This paper describes inAir, a tool for sharing measurements and visualizations of indoor air quality within one’s social network. Poor indoor air quality is difficult for humans to detect through sight and smell alone and can contribute to the development of chronic diseases. Through a four-week long study of fourteen households as six groups, we found that inAir (1) increased awareness of, and reflection on air quality, (2) promoted behavioral changes that resulted in improved indoor air quality, and (3) demonstrated the persuasive power of sharing for furthering improvements to indoor air quality in terms of fostering new social awareness and behavior changes as well as strengthening social bonds and prompting collaborative efforts across social networks to improve human health and well being. Author Keywords Air quality, health, sensors, sustainability, persuasive technology, domestic technology, environment, iPhone. ACM Classification Keywords H5.m. Information interfaces and pr...