Outdoor air pollution is a serious health hazard, with high levels of smog and haze making the world news. What is rarely reported, is that indoor air quality can be up to 30 times worse, with microscopic health threats like mites, formaldehyde, detergents and bacterial often going unnoticed. Air purifiers provide the solution but, unaware of the problem, people fail to protect their families effectively. To make this invisible problem visible, together with artist Niles Volker we built the Breathing Wall: a living installation made of 192 bags and 384 fans. Breathing in real-time to the surrounding environment, the Wall also revealed shocking educational health facts about poor indoor air quality.