The Breathe Easy Study: Impacts of Ventilation Improvements on IAQ and Adult Asthma in 40 Existing Homes in Chicago, IL

Abstract

BACKGROUND AND AIM: This paper presents preliminary results of the Breathe Easy Project, which as designed to improve indoor air quality (IAQ) and asthma-related health outcomes by installing residential mechanical ventilation systems in forty existing homes in Chicago, IL. Each home had at least one self-reported adult resident with asthma and received one of three types of ventilation systems half-way through the study: exhaust-only system, central-fan-integrated-supply (CFIS) system, or balanced system with an energy recovery ventilator (ERV). METHODS: We conducted quarterly field measurements to monitor indoor and outdoor pollutants, including size-resolved particles (0.3-10 µm), ozone (O3), nitrogen dioxide (NO2), carbon dioxide (CO2), carbon monoxide (CO), and formaldehyde (HCHO). Monthly asthma control test (ACT) surveys were administered for each participant throughout the study. Wilcoxon signed-rank tests were used to evaluate the impacts of ventilation system retrofits on IAQ, indoor/outdoor (I/O) ratio, and ACT score. Chi-square tests for independence and multiple logistic regression were used to analyze associations between IAQ, asthma severity, and baseline characteristics of participants and homes. RESULTS:Indoor pollutant concentrations and I/O ratios were significantly lower after ventilation system retrofits for indoor concentrations of HCHO, CO2, PM1.0, PM2.5, and PM10, and I/O ratios of CO2, NO2, PM1.0, and PM2.5 (P 0.05). There was a small but significant increase in average ACT score of 1.04 across the entire study population after the ventilation system retrofits (P 0.001). Based on association analysis of the pre-intervention period, higher NO2 concentrations were associated with increased odds of poorly controlled asthma, with crude odds ratios (OR) (95% CI) of 2.8 (1.2−6.4). Also, Black participants showed OR (95% CI) of 5.7 (1.3−25.9) for poorly controlled asthma compared to White participants. CONCLUSIONS:The results can potentially provide information on the influence of exposure for many air toxics and will furnish an opportunity to evaluate exposure models for these compounds. KEYWORDS: Air pollution, asthma, exposures, occupational epidemiology