The Clean Air Act Watch List: An Enforcement and Compliance Natural Experiment

I exploit a natural experiment created by the US Environmental Protection Agency's (EPA) Clean Air Act watch list. The watch list was designed as a monthly tracking system for internal use at EPA, but its existence and the identities of facilities on some watch lists were publicly revealed beginning in late 2011. Variation created by the watch list and its public release allow me to identify the compliance impact of listing on the watch list and the compliance impact of the public release of the watch list. Results suggest that the average violation probability fell between 10 and 15 percentage points as a result of initial listing on the watch list and between 15 and 23 percentage points as a result of the public release of the watch list. The paper's findings inform the discussion regarding the effectiveness of traditional and information-based enforcement tools.