NYC-EJA’s Community Air Mapping Project for Environmental Justice (CAMP-EJ), a project led by six community-based organizations (CBOs) in the South Bronx and Brooklyn, empowered communities to address rampant air pollution through collecting, visualizing, and leveraging hyperlocal air quality data to improve air quality, public health, and community development. Collectively, the BMC, El Puente, THE POINT CDC, UPROSE, We Stay/Nos Quedamos, and Youth Ministries for Peace discovered that local facilities/expressways such as the Hunts Point “Toxic Triangle” & the Brooklyn-Queens Expressway are major PM2.5 polluters; air pollution in the South Bronx and Southside Williamsburg peaks in the morning and evening in response to higher traffic volumes (due to congestion and poor transportation infrastructure); and localized air quality measurements recorded pollution levels approx. 20X greater than those reported by the closest state-run monitor. CAMP-EJ’s recommendations include targeted investments/interventions in the South Bronx & Williamsburg to mitigate air pollution; city and state policies to reduce transportation sector pollution in EJ communities; and the prioritization of financial/technical support for hyperlocal air monitoring networks managed by EJ communities.