Residential Cleaning of Indoor Air to Reduce Acute Exacerbations of COPD (CARE): A Pilot Study

Abstract

BACKGROUND AND AIM: Current studies of indoor air cleaning and respiratory disease generally use portable air-filtering devices that lack ventilation capabilities. We hypothesized that 8 weeks of air filtration and ventilation in the homes of COPD patients would improve functional status (measured by the St. George’s Respiratory Questionnaire; SGRQ) and decrease systemic inflammation (measured by serum high sensitivity C-reactive protein; hsCRP). METHODS: Our pilot randomized crossover trial in 2019 of 9 COPD patients (mean FEV1 of 47%; range: 20%-79%) used 2 window-mounted filtering/ventilation units (HEPAirX®) per home. Each participant was randomized to 8 weeks of residential air filtering/ventilation, followed by a 3-week washout period and a second 8 weeks of sham filtering (climate control without filtering or ventilation), or vice versa. Measurements of hsCRP and SGRQ were made before and after each 8 weeks of air-filtration/ventilation or sham, while step counts and indoor PM2.5 measurements were made continuously during each period. We compared hsCRP, SGRQ, PM2.5, and step count of the two groups (filter minus sham), subtracting baseline values from each. RESULTS:The baseline PM2.5 concentration averaged 3.4 µg/m3 (range: 1.0-11.4 µg/m3). The average PM2.5 concentration was 2.2 µg/m3 lower (95% CI: -8.7, 4.3 µg/m3) and the average hsCRP was 4.0 mg/L lower (95% CI: -17.7, 9.7) after 8 weeks of air filtration/ventilation compared to 8 weeks of sham filtering. Participants also walked 16.6 additional steps per hour (95% CI = -59.9, 93.2) and had a 1.0 unit improvement in SGRQ (95% CI: -9.7, 11.8) after air filtration/ventilation compared to sham. CONCLUSIONS:Although this study’s sample size was small, all of the non-statistically significant participant outcomes and pollutant changes associated with air filtration/ventilation were in the hypothesized direction. Though our initial findings are encouraging, a larger study is needed to test the respiratory health benefits of indoor air cleaning in the homes of patients with COPD. KEYWORDS: Indoor air pollution, Air filtration, Respiratory health effects, COPD, CRP, PM2.5