Pursuing perfection: an asthma quality improvement initiative in school-based health centers with community partners

School-based health centers as an approach to address health disparities among rural youth: A study protocol for a multilevel research framework

School-Based Health Centers (SBHCs) are important healthcare providers for children in medically underserved communities. While most existing research on SBHCs has focused on urban environments, this study protocol proposes a mixed-methods, multi-level research framework to evaluate the role of SBHCs in addressing health disparities among underserved children and adolescents in rural communities. The study area includes four high-poverty rural counties in New York State served by Bassett Healthcare Network that permits a comparison of school districts with SBHCs to those without SBHCs, all served by providers within the Bassett Healthcare Network. We employ a human ecological framework that integrates the micro layer of individuals and families, the meso layer of school districts and community institutions, and the macro layer of local and state policies. Our research framework first identifies the socioecological health risk factors, and then proposes innovative strategies to investigate how SBHCs impact them. We propose evaluating the impact of SBHCs on the individual (micro) level of child healthcare utilization using patient records data. At the meso level, we propose to investigate how School-SBHCs partnership may facilitate greater cross-agency collaboration and broader structural and social determinist of health to address health disparities. At the macro level, we propose to assess the impact of SBHCs and cross-agency collaboration on outcomes associated with a culture of community health. This study protocol will enable researchers to assess how SBHCs reduce rural health disparities, and provide evidence for organizational and public policy change.

Children with uncontrolled asthma from economically disadvantaged neighborhoods: Needs assessment and the development of a school-based telehealth and electronic inhaler monitoring system

BACKGROUND

Children from economically disadvantaged communities often encounter healthcare access barriers, increasing risk for poorly controlled asthma and subsequent healthcare utilization. This highlights the need to identify novel intervention strategies for these families.

OBJECTIVE

To better understand the needs and treatment preferences for asthma management in children from economically disadvantaged communities and to develop a novel asthma management intervention based on an initial needs assessment and stakeholder feedback.

METHODS

Semistructured interviews and focus groups were conducted with 19 children (10-17 years old) with uncontrolled asthma and their caregivers, 14 school nurses, 8 primary care physicians, and three school resource coordinators from economically disadvantaged communities. Interviews and focus groups were audio-taped and transcribed verbatim and then analyzed thematically to inform intervention development. Using stakeholder input, an intervention was developed for children with uncontrolled asthma and presented to participants for feedback to fully develop a novel intervention.

RESULTS

The needs assessment resulted in five themes: (1) barriers to quality asthma care, (2) poor communication across care providers, (3) problems identifying and managing symptoms and triggers among families, (4) difficulties with adherence, and (5) stigma. A proposed video-based telehealth intervention was proposed to stakeholders who provided favorable and informative feedback for the final development of the intervention for children with uncontrolled asthma.

CONCLUSIONS

Stakeholder input and feedback provided information critical to the development of a multicomponent (medical and behavioral) intervention in a school setting that uses technology to facilitate care, collaboration, and communication among key stakeholders to improve asthma management for children from economically disadvantaged neighborhoods.

Updates in school-based asthma management

PURPOSE OF REVIEW

School-based asthma management is an important component of pediatric asthma care that has the potential to provide more universal evidence-based asthma care to children and mitigate asthma-related health inequities. The purpose of this review is to highlight relevant developments in school-based asthma management over the past 2 years.

RECENT FINDINGS

There have been considerable recent scientific advances in school-based asthma management including robust clinical trials of environmental interventions in the classroom setting, school-nurse led interventions, stock albuterol policy changes, school-based telemedicine approaches and innovative methods to engage community stakeholders in research that have pushed the frontiers of school-based asthma care.

SUMMARY

Recent scientific work in school-based asthma management demonstrates the potential power of schools in providing access to guideline-based asthma care for all children with asthma and in improving their health outcomes. Future work should focus on the evaluation of methods to promote the adoption of school-based asthma management strategies in real-world practice and support evidence-based policy change and strategic partnerships to improve asthma health outcomes and produce meaningful public health impact for diverse children and families.

Elementary School-Based Health Centers and Access to Preventive and Asthma-Related Care Among Publicly Insured Children With Asthma in Georgia

OBJECTIVES

We assessed the effects of 3 new elementary school-based health centers (SBHCs) in disparate Georgia communities-predominantly non-Hispanic Black semi-urban, predominantly Hispanic urban, and predominantly non-Hispanic White rural-on asthma case management among children insured by Medicaid/Children's Health Insurance Program (CHIP).

METHODS

We used a quasi-experimental difference-in-differences analysis to measure changes in the treatment of children with asthma, Medicaid/CHIP, and access to an SBHC (treatment, n = 193) and children in the same county without such access (control, n = 163) in school years 2011-2013 and 2013-2018. Among children with access to an SBHC (n = 193), we tested for differences between users (34%) and nonusers of SBHCs. We used International Classification of Diseases diagnosis codes, Current Procedural Terminology codes, and National Drug Codes to measure well-child visits and influenza immunization; ≥3 asthma-related visits, asthma-relief medication, asthma-control medication, and ≥2 asthma-control medications; and emergency department visits during the child-school year.

RESULTS

We found an increase of about 19 (P = .01) to 33 (P < .001) percentage points in the probability of having ≥3 asthma-related visits per child-school year and an increase of about 22 (P = .003) to 24 (P < .001) percentage points in the receipt of asthma-relief medication, among users of the predominantly non-Hispanic Black and Hispanic SBHCs. We found a 19 (P = .01) to 29 (P < .001) percentage-point increase in receipt of asthma-control medication and a 15 (P = .03) to 30 (P < .001) percentage-point increase in receipt of ≥2 asthma-control medications among users. Increases were largest in the predominantly non-Hispanic Black SBHC.

CONCLUSION

Implementation and use of elementary SBHCs can increase case management and recommended medications among racial/ethnic minority and publicly insured children with asthma.

A scoping review of the use of quality improvement methods by community organizations in the United States, Australia, New Zealand, and Canada to improve health and well-being in community settings

Background

Health-care facilities have used quality improvement (QI) methods extensively to improve quality of care. However, addressing complex public health issues such as coronavirus disease 2019 and their underlying structural determinants requires community-level innovations beyond health care. Building community organizations’ capacity to use QI methods is a promising approach to improving community health and well-being.

Objectives

We explore how community health improvement has been defined in the literature, the extent to which community organizations have knowledge and skill in QI and how communities have used QI to drive community-level improvements.

Methods

Per a published study protocol, we searched Scopus, Web of Science, and Proquest Health management for articles between 2000 and 2019 from USA, Australia, New Zealand, and Canada. We included articles describing any QI intervention in a community setting to improve community well-being. We screened, extracted, and synthesized data. We performed a quantitative tabulation and a thematic analysis to summarize results.

Results

Thirty-two articles met inclusion criteria, with 31 set in the USA. QI approaches at the community level were the same as those used in clinical settings, and many involved multifaceted interventions targeting chronic disease management or health promotion, especially among minority and low-income communities. There was little discussion on how well these methods worked in community settings or whether they required adaptations for use by community organizations. Moreover, decision-making authority over project design and implementation was typically vested in organizations outside the community and did not contribute to strengthening the capability of community organizations to undertake QI independently.

Conclusion

Most QI initiatives undertaken in communities are extensions of projects in health-care settings and are not led by community residents. There is urgent need for additional research on whether community organizations can use these methods independently to tackle complex public health problems that extend beyond health-care quality.

School-Based Health Centers and Pediatric Practice

School-based health centers (SBHCs) are unique health care settings for our nation's school-aged children and adolescents. SBHCs represent the collaboration between the health and school communities to support the health and mental health needs and the academic achievements of children and adolescents, particularly students with health disparities or poor access to health care. SBHCs improve access to health care services for students by decreasing financial, geographic, age, and cultural barriers. This policy statement provides an overview of SBHCs, including the scope of services as well as some of the documented benefits and challenges. This policy statement also reviews the role of SBHCs in working with the pediatric medical home and provides recommendations that support the coordination of SBHCs with pediatric primary care providers and the pediatric medical home.

Policy Statement: Antibiotic Stewardship in Pediatrics

Antibiotic overuse contributes to antibiotic resistance, which is a threat to public health. Antibiotic stewardship is a practice dedicated to prescribing antibiotics only when necessary and, when antibiotics are considered necessary, promoting the use of the appropriate agent(s), dose, duration, and route of therapy to optimize clinical outcomes while minimizing the unintended consequences of antibiotic use. Because there are differences in common infectious conditions, drug-specific considerations, and the evidence surrounding treatment recommendations (eg, first-line therapy and duration of therapy) between children and adults, this statement provides specific guidance for the pediatric population. This policy statement discusses the rationale for inpatient and outpatient antibiotic stewardship programs (ASPs); essential personnel, infrastructure, and activities required; approaches to evaluating their effectiveness; and gaps in knowledge that require further investigation. Key guidance for both inpatient and outpatient ASPs are provided.

Show Me The Money…Saved! Cost Savings From Acute Asthma Care in the School-Based Health Center

Chronic school absenteeism directly affects educational outcomes while reducing school funding and reimbursement. Asthma is a prevalent disease associated with chronic absenteeism. This quality improvement project demonstrated classroom seat time preserved through use of school-based health centers (SBHC). The project also highlights the educational benefits, reduced emergency department utilization, potential cost savings to hospitals, and lower overall health care costs. Visit summary data were collected and analyzed to show quality asthma care and cost savings. Of 44 acute asthma visits that returned to class, an average classroom time of 3:42 hours were saved per student during the 2017-2018 academic year, resulting in a combined total of 166:07 hours saved. A minimum potential cost savings was estimated to be $67,770 for all 44 visits. Data analysis of structural, process, and outcome measures through quality improvement tools can demonstrate cost savings of SBHC care, which advocates funding for this pediatric care model.

Case analyses of state-sponsored asthma quality improvement interventions - benefits and technical assistance efforts

OBJECTIVE

A cross-case analysis was used to discover how two states benefited from expanded use of evaluation for asthma quality improvement initiatives. If an asthma quality improvement (QI) initiative is successfully evaluated, data can inform how to effectively integrate clinical practice guidelines and circumvent non-clinical reasons that interrupt QI projects such as low staff interest. This article addresses a gap in the literature on quality of evaluation support needed to improve and sustain asthma QI at local health care organizations by describing the similar discoveries observed at two independent QI statewide initiatives in Indiana and Montana.

METHODS

As part of a larger review, two states funded through the National Asthma Control Program at the Centers for Disease Control and Prevention were identified based on similarities in evaluation approaches. Each state used an iterative stakeholder-driven evaluation approach, mixed methods, process evaluation indicators, and active use of evaluation findings. The asthma QI initiatives and evaluations in Indiana and Montana were coordinated independent of each other.

RESULTS

Although both states found that asthma QI initiatives improved health outcomes, evaluation data were able to further pinpoint areas that would improve quality of technical support to health care organizations and identify markers of sustainability, such as nontraditional benefits to staff, and intervention sites.

CONCLUSION

Findings suggest that when evaluation is used to guide implementation, data are available to develop site-specific assistance and identify sustainability markers to prevent interruption of positive health outcomes associated with an asthma QI initiative.

Antibiotic Stewardship in Pediatrics

Antibiotic overuse contributes to antibiotic resistance, which is a threat to public health. Antibiotic stewardship is a practice dedicated to prescribing antibiotics only when necessary and, when antibiotics are considered necessary, promoting use of the appropriate agent(s), dose, duration, and route of therapy to optimize clinical outcomes while minimizing the unintended consequences of antibiotic use. Because there are differences in common infectious conditions, drug-specific considerations, and the evidence surrounding treatment recommendations (eg, first-line therapy, duration of therapy) between children and adults, this statement provides specific guidance for the pediatric population. This policy statement discusses the rationale for inpatient and outpatient antibiotic stewardship programs; essential personnel, infrastructure, and activities required; approaches to evaluating their effectiveness; and gaps in knowledge that require further investigation. Key guidance for both inpatient and outpatient antibiotic stewardship programs are provided.

School-Based Health Centers in the United States: Roots, Reality, and Potential

BACKGROUND

Given the amount of time children and adolescents spend in school, these locations may be ideal for simultaneously supporting young people's health and academic achievement. School-based health centers (SBHCs) not only bring care to students in accessible and familiar locations, these centers also provide guidance for young people during a life stage when they are establishing lifelong health behavior habits.

METHODS

This article examines the literature exploring the impact of SBHCs from the perspective of multiple stakeholder groups including students, guardians, school personnel, community members, providers, hospital administrators, public health officials, and insurers.

RESULTS

Studies describe the positive effects of SBHCs on students' health and educational outcomes. SBHCs are generally associated with decreased health care disparities among students, accelerated treatment, and increased school attendance.

CONCLUSIONS

Additional research exploring strategies for optimizing SBHC's economic efficiency and tailoring SBHC services to meet the needs of vulnerable patient populations is essential. Investigation into the impacts of SBHCs on community stakeholders outside of the student population is also vital.

Telehealth delivery of adherence and medication management system improves outcomes in inner-city children with asthma

Healthcare disparities exist in pediatric asthma in the United States. Children from minority, low-income families in inner-city areas encounter barriers to healthcare, leading to greater rates of poorly controlled asthma and healthcare utilization. Finding an effective way to deliver high-quality healthcare to this underserved population to improve outcomes, reduce morbidity and mortality, and reduce healthcare utilization is of the utmost importance. The purpose of this study was to assess the feasibility and efficacy of a novel school-based care delivery model that incorporates video-based telehealth (VBT) medical and self-management visits with electronic inhaler monitoring to improve asthma outcomes. Over a 6-month period, children from inner-city, low-income schools with uncontrolled asthma completed seven scheduled medical visits with an asthma specialist and five self-management visits with an adherence psychologist at school using VBT. Composite Asthma Severity Index (CASI) scores and electronic inhaler monitor data were recorded and analyzed. A total of 21 patients were enrolled in the study. Study subjects with higher baseline severity (CASI ≥ 4 at visit 1) demonstrated a greater reduction in their score than those with lower baseline severity (CASI < 4 at visit 1). The CASI domains showed improvement in daytime symptoms, nighttime symptoms, and exacerbations. Adherence results demonstrated a significant improvement in adherence from baseline to postintervention. Study retention was 100%. This study demonstrates that a multicomponent medical and behavioral interventional program delivered by VBT to a school-based setting is feasible and can significantly improve asthma outcomes and care in a challenging population.

A primary care learning collaborative to improve office systems and clinical management of pediatric asthma

OBJECTIVE

Pediatric asthma is a common, relapsing-remitting, chronic inflammatory airway disease that when uncontrolled often leads to substantial patient and health care system burden. Improving management of asthma in primary care can help patients stay well controlled.

METHODS

The Vermont Child Health Improvement Program (VCHIP) developed a quality improvement (QI) learning collaborative with a primary objective to improve clinical asthma management measures through improvement in primary care office systems to support asthma care. Seven months of medical record review data were evaluated for improvements on eight clinical asthma management measures. Pre and post office systems inventory (OSI) self-assessments detailing adherence to improvement strategies were analyzed for improvement. Logistic regressions were used to test for associations between OSI strategy post scores and the corresponding clinical asthma management measures by month seven.

RESULTS

This study found significant improvement from baseline to month seven on seven of the eight clinical asthma management measures and between pre and post OSI for seven of the nine strategies assessed (N = 19 practices). Additionally, one point higher average OSI scores on the assessment and monitoring of asthma severity, asthma control, asthma action plans, and asthma education strategies were associated with significantly greater odds of improvement in their respective clinical asthma management measures.

CONCLUSIONS

A QI learning collaborative approach in primary care can improve office systems and corresponding clinical management measures for pediatric patients with asthma. This suggests that linking specific office systems strategies to clinical measures may be a helpful tactic within the learning collaborative model.

Development of a quality improvement audit tool for the primary care of children with chronic wet cough using a modified Delphi consensus approach

AIM

In the absence of quality indicators (QIs) for the management of chronic wet cough, our study's aim was to determine whether consensus on QIs reflecting good primary health care, prior to referral for children with chronic wet cough, can be achieved.

METHODS

A questionnaire consisting of 10 QIs was developed by a clinical working group based on current evidence and guidelines on the management of chronic wet cough in children. Each indicator reflected the quality of care provided to children with chronic wet cough in primary care prior to referral. A modified Delphi consensus questionnaire was undertaken involving expert paediatric respiratory clinicians and general paediatricians who graded the importance of each indicator for the purposes above. We a priori defined that consensus was considered achieved if >75% agreed on the indicator.

RESULTS

Twenty-two specialists (from Brisbane, Melbourne, Perth and Canberra) participated in the survey. The cumulative number of years of their respiratory experience was 324 and that of general clinical practice was 504. Consensus was achieved in all 10 QIs, with 6 reaching 100% agreement. Mean agreement for the 10 items was 97%.

CONCLUSION

As complete consensus was achieved on these QIs, it can be used as a provisional clinical audit tool and can guide the development of a robust audit tool for primary care clinical practice to assist with quality improvement initiatives.

Taming Asthma in School-Aged Children: A Comprehensive Review

Asthma is the most common chronic disease of childhood and the leading cause of childhood morbidity as measured by school absences, emergency department visits, and hospitalizations. Multiple factors play a role in the development, treatment and prevention of childhood asthma including racial/ethnic and socioeconomic disparities, both the home and school environments, and medication use. The goals of this review are to summarize these aspects of asthma in school-aged children and to present an updated review of medications as it relates to treatment strategies that will help in the care of these children. We conclude that phenotypic heterogeneity and appropriate environmental assessments and interventions are important considerations in the management of childhood asthma.

The value of using schools as community assets for health

In planning, designing, procuring and ensuring delivery of improved services ('commissioning') for the school age population, the outcomes should be students who are healthy to learn and who learn to be healthy. Intuitively, linking education and health development together within the wider learning environment seems a good start to planning school health. However there has been a shortage of either theoretical models that can span different settings or experimental research that demonstrates improved community health. Is there evidence that the wider learning environment provided in a school is valuable in improving health? An initial scoping exercise identified domains of health where there was a promise of health gain. International literature on school health outcomes using the framework of Asset-Based Community Development (ABCD) has been reviewed. It was found that research on a variety of interventions was relevant to schools as an asset for public health. Effective areas for health gain were identified for local planning and evaluation using this community model. However, none of the studies reviewed was originally designed to test schools as assets and most of the research lacked methodological rigour, especially regarding children in low income countries. The ABCD model could help national governments develop resources for both education and health, but there is a global need to generate better quality evidence. Then people who commission for their local communities can make more effective use of these multifaceted assets to improve health and education outcomes for children.

Obesity and asthma: pathophysiology and implications for diagnosis and management in primary care

The effects of obesity on asthma diagnosis, control, and exacerbation severity are increasingly recognized; however, the underlying pathophysiology of this association is poorly understood. Mainstream clinical practice has yet to adopt aggressive management of obesity as a modifiable risk factor in asthma care, as is the case with a risk factor like tobacco or allergen exposure. This review summarizes existing data that support the pathophysiologic mechanisms underlying the association between obesity and asthma, as well as the current and future state of treatment for the obese patient with asthma. Our review suggests that evidence of chronic inflammatory response linking obesity and asthma indicates a need to address obesity during asthma management, possibly using patient-centered approaches such as shared decision making. There is a need for research to better understand the mechanisms of asthma in the obese patient and to develop new therapies specifically targeted to this unique patient population.

Community-based interventions in asthma

Community and public health interventions provide potentially powerful means of decreasing morbidity, hospitalizations, emergency room visits, and mortality from asthma. This chapter thus provides an overview of community-based interventions, which have been demonstrated to be effective-and/or ineffective-in reducing the burden of disease, including development of asthma coalitions, interventions for both provider and patient education, environmental controls to reduce exposure to asthma triggers, and institutional policy and systems change. Perhaps most important is the demonstrated effect of integrated, comprehensive approaches to asthma management and control. A multidisciplinary approach spanning T1 through T4 translational research, coupled with public health activities is promising and has already demonstrated success in reducing the burden of disease.

Asthma interventions in primary schools--a review

OBJECTIVE

To explore, in depth, the literature for evidence supporting asthma interventions delivered within primary schools and to identify any "gaps" in this research area.

METHODS

A literature search using electronic search engines (i.e. Medline, PubMed, Education Resources Information Center (ERIC), International Pharmaceutical Abstracts (IPA), Cumulative Index to Nursing and Allied Health Literature (CINAHL), Embase and Informit) and the search terms "asthma", "asthma intervention" and "school-based asthma education program" (and derivatives of these keywords) was conducted.

RESULTS

Twenty-three articles met the inclusion criteria; of these eight were Randomised Controlled Trials. There was much variety in the type, content, delivery and outcome measures in these 23 studies. The most common intervention type was asthma education delivery. Most studies demonstrated improvement in clinical and humanistic markers, for example, asthma symptoms medication use (decrease in reliever medication use or decrease in the need for rescue oral steroid), inhaler use technique and spacer use competency, lung function and quality of life. Relatively few studies explored the effect of the intervention on academic outcomes. Most studies did not report on the sustainability or cost effectiveness of the intervention tested. Another drawback in the literature was the lack of details about the intervention and inconsistency in instruments selected for measuring outcomes.

CONCLUSION

School-based asthma interventions regardless of their heterogeneity have positive clinical, humanistic, health economical and academic outcomes.

School-based health centers in an era of health care reform: building on history

School-based health centers (SBHCs) provide a variety of health care services to youth in a convenient and accessible environment. Over the past 40 years, the growth of SBHCs evolved from various public health needs to the development of a specific collaborative model of care that is sensitive to the unique needs of children and youth, as well as to vulnerable populations facing significant barriers to access. The SBHC model of health care comprises of on-school site health care delivery by an interdisciplinary team of health professionals, which can include primary care and mental health clinicians. Research has demonstrated the SBHCs' impacts on delivering preventive care, such as immunizations; managing chronic illnesses, such as asthma, obesity, and mental health conditions; providing reproductive health services for adolescents; and even improving youths' academic performance. Although evaluation of the SBHC model of care has been complicated, results have thus far demonstrated increased access to care, improved health and education outcomes, and high levels of satisfaction. Despite their proven success, SBHCs have consistently faced challenges in securing adequate funding for operations and developing effective financial systems for billing and reimbursement. Implementation of health care reform (The Patient Protection and Affordable Care Act [P.L. 111-148]) will profoundly affect the health care access and outcomes of children and youth, particularly vulnerable populations. The inclusion of funding for SBHCs in this legislation is momentous, as there continues to be increased demand and limited funding for affordable services. To better understand how this model of care has and could further help promote the health of our nation's youth, a review is presented of the history and growth of SBHCs and the literature demonstrating their impacts. It may not be feasible for SBHCs to be established in every school campus in the country. However, the lessons learned from the synergy of the health and school settings have major implications for the delivery of care for all providers concerned with improving the health and well-being of children and adolescents.

School-based health centers and pediatric practice

School-based health centers (SBHCs) have become an important method of health care delivery for the youth of our nation. Although they only represent 1 aspect of a coordinated school health program approach, SBHCs have provided access to health care services for youth confronted with age, financial, cultural, and geographic barriers. A fundamental principle of SBHCs is to create an environment of service coordination and collaboration that addresses the health needs and well-being of youth with health disparities or poor access to health care services. Some pediatricians have concerns that these centers are in conflict with the primary care provider's medical home. This policy provides an overview of SBHCs and some of their documented benefits, addresses the issue of potential conflict with the medical home, and provides recommendations that support the integration and coordination of SBHCs and the pediatric medical home practice.

The moderating effect of school type on the relationship between school-based health centers and the learning environment

School-Based Health Centers (SBHCs) have improved access to primary and preventive health care for underserved children and youth by bringing comprehensive health services into the schools while addressing critical health problems that make it difficult for students to learn. Despite the findings on the positive effects of SBHCs on health outcomes, the literature investigating the relationship between SBHCs and the learning environment is scant. This study utilizes a quasi experimental study to investigate the moderating effects of school type on the relationship between school based health centers and the learning environment. Findings indicate that SBHCs in middle and elementary schools are associated with greater levels of school engagement and satisfaction with the learning environment than those in high schools.

Aerosol particles generated by diesel-powered school buses at urban schools as a source of children's exposure

Various heath effects in children have been associated with exposure to traffic-related particulate matter (PM), including emissions from school buses. In this study, the indoor and outdoor aerosol at four urban elementary schools serviced by diesel-powered school buses was characterized with respect to the particle number concentrations and size distributions as well as the PM2.5 mass concentrations and elemental compositions. It was determined that the presence of school buses significantly affected the outdoor particle size distribution, specifically in the ultrafine fraction. The time-weighted average of the total number concentration measured outside the schools was significantly associated with the bus and the car counts. The concentration increase was consistently observed during the morning drop-off hours and in most of the days during the afternoon pick-up period (although at a lower degree). Outdoor PM2.5 mass concentrations measured at schools ranged from 3.8 to 27.6 µg m-3. The school with the highest number of operating buses exhibited the highest average PM2.5 mass concentration. The outdoor mass concentrations of elemental carbon (EC) and organic carbon (OC) were also highest at the school with the greatest number of buses. Most (47/55) correlations between traffic-related elements identified in the outdoor PM2.5 were significant with elements identified in the indoor PM2.5. Significant associations were observed between indoor and outdoor aerosols for EC, EC/OC, and the total particle number concentration. Day-to-day and school-to-school variations in Indoor/Outdoor (I/O) ratios were related to the observed differences in opening windows and doors, which enhanced the particle penetration, as well as indoor activities at schools. Overall, the results on I/O ratio obtained in this study reflect the sizes of particles emitted by diesel-powered school bus engines (primarily, an ultrafine fraction capable of penetrating indoors).