Pollution is disproportionately centered in disadvantaged communities at the mercy of toxic-spewing industries in their backyards. Inspired by the disinformation surrounding the 2010 BP oil disaster, Public Lab emerged to help Gulf communities undertake grassroots mapping efforts, using balloons and digital cameras to self-map over 100 miles of coastline. Their success led to a new global movement to develop affordable, community-based environmental monitoring tools, focusing on do-it-yourself, open-source tools, as well as training, education, and support, laying the groundwork for a more participatory approach to environmental justice. The Lab’s rapidly growing national and international network includes activists, educators, technologists, community organizers, residents of affected communities, hackers, hobbyists, environmental justice and conservation organizations, and institutionally-affiliated research scientists including physicists, geographers, optics and remote sensing experts, anthropologists and urban planners who contribute research, help others solve problems, build tools, and identify needs for future research via Public Lab’s online collaboration platform. Public Lab, the most effective open source tool platform we have seen, is a bold, visionary initiative that is helping empower communities around the world hold polluters accountable.