For children with asthma, exposure to indoor air pollution increases the risk of a serious asthma exacerbation, which can be life-threatening. Interventions aimed at improving indoor air quality, including use of a portable air cleaner with a high-efficiency particulate air (HEPA) filter, can reduce this risk, but the effectiveness, feasibility and acceptability of HEPA air cleaners varies by setting. In collaboration with a community health worker (CHW) delivered asthma education program, the investigators are conducting a randomized clinical trial to evaluate the effectiveness of HEPA air cleaners to improve indoor air quality and child asthma health in South King County of Washington state, a vulnerable community impacted by air pollution from airports and highway traffic. Key features of the Airports, Air Quality and Asthma (AAA) design include integration of CHWs into study procedures, including CHWs recruited from community-based organizations, into multiple aspects of the trial protocol. The investigators aim to recruit up to N=60 children with asthma randomized into intervention and control groups in a 1:1 ratio, conduct baseline assessments of indoor air quality and airway health, and collect repeated assessments of air quality and airway health during the three-month intervention period and after the trial concludes. Study findings will inform future approaches to integrate HEPA air cleaners into existing CHW asthma education programs in this and similar communities.

Communities in proximity to airports face increased exposures to air pollution generated from both roadway and aircraft traffic. Exposure to particulate air pollution increases risk of an asthma exacerbation ("asthma attack") and, consequently, the possibility of an emergency room or urgent care visit. Puget Sound communities near flight paths have higher baseline rates of asthma and higher rates of asthma-related emergency room visits. For this study, the investigators will test whether an indoor air quality intervention involving HEPA air filtration units can address disparities in indoor air pollution and asthma health in neighborhoods around the Seattle Tacoma (SeaTac) International airport. Previous studies have reported benefits to deploying HEPA filters in indoor spaces, including improved air quality, as well as, reduced frequency of asthma symptoms and exacerbations, which can lead to urgent care visits and hospitalizations. However, it is unknown whether a similar intervention will be effective for children with asthma exposed to airport-related pollution, specifically.

Researchers with the University of Washington, Department of Environmental and Occupational Health Sciences, with experience in pediatric airway health, air pollution monitoring, methods for improving air quality, and epidemiology will conduct this work. They will assess the effectiveness of an indoor air quality intervention in reducing exposure to indoor pollutants and avoiding asthma symptom flare-ups for children with asthma living near SeaTac International airport.

To conduct this study, a sample of children referred to the Public Health - Seattle & King County (PHSKC) Community Health Worker (CHW) Asthma Program and their caregivers will be recruited. Enrolled children and caregivers will be followed for 3 months in the AAA research study before they begin the CHW Asthma Education Program. Each will be randomized to an intervention group, which involves indoor air filtration using a HEPA air filter unit, or a control group, which receives an air filtration unit that may not reduce PM2.5 and ultrafine particulates, types of pollution specific to air and road traffic. About 60 families will participate in total across the two-year study period (January 2024 through June 2025).

The primary research questions assessed in this study are A) Does adding a HEPA filter intervention to the existing asthma education program improve asthma outcomes? and B) Is there an indoor air quality benefit to using an indoor HEPA filter in the homes impacted by aircraft-related air pollution?

Currently, the Community Health Worker (CHW) Asthma Program provides a range of educational services, a green cleaning kit, a HEPA vacuum and mattress encapsulation materials. It does not provide a portable HEPA filter for the participant's home bedroom. The purpose of this project is to assess the added benefit of adding the HEPA unit to future asthma education program interventions.

Caregivers will complete weekly questionnaires to track the occurrence of asthma symptoms, a marker of asthma exacerbations, and health care utilization for asthma. Air quality inside and outside the homes will be monitored. When the study is completed, the investigators will determine whether families in the intervention group had better air quality and improved asthma symptoms during the follow-up period. These findings will be disseminated to the community with the help of the CHWs.

Inclusion Criteria:

• Child is 6-12 years old with a health care provider-diagnosed asthma.
• Caregiver is comfortable in participating in all study activities in English (communicating with study staff by phone and completing online surveys).
• Caregiver is familiar with the child's daily asthma health.
• Residence within 10 miles of Seattle-Tacoma International Airport as determined by zip code
• Child resides in caregiver's home at least five nights a week on a regular basis and has no plans to move in the next three months.

Exclusion Criteria:

• Child has severe asthma at baseline. Severe asthma was defined in consultation with pediatric pulmonologists to be caregiver-reported asthma symptoms every day over the past 14 days and/or two or more inpatient hospitalizations for asthma in the past 12 months.
• Households were excluded if there were multiple individuals within the same household with asthma eligible for the King County CHW Asthma Program or had severe asthma.

De-identified information on indoor and outdoor air quality over the course of the study period will be shared through an open source publication. De-identified weekly symptom questionnaire will be shared, however identifiable participant information including age, gender/sex and home address will be redacted.

The study protocol, analysis plan is currently being prepared as an open-source publication to be shared with other researchers. The clinical study report and analytic code will be shared with researchers through open-source publication.

A data management plan is available through dmptool.org allowing researchers to identify and request data elements that are not available through open source mechanisms.

Participants and CHWs are masked to intervention status. The research team, including those who attend the home visit or manage and analyze data, are not masked.