Improvement of indoor air quality and health effects in COPD patients in a heavy industrial area.

Indoor particulate matter (PM) and nitrogen dioxide (NO2) have been associated with adverse health effects in patients with chronic obstructive pulmonary disease (COPD); however, the effects of indoor carbon monoxide (CO), total volatile organic compounds (TVOCs), and sulfur dioxide (SO2) levels on health outcomes in COPD remain unclear. For decomposing gaseous pollutants, photocatalytic oxidation (PCO) is regarded as a promising approach in chamber studies; however, no field study has evaluated its effects in patients with COPD. This study aimed to evaluate the associations between indoor air pollutants and cardiopulmonary endpoints, as well as the effects of PCO/PCO + filters on these outcomes in patients with COPD. A double-blind crossover study was conducted among 61 patients with COPD. We measured indoor air pollutants using real-time monitoring equipment and collected cardiopulmonary endpoints before and after intervention. This study is the first to demonstrate significant positive associations between indoor PM2.5 and CO levels and diastolic blood pressure (DBP), as well as between indoor NO2 and symptom scores and modified Medical Research Council Dyspnea Scale in patients with COPD (p < 0.05), with percent changes of 0.038 %, 0.350 %, 0.113 %, and 0.750 %, respectively. After PCO + filters intervention, we found significant reductions in indoor PM2.5 (-28.8 %), CO (-42.1 %), TVOCs (-21.5 %), and SO2 (-94.9 %), and was accompanied by a significant 2.9 % reduction in DBP. These findings provide insight into the potential cardiopulmonary benefits of improving indoor air quality through PCO + filters intervention in patients with COPD, highlighting the need for mitigation strategies in highly polluted areas.