Application of geographic mapping to community advocacy and environmental health policy-making

Maps of the geographic distribution of environmental hazards, adverse health outcomes, and related demographic and socioeconomic factors comprise an evidence base that community organizations can use to advocate with legislators and regulatory agencies for policies that address the community's environmental problems. Maps and data required to create maps may be available from state health departments and government environmental agencies. Data can also be collected by community organizations using simple environmental sampling equipment and surveys developed and conducted by community members. A variety of geographic information systems mapping software of varying complexity and cost is also available. Interpretation of maps of environmental exposure and health outcomes presents several challenges, including the ecological fallacy; artificiality of borders of census, political, and postal geographic units; the potential to gerrymander geographic areas to suit a particular hypothesis; and difficulty taking into account confounding factors for which data are not available. Developing a complementary relationship between professional and local knowledge can help counter these limitations. Professional expertise from public health agencies and academia can help communities navigate technical problems in collecting, analyzing, and interpreting data, while community residents can provide contextual and specific knowledge of sources and impacts of environmental hazards and mediating factors in their neighborhoods. A team of professionals and residents can present a many-faceted and compelling case to legislators, regulatory agencies, and the media to implement solutions to environmental problems of concern to the community.