Urban Sensor Hack #5 - AirCasting, featuring Master Makers Tim Dye, Michael Heimbinder, Iem Heng, and Raymond Yap -- aka the AirCasting crew -- who guide us through the step-by-step process for building our own air quality monitor, discuss the challenges involved in achieving accurate measurements, and detail their work with grassroots groups and schools to conduct environmental monitoring and advance STEAM education. For more info, check out the Urban Sensor Hacks page, and join the Urban Sensor Hacks Google+ Community, and share what you're doing with sensors too.