Evaluating the impact of air purifier intervention on particulate matter concentrations in a traditional Chinese medicine therapy room using multiple approaches

Traditional Chinese medicine (TCM) is a widely practiced holistic care system in East Asia. However, concerns have arisen regarding the health risks associated with smoke inhalation from moxibustion treatments for both patients and medical staff. Therefore, the aim of this study was to compare particulate matter (PM) concentrations in a TCM therapy room before and after installation of air purifiers. This study used multiple approaches to assess the impact of air filtration on PM levels and provided a more accurate evaluation. The first approach compared PM concentrations before and after implementation of air purifiers, which revealed significant reductions: PM₁ decreased by 16% to 72% (p < 0.01), PM_2.5 by 18% to 67% (p < 0.01), and PM₁₀ by13% to 49% (p < 0.05) at an air turnover rate (k_TO) of 5.6 h^-1. The second approach compared indoor/outdoor (I/O) PM before and after implementation of air filters. The I/O ratios of PM_2.5 and PM₁₀ revealed significant reductions by 46% and 35%, respectively. The third approach used a linear regression model to evaluate the effectiveness of the air purifiers, revealing that their use significantly reduced PM_2.5 and PM₁₀ concentrations by 7.00 and 12.48 µg/m³, respectively. Despite these reductions, the percent reduction in PM_2.5 was relatively low in this study, even with a moderate k_TO of 5.6 h^-1, comparing to other studies. This may be attributed to the high activity levels and crowded conditions in the therapy room, which limited the air purifiers' effectiveness. Vigorous mitigation measures, such as general ventilation with infiltration device, isolated room with local exhaust ventilation, are suggested to obtain the considerable decrease in PM.