Nuevo León's Secretariat of Environment has asked federal regulator ASEA for an urgent technical inspection of the Ing. Héctor R. Lara Sosa refinery in Cadereyta Jiménez, after reports of bad odors in several parts of the Monterrey metropolitan area. The request asks officials to determine whether an unusual event or technical failure occurred between Aug. 23 and 26.
The state is not announcing a finding yet. It is asking for an on-site review, operational records, and verifiable measurements so the next read-through is based on plant data rather than reports from the street.
Why it matters
For operators around the metro, this moves the issue into a defined environmental-oversight process. The requested review covers sulfur-recovery plants, gas-treatment units, flares, venting systems, and emissions-control equipment — the systems most relevant to understanding what happened during the reported period.
The request also asks for sampling of sulfur dioxide, hydrogen sulfide, mercaptans, ammonia, and volatile organic compounds. That gives the eventual discussion a specific technical checklist, rather than leaving it at the level of odor complaints.
The other side
Neither the state bulletin nor El Horizonte says ASEA has confirmed the inspection or that the refinery caused the odors. The state is asking the federal agency to establish whether an atypical event could be related.
What to watch
Watch for ASEA's response, the refinery's Aug. 23–26 operating logs, and the measurement results. Nuevo León says it will analyze the findings and make the information public after receiving the federal review.
- Where: Cadereyta Jiménez refinery; odor reports across metro Monterrey
- Who: Nuevo León Environment Secretariat, ASEA, Pemex refinery
- Period under review: Aug. 23–26, 2026
- Requested checks: plant systems, emissions measurements, operating logs
- Money or jobs: not stated in either source