AirCasting is an open-source, end-to-end solution for collecting, displaying, and sharing health and environmental data using your smartphone. The platform consists of wearable sensors that detect changes in your environment and physiology, including a palm-sized air quality monitor called the AirBeam, the AirCasting Android app, the AirCasting website, and wearable LED accessories. By documenting and leveraging health and environmental data to inform personal decision-making and public policy, the AirCasting platform empowers citizen scientists and changemakers.