Air pollution and pulmonary health: Effects of short-term indoor air quality intervention with portable air purifier

Abstract

Introduction: Chronic ambient air pollution exposure is known to adversely affect health outcomes. While it will take a long time to improve the outdoor air quality in China, using an indoor air purifier can produce immediate reductions in indoor air pollution. This study aims to investigate the impacts of overnight use of an indoor air purifier on cardiopulmonary health. Methods: Seventy-two healthy non-smoking students were recruited into a randomized, double-blind crossover study. Between November to December 2015, each subject received 2 overnight 13-19-hour interventions consisting of a True filtration and a Sham filtration (purifiers with or without a HEPA filter and an active carbon filter) with a 2-week washout period in-between. Cardiopulmonary health parameters were assessed through spirometry for lung function, impulse oscillometry (IOS) for airway resistance and elastance, Vicorder for arterial stiffness, and biomarkers of inflammation, oxidative stress, and hemostasis. Results: The median outdoor PM2.5 level during the study was 47 µg/m3 (Q1-Q3 range: 30.7 µg/m3, 70.0 µg/m3). A preliminary analysis was done using a mixed effect linear model with the subject as the random effect. Pulmonary health impacts of True and Sham filtrations were compared as reflected in the change of each biomarker from “before” to “after” intervention. Compared to Sham filtration, True filtration was shown to significantly lower pulmonary impedance (Z5) by 0.16 (P=0.048) and airway resistance R10 by 0.138 (P=0.043). No significant changes in other impulse oscillometry measurements (R5-R20, X5, Fres), exhaled nitric oxide, and spirometry parameters (including FEV1, FVC, FEV1/FVC, and PEF) were observed. Conclusion: Under a moderate level of ambient air pollution, overnight use of an air purifier significantly reduces pulmonary impedance and airway resistance at 10Hz. Further analysis of the targeted molecular biomarkers is underway.