For too long, air pollution has been an invisible problem. That is until now. Innovative mobile sensor technologies hold tremendous potential for finding and measuring invisible pollutants that harm our health, disrupt business as usual, and change the climate. New sensing technologies and data analytics are exposing the presence of air pollution and connecting it back to sources and health impacts. As a result, policy makers, companies, and scientists can determine where communities are hit the hardest by air pollution – and tailor solutions that protect health and the environment.