The effect of particulate matter reduction by indoor air filter use on respiratory symptoms and lung function

Abstract

Background: Exposure to particulate matter (PM) is a key public health issue, but effective intervention has not yet been established. A systematic literature review and meta-analysis has been conducted to assess the relationship between the use of air filters, one of the most-studied interventions, and respiratory outcomes in patients with chronic respiratory disease. Methods: Studies that included data on PM level changes and respiratory symptoms or lung function in patients with respiratory diseases were eligible for inclusion. Chronic respiratory diseases included asthma, COPD, bronchiectasis and interstitial lung disease. Effect estimates were quantified separately using the random-effects model. Results: Among 1522 related articles, a total of 18 effect estimates from seven studies were included. Of seven eligible studies, six were randomized controlled trials, and one was a randomized cross-over study. The study population was pediatric asthmatics (n=6) or adult COPD patients (n=1). In all enrolled studies, air filter use reduced indoor PM2.5 significantly and the model yielded a pooled estimated of absolute difference in PM2.5 of 11.45 µg/m3 (95% confidence interval [CI]: 16.01-6.88 µg/m3). Air filter use improved predicted forced expiratory volume in one second (FEV1) significantly with 3.60% (95% CI: 0.29-6.90%, a random effect model). Air filter use was not associated with a significant change in respiratory symptoms (odds ratio: 0.82; 95% CI: 0.62-1.08). Conclusion: Study evidence indicates a statistically significant association between the use air filters and increased lung function with significant reduction of indoor PM2.5.