Indoor Bacterial Exposure in Sick Buildings and Associated Inflammatory Pathways in Humans: A Mini-Review

Indoor air quality (IAQ) and sick building syndrome (SBS) have long been public health concerns, which were further exacerbated by the COVID-19 pandemic. SBS is associated with inflammatory responses, and immune-related reactions play important roles in its pathogenesis. Bacteria play a significant role in deteriorating IAQ, especially in indoor environments. While bacteria in indoor environments are known stressors, their contribution to low-grade systemic inflammation and its impact on mental and physical well-being, including central nervous system effects, is a crucial aspect of SBS. This inflammatory response involves key cytokines like IL-1, IL-6, IFN-γ, and TNF-α, potentially leading to neuroendocrine changes, acute phase responses, and altered neural activity impacting behavior. This review provides a comprehensive overview of current research from an environmental health perspective and sheds light on the importance of bacterial concentration in line with inflammatory pathways in understanding SBS and highlights the need for effective strategies to mitigate bacterial contamination in indoor environments.