As the Latin expression puts it, Quis custodiet ipsos custodes? This is a phrase from the Roman poet Juvenal, which is literally translated as “Who will guard the guards themselves?” 

Well, according to a new report from the Office of the Inspector General, the Environmental Protection Agency’s (EPA) internal watchdog, not the petroleum refineries:

Oversight by the EPA and delegated authorities has not ensured that all refineries that exceed the action level reduce their benzene concentrations at their fencelines. For example, from January 2018 to September 2021, 13 of the 18 refineries we reviewed had benzene concentrations above the action level in 20 or more weeks after the initial exceedance. Many of these refineries are located near communities with potential environmental justice concerns. Furthermore, three of these 13 refineries had not reduced their annual average concentration to the action level or below. These refineries may not have accurately identified the root cause of their exceedances or taken appropriate corrective actions. Despite the existence of potential issues, the EPA and delegated authorities took limited formal enforcement-related actions at refineries under the benzene fenceline monitoring regulations.

We identified barriers that could prevent the EPA and delegated authorities from determining whether refineries exceed the action level. For example, some refineries have EPA-approved monitoring plans that rely solely on modeling—instead of on additional monitoring, as required by EPA regulations—to estimate contributions to benzene concentrations from emissions sources not covered by the monitoring regulations. Modeling could overestimate benzene contributions from these other sources and mask whether a refinery has exceeded the action level. Also, some refineries did not submit all the required data to the EPA and thus may not have reported high concentrations that could have pushed them over the action level. Specifically, based on our analysis of the data from January 2018 to September 2021, five refineries failed to report monitoring data for at least two weeks. If the EPA and delegated authorities cannot identify exceedances of the action level, then they cannot ensure that refineries take corrective action as required. This could result in communities being exposed to higher benzene concentrations and associated health risks than if appropriate corrective actions were taken.

Read the full report here.