Journal of Applied Chemical Science International

Air pollution has become a major environmental and public health concern, particularly in urban areas where rapid industrialization, traffic emissions, and population density contribute to elevated levels of airborne contaminants. In educational settings, such as secondary schools, poor air quality can adversely affect the health and cognitive performance of students, making the assessment of indoor and outdoor pollutants essential for risk management. This study comprehensively assessed the levels of particulate matter concentrations in indoor and outdoor air at some secondary schools in Port Harcourt Local Government Area (LGA), Rivers State. The study focused on measuring levels of particulate matter (PM₁, PM_2.5, PM₄, PM₇, PM₁₀) and evaluating seasonal variations. Sample collection across nine secondary schools covered a period of twelve months (twice per term during academic session), covering the dry and wet seasons. Particulate matter concentrations were obtained using a calibrated handheld Aerocet Particle Mass Counter 531S. The results demonstrated higher indoor particulate matter (PM) concentrations compared to outdoors across schools. Indoor PM₁ ranged from 3.9–8.1 µg/m³ versus 2.90–7.45 µg/m³ outdoors, while PM_2.5 was 18.5–24.5 µg/m³ indoors compared to 13.3–20.07 µg/m³ outdoors. The coarser particles (PM₄, PM₇, and PM₁₀) also exhibited higher concentrations indoors compared to outdoors with location PCSN having the highest average concentration indoor for PM₁₀ at 153.9±118.5 µg/m³. Overall, particulate levels tend to be higher indoors than outdoors, especially for larger particles, although some outdoor values remain comparably high in certain locations. Overall, particulate matter concentrations were consistently higher during the dry season than wet season across all schools and particulate sizes, with larger particles exhibiting more pronounced increase. Generally, the concentrations of particulate matter for all nine schools were within permissible limit from PM₁-PM₁₀ (both indoor and outdoor) except location PCSN school which exceeded the permissible limit at PM₁₀ for indoor. The study highlighted significant indoor particulate accumulation, across schools within Port Harcourt L.G A. It was recommended that schools authorities should implement improved ventilation systems, limit indoor combustion sources, and establish regular cleaning and dust control practices to reduce indoor particulate matter.