Development of Test Equipment for Particulate Matter Filter Efficiency in Commercial Face Masks

Air pollution caused by particulate matter is a critical global concern. In Thailand, particulate matter levels frequently exceed the standard threshold, particularly in the northern region, where severe haze episodes are common. These levels were notably higher during the early and late parts of the year, particularly in the dry season. Selecting an appropriate face mask is crucial for respiratory protection. To ensure that the mask used provides adequate filtration efficiency, an accessible, cost-effective, and reliable method for performance assessment is essential. This quasi-experimental study developed testing equipment to evaluate the filtration efficiency of particulate matter under simulated breathing conditions, focusing on the performance of the materials used in face mask production. The primary objective of this study was to design and develop testing equipment for comparing the effectiveness of commercial face masks in filtering PM2.5 and PM10. The study also evaluated and compared the filtration efficiencies of three types of commercially available face masks-fabric masks, surgical masks, and KN95 masks-alongside a control scenario without a mask. Data were collected by analyzing the particulate matter across various size ranges. The calibration process employed a reference gravimetric method (NIOSH 0500) to ensure accuracy (±5% deviation) and sampling pump airflow rates of 1-2 L.min-1. The results revealed that the KN95 mask exhibited the highest filtration efficiency, with an average particle concentration of 0.489 mg.m- ³ (SD=0.067), followed by surgical masks (0.572 mg.m- ³, SD=0.127) and fabric masks (0.944 mg.m- ³, SD=0.167). Wearing a mask significantly reduced the particulate matter concentrations compared to not wearing a mask (p < 0.001). Addressing Thailand’s severe particulate pollution requires an accessible and cost-effective device for evaluating mask filtration efficiency. Although the equipment used in this study was not industrial-grade, it effectively simulated inhalation conditions. The developed equipment achieved laboratorygrade accuracy, making it suitable for rapid testing in low-resource settings. Its simplified design ensures compliance with the NIOSH Method 0500 standards