Air and water pollution are well-known concerns in cities throughout the world. However, communities often lack practical tools to measure and record pollution levels, and thus are often powerless to motivate policy change or government action. Current government-funded pollution monitors are sparsely located, and many large national and local governments fail to disclose this environmental data in areas where pollution is most prevalent. We have been developing very low-cost, ultra low-power environmental sensors for air, soil, and water, that enable communities to easily sample their environment and upload data to their mobile phone and an online map. This not only empowers communities to enact new policies, but also serves as a public resource for city health services, traffic control, and general urban design.