We live in a world of relentless change. Our cities are growing, we travel more, our technology is advancing. All the while, and with little thought or effort, we continue to inhale and exhale; around 20.000 times every day. Our environment matters. Our air matters. Yet every day, it gets polluted a little more. Be it from man-made machines, combustion engines or factories. Or from natural phenomena, like volcanos and wood fires. We, however, know very little about what we are breathing. But what if we could make sense of it all? We believe that distributed networks of small-scale environmental sensors can enable a fully-new approach to understand our environment, how it affects us and how we influence it. With our real-time data we can finally start to work on the underlying issues of environmental pollution. And we can develop strategies and best practices how to prevent it.