An association between short-term indoor exposure to fine particles (PM2.5) and acute respiratory effects has been reported. It is still unclear whether long-term indoor exposure to PM2.5 is associated with pulmonary events. This study recruited 1023 healthy adult homeworkers to conduct a prospective observational study from 2010 to 2021. Four repeated home visits per year were conducted for each participant to measure 24-hour PM2.5 and peak expiratory flow rate (PEFR) and to collect blood samples for absolute eosinophil count (AEC) and carcinoembryonic antigen (CEA) analysis. Additionally, a questionnaire related to personal characteristics, health status and home characteristics was conducted for each participant. The mixed-effects models showed a significant association of PM2.5 with increased CEA and AEC and decreased % predicted PEFR. No significant association between low-level PM2.5 exposure (10-year mean level < 10 μg/m3) and adverse pulmonary effects was observed. The present study concluded that long-term indoor exposure to PM2.5 at a concentration higher than 10 μg/m3 was associated with adverse pulmonary effects among healthy adult homeworkers.
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