubled compared to preceding non-smoke days, while indoor NO 2 and TVOC did not significantly rise. Though the generalizability of this study is limited by the small number of homes studied, the findings suggest that more investigation is needed to understand indoor air pollution during future wildfire smoke exposure in regions not traditionally wildfire-prone and to inform mitigation efforts.

Background: Since there are known adverse health impacts of traffic-related air pollution, while at the same time there are potential health benefits from greenness, it is important to examine more closely the impacts of these factors on indoor air quality in urban schools., Objective: This study investigates the association of road proximity and urban greenness to indoor traffic-related fine particulate matter (PM 2.5 ), nitrogen dioxide (NO 2 ), and black carbon (BC) in inner-city schools., Methods: PM 2.5 , NO 2 , and BC were measured indoors at 74 schools and outdoors at a central urban over a 10-year period. Seasonal urban greenness was estimated using the Normalized Difference Vegetation Index (NDVI) with 270 and 1230 m buffers. The associations between indoor traffic-related air pollution and road proximity and greenness were investigated with mixed-effects models., Results: The analysis showed linear decays of indoor traffic-related PM 2.5 , NO 2 , and BC by 60%, 35%, and 22%, respectively for schools located at a greater distance from major roads. The results further showed that surrounding school greenness at 270 m buffer was significantly associated (p < 0.05) with lower indoor traffic-related PM 2.5 : -0.068 (95% CI: -0.124, -0.013), NO 2 : -0.139 (95% CI: -0.185, -0.092), and BC: -0.060 (95% CI: -0.115, -0.005). These associations were stronger for surrounding greenness at a greater distance from the schools (buffer 1230 m) PM 2.5 : -0.101 (95% CI: -0.156, -0.046) NO 2 : -0.122 (95% CI: -0.169, -0.075) BC: -0.080 (95% CI: -0.136, -0.026). These inverse associations were stronger after fully adjusting for regional pollution and meteorological conditions., Impact Statement: More than 90% of children under the age of 15 worldwide are exposed to elevated air pollution levels exceeding the WHO's guidelines. The study investigates the impact that urban infrastructure and greenness, in particular green areas and road proximity, have on indoor exposures to traffic-related PM 2.5 , NO 2 , and BC in inner-city schools. By examining a 10-year period the study provides insights for air quality management, into how road proximity and greenness at different buffers from the school locations can affect indoor exposure., (© 2024. The Author(s).)

Purpose of Review: Higher asthma prevalence and morbidity are seen in inner-city areas, disproportionately affecting low-income families living in substandard housing. Children within these families experience more frequent asthma exacerbations, acute care and emergency department visits, and hospitalizations, thus characterizing severe asthma. In this review, we assess recent published literature focused on indoor and outdoor exposures that contribute to the development and morbidity of asthma., Recent Findings: Many urban environmental exposures contribute to asthma burden, including tobacco/e-cigarette smoke, pest allergens, molds, and possibly synthetic chemicals such as phthalates and bisphenol A, radon, and volatile organic compounds. Individuals living in inner-city areas also experience higher levels of air pollutants and ambient heat, further perpetuating asthma incidence and severity., Summary: This article summarizes the latest advances and provides direction for future research on risk factors, interventions, and public policy to help alleviate the burden of asthma due to urban environment exposures., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Objective: The School Inner-City Asthma Intervention Study 2 (SICAS 2) tested interventions to reduce exposures in classrooms of students with asthma. The objective of this post-hoc analysis was limited to evaluating the effect of high-efficiency particulate (HEPA) filtration interventions on mold levels as quantified using the Environmental Relative Moldiness Index (ERMI) and the possible improvement in the students' asthma, as quantified by spirometry testing., Methods: Pre-intervention dust samples were collected at the beginning of the school year from classrooms and corresponding homes of students with asthma ( n  = 150). Follow-up dust samples were collected in the classrooms at the end of the HEPA or Sham intervention. For each dust sample, ERMI values and the Group 1 and Group 2 mold levels (components of the ERMI metric) were quantified. In addition, each student's lung function was evaluated by spirometry testing, specifically the percentage predicted forced expiratory volume at 1 sec (FEV1%), before and at the end of the intervention., Results: For those students with a higher Group 1 mold level in their pre-intervention classroom than home ( n  = 94), the FEV1% results for those students was significantly ( p  < 0.05) inversely correlated with the Group 1 level in their classrooms. After the HEPA intervention, the average Group 1 and ERMI values were significantly lowered, and the average FEV1% test results significantly increased by an average of 4.22% for students in HEPA compared to Sham classrooms., Conclusions: HEPA intervention in classrooms reduced Group 1 and ERMI values, which corresponded to improvements in the students' FEV1% test results.

Background: School classrooms, where students spend the majority of their time during the day, are the second most important indoor microenvironment for children., Objective: We investigated factors influencing classroom exposures to fine particulate matter ( PM 2.5 ), black carbon (BC), and nitrogen dioxide ( NO 2 ) in urban schools in the northeast United States., Methods: Over the period of 10 y (2008-2013; 2015-2019) measurements were conducted in 309 classrooms of 74 inner-city schools during fall, winter, and spring of the academic period. The data were analyzed using adaptive mixed-effects least absolute shrinkage and selection operator (LASSO) regression models. The LASSO variables included meteorological-, school-, and classroom-based covariates., Results: LASSO identified 10, 10, and 11 significant factors ( p < 0.05 ) that were associated with indoor PM 2.5 , BC, and NO 2 exposures, respectively. The overall variability explained by these models was R 2 = 0.679 , 0.687, and 0.621 for PM 2.5 , BC, and NO 2 , respectively. Of the model's explained variability, outdoor air pollution was the most important predictor, accounting for 53.9%, 63.4%, and 34.1% of the indoor PM 2.5 , BC, and NO 2 concentrations. School-based predictors included furnace servicing, presence of a basement, annual income, building type, building year of construction, number of classrooms, number of students, and type of ventilation that, in combination, explained 18.6%, 26.1%, and 34.2% of PM 2.5 , BC, and NO 2 levels, whereas classroom-based predictors included classroom floor level, classroom proximity to cafeteria, number of windows, frequency of cleaning, and windows facing the bus area and jointly explained 24.0%, 4.2%, and 29.3% of PM 2.5 , BC, and NO 2 concentrations, respectively., Discussion: The adaptive LASSO technique identified significant regional-, school-, and classroom-based factors influencing classroom air pollutant levels and provided robust estimates that could potentially inform targeted interventions aiming at improving children's health and well-being during their early years of development. https://doi.org/10.1289/EHP10007.

Importance: School and classroom allergens and particles are associated with asthma morbidity, but the benefit of environmental remediation is not known., Objective: To determine whether use of a school-wide integrated pest management (IPM) program or high-efficiency particulate air (HEPA) filter purifiers in the classrooms improve asthma symptoms in students with active asthma., Design, Setting, and Participants: Factorial randomized clinical trial of a school-wide IPM program and HEPA filter purifiers in the classrooms was conducted from 2015 to 2020 (School Inner-City Asthma Intervention Study). There were 236 students with active asthma attending 41 participating urban elementary schools located in the Northeastern US who were randomized to IPM by school and HEPA filter purifiers by classroom. The date of final follow-up was June 20, 2020., Interventions: The school-wide IPM program consisted of application of rodenticide, sealing entry points, trap placement, targeted cleaning, and brief educational handouts for school staff. Infestation was assessed every 3 months, with additional treatments as needed. Control schools received no IPM, cleaning, or education. Classroom portable HEPA filter purifiers were deployed and the filters were changed every 3 months. Control classrooms received sham HEPA filters that looked and sounded like active HEPA filter purifiers. Randomization was done independently (split-plot design), with matching by the number of enrolled students to ensure a nearly exact 1:1 student ratio for each intervention with 118 students randomized to each group. Participants, investigators, and those assessing outcomes were blinded to the interventions., Main Outcomes and Measures: The primary outcome was the number of symptom-days with asthma during a 2-week period. Symptom-days were assessed every 2 months during the 10 months after randomization., Results: Among the 236 students who were randomized (mean age, 8.1 [SD, 2.0] years; 113 [48%] female), all completed the trial. At baseline, the 2-week mean was 2.2 (SD, 3.9) symptom-days with asthma and 98% of the classrooms had detectable levels of mouse allergen. The results were pooled because there was no statistically significant difference between the 2 interventions (P = .18 for interaction). During a 2-week period, the mean was 1.5 symptom-days with asthma after use of the school-wide IPM program vs 1.9 symptom-days after no IPM across the school year (incidence rate ratio, 0.71 [95% CI, 0.38-1.33]), which was not statistically significantly different. During a 2-week period, the mean was 1.6 symptom-days with asthma after use of HEPA filter purifiers in the classrooms vs 1.8 symptom-days after use of sham HEPA filter purifiers across the school year (incidence rate ratio, 1.47 [95% CI, 0.79-2.75]), which was not statistically significantly different. There were no intervention-related adverse events., Conclusions and Relevance: Among children with active asthma, use of a school-wide IPM program or classroom HEPA filter purifiers did not significantly reduce symptom-days with asthma. However, interpretation of the study findings may need to consider allergen levels, particle exposures, and asthma symptoms at baseline., Trial Registration: ClinicalTrials.gov Identifier: NCT02291302.

Background: Asthma is among the most common chronic diseases of children in the United States (US). Mold exposures have been linked to asthma development and exacerbation. In homes, mold exposures have been quantified using the Environmental Relative Moldiness Index (ERMI), and higher home ERMI values have been linked to occupant asthma., Objective: In this analysis of the School Inner-City Asthma Study (SICAS), we aimed to evaluate the ERMI's applicability to measuring mold in schools compared with homes and to examine the prevalence of asthma in relationship to students' demographics and the physical characteristics of school buildings., Methods: Northeastern US schools (n = 32) and homes (n = 33) were selected, and the 36 ERMI molds were quantified in a dust sample from each classroom (n = 114) or home. School building characteristics data were collected from SICAS. Asthma prevalence and student demographics data were obtained from government websites. Linear regression and mixed models were fit to assess the association of the current asthma prevalence and physical characteristics of the school, make-up of the student body, and the ERMI metric., Results: Levels of outdoor group 2 molds were significantly (P < .01) greater in schools compared with homes. The presence of air-conditioning in school buildings correlated significantly (P = .02) with lower asthma prevalence., Conclusion: The prevalence of asthma in student bodies is associated with many factors in schools and homes., (Copyright © 2020 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Children spend over 6 h a day in schools and have higher asthma morbidity from school environmental exposures. The present study aims to determine indoor and outdoor possible sources affecting indoor PM 2.5 in classrooms. Weeklong indoor PM 2.5 samples were collected from 32 inner-city schools from a Northeastern U.S. community during three seasons (fall, winter and spring) during the years 2009 to 2013. Concurrently, daily outdoor PM 2.5 samples were taken at a central monitoring site located at a median distance of 4974 m (range 1065-11,592 m) from the schools. Classroom indoor concentrations of PM 2.5 (an average of 5.2 μg/m 3 ) were lower than outdoors (an average of 6.5 μg/m 3 ), and these averages were in the lower range compared to the findings in other schools' studies. The USEPA PMF model was applied to the PM 2.5 components measured simultaneously from classroom indoor and outdoor to estimate the source apportionment. The major sources (contributions) identified across all seasons of indoor PM 2.5 were secondary pollution (41%) and motor vehicles (17%), followed by Calcium (Ca)-rich particles (12%), biomass burning (15%), soil dust (6%), and marine aerosols (4%). Likewise, the major sources of outdoor PM 2.5 across all seasons were secondary pollution (41%) and motor vehicles (26%), followed by biomass burning (17%), soil dust (7%), road dust (3%), and marine aerosols (1%). Secondary pollution was the greatest contributor to indoor and outdoor PM 2.5 over all three seasons, with the highest contribution during spring with 53% to indoor PM 2.5 and 45% to outdoor PM 2.5 . Lower contributions of this source during fall and winter are most likely attributed to less infiltration indoors. In contrast, the indoor contribution of motor vehicles source was highest in the fall (29%) and winter (25%), which was presumably categorized by a local source. From the relationship between indoor-to-outdoor sulfur ratios and each source contribution, we also estimated the local and regional influence on indoor PM 2.5 concentration. Overall, the observed differences to indoor PM 2.5 are related to seasonality, and the distinct characteristics and behavior of each classroom/school., (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Ambient and home exposure to nitrogen dioxide (NO 2 ) causes asthma symptoms and decreased lung function in children with asthma. Little is known about the health effects of school classroom pollution exposure., Objective: We aimed to determine the effect of indoor classroom NO 2 on lung function and symptoms in inner-city school children with asthma., Methods: Children enrolled in the School Inner-City Asthma Study were followed for 1 academic year. Subjects performed spirometry and had fraction of exhaled nitric oxide values measured twice during the school year at school. Classroom NO 2 was collected by means of passive sampling for 1-week periods twice per year, coinciding with lung function testing. Generalized estimating equation models assessed lung function and symptom relationships with the temporally nearest classroom NO 2 level., Results: The mean NO 2 value was 11.1 ppb (range, 4.3-29.7 ppb). In total, exposure data were available for 296 subjects, 188 of whom had complete spirometric data. At greater than a threshold of 8 ppb of NO 2 and after adjusting for race and season (spirometry standardized by age, height, and sex), NO 2 levels were associated highly with airflow obstruction, such that each 10-ppb increase in NO 2 level was associated with a 5% decrease in FEV 1 /forced vital capacity ratio (β = -0.05; 95% CI, -0.08 to -0.02; P = .01). Percent predicted forced expiratory flow between the 25th and 75th percentile of forced vital capacity was also inversely associated with higher NO 2 exposure (β = -22.8; 95% CI, -36.0 to -9.7; P = .01). There was no significant association of NO 2 levels with percent predicted FEV 1 , fraction of exhaled nitric oxide, or asthma symptoms. Additionally, there was no effect modification of atopy on lung function or symptom outcomes., Conclusion: In children with asthma, indoor classroom NO 2 levels can be associated with increased airflow obstruction., (Copyright © 2017 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Outdoor air pollution penetrates buildings and contributes to total indoor exposures. We investigated the relationship of indoor to outdoor particulate matter in inner-city school classrooms. The School Inner City Asthma Study investigates the effect of classroom-based environmental exposures on students with asthma in the northeast United States. Mixed effects linear models were used to determine the relationships between indoor PM 2.5 (particulate matter) and black carbon (BC), and their corresponding outdoor concentrations, and to develop a model for predicting exposures to these pollutants. The indoor-outdoor sulfur ratio was used as an infiltration factor of outdoor fine particles. Weeklong concentrations of PM 2.5 and BC in 199 samples from 136 classrooms (30 school buildings) were compared with those measured at a central monitoring site averaged over the same timeframe. Mixed effects regression models found significant random intercept and slope effects, which indicate that: (1) there are important PM 2.5 sources in classrooms; (2) the penetration of outdoor PM 2.5 particles varies by school and (3) the site-specific outside PM 2.5 levels (inferred by the models) differ from those observed at the central monitor site. Similar results were found for BC except for lack of indoor sources. The fitted predictions from the sulfur-adjusted models were moderately predictive of observed indoor pollutant levels (out of sample correlations: PM 2.5 : r 2 =0.68, BC; r 2 =0.61). Our results suggest that PM 2.5 has important classroom sources, which vary by school. Furthermore, using these mixed effects models, classroom exposures can be accurately predicted for dates when central site measures are available but indoor measures are not available.

Background: Endotoxin exposure is associated with airway inflammation. Children spend 6 to 8 h/d in school, yet the effect of school-specific endotoxin exposure on asthma morbidity is not well understood., Methods: In this longitudinal cohort study, 248 students with asthma, from 38 inner-city schools, underwent baseline phenotyping and follow-up. Clinical outcomes were evaluated throughout the academic school year and linked to classroom-specific dust and air endotoxin levels as well as home dust endotoxin levels. The primary outcome was maximum asthma symptom-days per 2-week period., Results: Classrooms had higher settled dust endotoxin levels compared with homes (14.3 endotoxin unit/mg vs 11.3 endotoxin unit/mg; P = .02). Airborne endotoxin levels exceeding recommended occupational exposure limits for adults were recorded in 22.0% of classrooms. Classroom air endotoxin levels were independently associated with increased maximum symptom-days in children with nonatopic asthma, but not in those with atopic asthma (interaction P = .03). Adjusting for home exposures, classroom endotoxin exposure was independently associated with a dose-dependent increase in asthma symptom-days for children with nonatopic asthma (adjusted incidence rate ratio, 1.16 [95% CI, 1.03-1.31]; P = .02). In these subjects, maximum symptom-days increased by 1.3 days for each 14-day period when comparing students in classrooms with the lowest endotoxin levels compared with average measured levels., Conclusions: Inner-city children with asthma are exposed to high levels of airborne endotoxin at school, resulting in increased asthma symptoms in children with nonatopic asthma. Mitigation of school-related exposures may represent a strategy to decrease asthma morbidity in this population., Trial Registry: ClinicalTrials.gov; No.: NCT01756391; URL: www.clinicaltrials.gov.

Background: Previous research has found relationships between specific indoor environmental exposures and exacerbation of asthma., Objectives: In this review we provide an updated summary of knowledge from the scientific literature on indoor exposures and exacerbation of asthma., Methods: Peer-reviewed articles published from 2000 to 2013 on indoor exposures and exacerbation of asthma were identified through PubMed, from reference lists, and from authors' files. Articles that focused on modifiable indoor exposures in relation to frequency or severity of exacerbation of asthma were selected for review. Research findings were reviewed and summarized with consideration of the strength of the evidence., Results: Sixty-nine eligible articles were included. Major changed conclusions include a causal relationship with exacerbation for indoor dampness or dampness-related agents (in children); associations with exacerbation for dampness or dampness-related agents (in adults), endotoxin, and environmental tobacco smoke (in preschool children); and limited or suggestive evidence for association with exacerbation for indoor culturable Penicillium or total fungi, nitrogen dioxide, rodents (nonoccupational), feather/down pillows (protective relative to synthetic bedding), and (regardless of specific sensitization) dust mite, cockroach, dog, and dampness-related agents., Discussion: This review, incorporating evidence reported since 2000, increases the strength of evidence linking many indoor factors to the exacerbation of asthma. Conclusions should be considered provisional until all available evidence is examined more thoroughly., Conclusion: Multiple indoor exposures, especially dampness-related agents, merit increased attention to prevent exacerbation of asthma, possibly even in nonsensitized individuals. Additional research to establish causality and evaluate interventions is needed for these and other indoor exposures.

Desktop dust has been studied as a source of food allergen, but not as a source of potential aeroallergen exposure. Thirty-six wiped samples from desktop surfaces were collected from preschools and schools. Samples were analyzed for detectable levels of common aeroallergens including Alternaria, cockroach, dog, dust mite, cat, mouse, and rat allergens by immunoassay. Mouse allergen was the most prevalent, detectable in 97.2% of samples. Cat allergen was detectable in 80.6% of samples, and dog allergen was detectable in 77.8% of samples. Other allergens were not as prevalent. Mouse was the only allergen that was highly correlated with settled floor dust collected from the same rooms (r = 0.721, P < 0.001). This is the first study to detect aeroallergens on desktop surfaces by using moist wipes. Allergens for mouse, cat, and dog were highly detectable in wipes with mouse desktop surface levels correlating with levels in vacuumed floor dust., (© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Objective: Exposure to indoor pollutants and allergens has been speculated to cause asthma symptoms and exacerbations and influence the risk of developing asthma. The aim of this article is to review the medical literature regarding the role of the indoor environment on inner-city childhood asthma., Data Sources: A literature search was performed in PubMed. Studies focusing on inner-city indoor allergen, childhood asthma, and environmental controls were included., Results: The prevalence of asthma in children is increasing especially in inner-city area. Exposure to high levels of indoor allergens and pollutants has been related to asthma development. Studies have shown that mouse, cockroach, pets, dust mite, mold, tobacco smoke, endotoxin and nitrogen dioxide are the important exposures. Recent studies have shown that indoor environmental control is beneficial in reducing asthma morbidity and development., Conclusions: Inner-city children are exposed to various indoor allergens and pollutants that may lead to asthma development and exacerbation of existing asthma. Multifaceted environmental controls are beneficial in improving asthma symptom and maybe a viable prevention strategy. Further prospective studies of environmental intervention are needed to further identify effective strategies to improve and prevent asthma symptoms in inner-city children.

Background: Children spend a significant amount of time in school. Little is known about the role of allergen exposure in school environments and asthma morbidity., Objectives: The School Inner-City Asthma Study (SICAS) is a National Institutes of Health (NIH)-funded prospective study evaluating the school/classroom-specific risk factors and asthma morbidity among urban children., Methods/results: This article describes the design, methods, and important lessons learned from this extensive investigation. A single center is recruiting 500 elementary school-aged children, all of whom attend inner-city metropolitan schools. The primary hypothesis is that exposure to common indoor allergens in the classroom will increase the risk of asthma morbidity in children with asthma, even after controlling for home allergen exposures. The protocol includes screening surveys of entire schools and baseline eligibility assessments obtained in the spring prior to the academic year. Extensive baseline clinical visits are being conducted among eligible children with asthma during the summer prior to the academic school year. Environmental classroom/school assessments including settled dust and air sampling for allergen, mold, air pollution, and inspection data are collected twice during the academic school year and one home dust sample linked to the enrolled student. Clinical outcomes are measured every 3 months during the academic school year., Conclusion: The overall goal of SICAS is to complete the first study of its kind to better understand school-specific urban environmental factors on childhood asthma morbidity. We also discuss the unique challenges related to school-based urban research and lessons being learned from recruiting such a cohort.