With the advent of new sensors and technologies, smart devices that monitor the level of indoor air quality (IAQ) are increasingly available to create a healthy home environment. However, little has been studied regarding design principles for effective IAQ visualizations to help better understand and improve IAQ. We analyzed Amazon reviews of IAQ monitors and their design components for IAQ visualizations. Based on our findings, we created a conceptual framework to explain the process of facilitating an effective IAQ visualization with a proposed set of design considerations in each stage. The process includes helping users easily understand what is happing to IAQ (awareness), what it means to them (understanding), and what to do with the information (action), which results in two outcomes, knowledge gain and emotional relief. We hope our framework can help practitioners and researchers in designing eco-feedback system and beyond to advance both research and practice.