Asthma Intervention With Residential Ventilation and Air Cleaner (AIRVAC) Study

This study will evaluate the long-term effectiveness of energy recovery ventilators (ERVs) and portable air cleaners (PACs) in reducing indoor concentrations of air pollutants and mold, and improving health outcomes among children and adults with asthma. The study design will utilize a double-blind, placebo-controlled, 4-arm, parallel-group, randomized controlled trial with 1-year observation and 1-year intervention periods. Eligible children (n ≥ 40) and adults (n ≥ 40) with asthma from 80 households will be recruited from an applicant pool for RTNTX home retrofit programs. Participants will be randomized to receive one of four different interventions midway through the study: (1) ERV, (2) sham/placebo ERV, (3) PAC, or (4) sham/placebo PAC. All participants and field research team will be blinded to whether participants receive the active or sham/placebo intervention. ERVs will be equipped with minimum efficiency reporting value (MERV) 13 filters to capture particulate matter from incoming outdoor air, while sham/placebo ERVs will be modified to operate only in recirculation mode (no outdoor air ventilation). PACs will have high efficiency particulate air (HEPA) and carbon filters, whereas sham/placebo PACs will have the HEPA and carbon filters removed, leaving only the pre-filters. These objectives will be achieved through a combination of (i) baseline housing condition assessments for characterizing housing-related factors such as housing conditions, health and safety issues, and basic building performance, that may contribute to asthma exacerbations and affect the installation of ERVs, (ii) field measurements of indoor air pollutants (i.e., PM, VOCs, NO2, CO, and CO2) and mold levels (both air and surface samples), and (iii) comprehensive asthma outcome assessments via participant-reported health surveys for asthma control, asthma-related quality of life, stress, and sleep quality. Asthma control will be tracked monthly using the Asthma Control Test (ACT) for adults and the Childhood Asthma Control Test (C-ACT) for children. Quality of life, stress, and sleep will be assessed during home visits using validated instruments, including the 36-Item Short Form Health Survey (SF-36) and the Pediatric Quality of Life Inventory (PedsQL) for quality of life; the Perceived Stress Scale (PSS) and the Patient-Reported Outcomes Measurement Information System (PROMIS) Pediatric Stress measure for stress; and PROMIS Adult and Pediatric Sleep measures for sleep quality.

Results from the research are expected to identify practical and effective commercially available systems that can (1) investigate the long-term effects of different mechanisms between ERVs and PACs on IAQ, mold, and health outcomes in asthmatic children and adults; (2) provide novel data on associations among asthma outcomes, indoor air pollution and mold exposure, and housing-related factors; (3) evaluate the long-term health benefits, including reduced direct costs for asthma and estimated mortality attributable to improved IAQ and mold, versus the total costs of interventions; and (4) investigate the utility of low-cost sensors for assessing housing-related hazards and epidemiology studies, and for providing actionable information on IAQ and mold levels to patients and their physicians.

• Energy Recovery Ventilator (Device), also known as ERV: A mechanical ventilation system that exchanges stale indoor air with fresh outdoor air while transferring heat and moisture between the incoming and outgoing air streams
• Portable Air Cleaner (Device), also known as PAC, HEPA Air Cleaner, Residential Air Cleaner, Room Air Cleaner, Air Purifier: A standalone home device that filters indoor air to remove particulate matter, allergens, and other pollutants
• Energy Recovery Ventilator (Sham) (Device): A home-installed ERV unit that operates in recirculation mode only, providing no fresh air exchange or heat/moisture transfer, serving as a placebo for study purposes.
• Portable Air Cleaner (Sham) (Device): A portable air cleaner that appears to operate like an active unit but does not contain a HEPA filter and does not clean the air, serving as a placebo for study purposes

Primary outcomes

• Pulmonary Function (Spirometry) [Baseline; 6 months; 18 months; 24 months]: Pulmonary function will be assessed using an EasyOne Air spirometer. The primary parameters measured include Forced Expiratory Volume in 1 second (FEV₁), Forced Vital Capacity (FVC), and the FEV₁/FVC ratio.
• Asthma Control Test Score [From enrollment to the end of intervention at 1 month (24 months in total)]: Asthma Control Test (ACT) for adults and Childhood Asthma Control Test (C-ACT) for children every month throughout the 2-year study. ACT score range: 5-25; higher scores indicate better asthma control. C-ACT score range: 0-27; higher scores indicate better asthma control.

Secondary outcomes

• Asthma-Related Quality Of Life (Adults) [Baseline; 6 months; 18 months; 24 months]: 36-Item Short Form Health Survey (SF-36) for adult participants. SF-36 score range: 0-100; higher scores indicate better health status.
• Asthma-Related Quality Of Life (Children) [Baseline; 6 months; 18 months; 24 months]: Pediatric Quality of Life Inventory (PedsQL) for child participants. PedsQL score range: 0-100; higher scores indicate better quality of life.
• Stress Levels [Baseline; 6 months; 18 months; 24 months]: Perceived Stress Scale (PSS) for adults and Perceived Stress Scale for Children (PSS-C) for children. PSS score range: 0-40; higher scores indicate worse perceived stress. PSS-C score range: 0-39; higher scores indicate worse perceived stress.
• Sleep Quality [Baseline; 6 months; 18 months; 24 months]: PROMIS Sleep Disturbance Survey for both adult and child participants. PROMIS Sleep Disturbance score range: 20-80 (mean = 50, SD = 10); higher scores indicate worse sleep disturbance.

Sex: All, ages: 5 Years to any

Inclusion Criteria:

* Individuals with physician-diagnosed asthma, including both adults and children aged 5-17
* Homeowners living in the DFW metropolitan area, TX

Exclusion Criteria:

* Participants living in homes with any smokers

• Stephens B, Kang I, Jagota K, Elfessi Z, Karpen N, Farhoodi S, Heidarinejad M, Rubinstein I. Study protocol for a 1-year, randomized, single-blind, parallel group trial of stand-alone indoor air filtration in the homes of US military Veterans with moderate to severe COPD in metropolitan Chicago. Trials. 2025 Jun 4;26(1):196. doi: 10.1186/s13063-025-08880-0. PMID 40468409
• Kang I, McCreery A, Azimi P, Gramigna A, Baca G, Hayes W, Crowder T, Scheu R, Evens A, Stephens B. Impacts of residential indoor air quality and environmental risk factors on adult asthma-related health outcomes in Chicago, IL. J Expo Sci Environ Epidemiol. 2023 May;33(3):358-367. doi: 10.1038/s41370-022-00503-z. Epub 2022 Nov 30. PMID 36450925
• Kang I, McCreery A, Azimi P, Gramigna A, Baca G, Abromitis K, Wang M, Zeng Y, Scheu R, Crowder T, Evens A, Stephens B. Indoor air quality impacts of residential mechanical ventilation system retrofits in existing homes in Chicago, IL. Sci Total Environ. 2022 Jan 15;804:150129. doi: 10.1016/j.scitotenv.2021.150129. Epub 2021 Sep 8. PMID 34798726

• Insung Kang, Ph.D., Principal investigator, The University of Texas at Arlington