PEMEX H2S Release

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On October 10, 2024, at approximately 6:30 PM, the EPA was notified by the National Response Center of a hydrogen sulfide release from the PEMEX refinery in Deer Park, Texas. EPA response personnel were activated to conduct air monitoring in downwind communities and arrived on scene around midnight.

Hydrogen sulfide is highly flammable and toxic. According to the Potential Responsible Party (PRP), the release of material occurred from a pipe during scheduled maintenance. The release was verified to have been isolated and routed to the flare within 40 minutes of the incident. EPA air monitoring equipment did not detect hydrogen sulfide, and air monitoring results for sulfur dioxide were below levels of concern in the hours following the reported release. Residents are advised to be alert for safety orders from local authorities, which are responsible for issuing and amending shelter-in-place and other safety measures.

The EPA conducted community air monitoring using a MultiRAE Pro and ToxiRAE Pro. The MultiRAE Pro was equipped with a hydrogen sulfide sensor that detects levels as low as 0.1 parts per million (ppm). The incident-specific community action level for hydrogen sulfide is 0.33 ppm.

The ToxiRAE was equipped with a sulfur dioxide sensor that detects levels as low as 0.1 ppm. The incident-specific community action level for sulfur dioxide is 0.2 ppm.

Neither sulfur dioxide nor hydrogen sulfide were detected at levels above the action thresholds during the EPA’s community air monitoring efforts.

To explore the map and data points, use the “+” at the bottom right of the map to zoom in or the “-“ to zoom out. The map and data table below shows the EPA community air monitoring results.