Concentration of PM2.5 and PM10 Particulate Matter in Various Indoor Environments: A Literature Review

Indoor exposure to particulate matter (PM2.5 and PM10) remains a significant public health problem, especially in high-traffic areas, where outdoor pollution, building characteristics, and user activity jointly influence indoor air quality. This study aims to synthesise and compare the effectiveness of key technical solutions to reduce indoor PM concentrations in different types of buildings. A comprehensive review and comparative analysis of published experimental and field studies were conducted, covering residential, educational, office, medical, sports, and heritage buildings. The interventions evaluated included mechanical ventilation and filtration systems, portable HEPA air cleaners, integrated building envelope solutions, airflow optimisation strategies, and selected auxiliary technologies. Reported performance metrics such as baseline indoor and outdoor PM concentrations, air exchange rate (ACH), filter class, clean air delivery rate (CADR), and percentage reduction were systematically analysed. The results indicate that mechanical filtration, particularly high-efficiency HVAC (Heating Ventilation and Air-Conditioning) systems and HEPA filters, provide the most reliable and repeatable reductions in PM2.5 and PM10, especially under controlled airflow and recirculation conditions. Integrated approaches that combine airtight building envelopes, mechanical ventilation, and local air purification achieved the highest overall effectiveness. The findings confirm that successful PM mitigation requires context-specific multicomponent strategies tailored to building type, outdoor pollution load, occupancy, and ventilation design.