Indoor environments dominate human exposure to air pollutants, yet indoor air quality (IAQ) monitoring and control are often fragmented across proprietary platforms and isolated devices. This study presents an open, production-ready framework that integrates low-cost sensors, open-source IoT infrastructure, and building control devices into a unified IAQ management system. Environmental data are collected by edge devices and managed through a web-based interface offering real-time visualization, historical analysis, and network-wide mapping. Beyond monitoring, the framework enables interoperable, data-driven control strategies, such as filtration activation during pollution events. By coupling real-time sensor data with continuous mass-balance modelling, the system provides actionable indoor/outdoor exposure indicators to inform automated control. The results demonstrate that open and interoperable architectures can bridge monitoring and mitigation, supporting scalable, transparent, and energy-efficient IAQ management across residential, commercial, institutional, and research settings.