In March 2024, the U.S. Environmental Protection Agency (EPA) finalized significant amendments to the Hazardous Organic NESHAP (HON) regulations, targeting the Synthetic Organic Chemical Manufacturing Industry (SOCMI). These changes are designed to reduce hazardous air pollutants and enhance public health protections, particularly in communities adjacent to industrial facilities.
With compliance deadlines approaching, it’s imperative for affected facilities to understand the new requirements and implement necessary measures. EDGE is committed to assisting clients in navigating these regulatory changes effectively. In addition to EDGE employees who have extensive experience with emissions measurement projects going back many years, EDGE has a strong working partnership with one of the world’s preeminent air emissions measurement experts.
Key Regulatory Changes
The updated HON regulations introduce several critical requirements and deadlines for existing sources:
- Fenceline Monitoring Start Date: Begin continuous monitoring for six key air toxics including ethylene oxide, benzene, and 1,3-butadiene, by July 15, 2026. One of two methods accepted: EPA Method 325 A/B (14-day passive diffusion) or Method 327 (24-hour canister sampling) is required based on which hazardous air pollutants are used, produced, or stored on-site.
- Monitoring Plan Submission: Submit a fenceline monitoring plan within 180 days of the effective date.
- Corrective Action Deadline: Implement required corrective actions for any monitoring exceedances by July 2027.
- Ethylene Oxide Standards: Existing facilities must comply with new ethylene oxide control requirements by July 2026.
- Additional Compliance Requirements include (Effective July 2027):
- Enhancements to source-focused regulations such as heat exchange systems, process vents, tanks, transfer operations, wastewater systems, and fugitive emissions. In some cases, compliance with the modified regulations may require a physical modification to the facility such as:
- Sites using flares for control may require additional monitoring infrastructure
- Reclassification of Group 1 and Group 2 tanks and vents may prompt revaluation and further controls
- Updates to floating roof tank standards may necessitate structural modifications
- Cooling tower sampling must now follow the Modified El Paso method with designated port locations
- Enhancements to source-focused regulations such as heat exchange systems, process vents, tanks, transfer operations, wastewater systems, and fugitive emissions. In some cases, compliance with the modified regulations may require a physical modification to the facility such as:
- Public Data Disclosure: Fenceline monitoring data will be made publicly available, and exceedances will trigger mandated investigation and remediation.
Anticipated Environmental and Health Benefits
According to the EPA, the HON amendments are expected to reduce hazardous air pollutants by more than 6,200 tons annually. While previous regulations addressed benzene emissions, this latest rulemaking introduces more stringent and targeted controls for ethylene oxide (EO), the pollutant at the center of many of the most substantial modifications. These changes reflect a stronger regulatory push to mitigate EO-related risks in fenceline communities. The rule also includes a projected 58% reduction in benzene emissions from tanks and equipment leaks. Together, these updates are expected to significantly improve public health outcomes and contribute to better air quality in surrounding communities.
EDGE’s Compliance Support Services
EDGE offers a full suite of services to support compliance efforts, from planning to implementation, including:
- HON Compliance Gap Assessments
- Fenceline Monitoring Program Design and Deployment
- Site-specific Monitoring Plan that accounts for offsite emission contributions
- Regulatory Strategy Development and Reporting Support
- Ongoing Monitoring and Corrective Action Planning
From evaluating current operations to implementing effective monitoring strategies, our experts specialize in helping clients meet new regulatory requirements efficiently and effectively. With respect to fenceline monitoring program design, EDGE does not propose standard or “canned” solutions; we develop custom solutions that are unique to your facility and goals. EDGE’s services are built to support compliance at every stage, ensuring your facility stays ahead of evolving air quality regulations. Contact our team today to learn how we can support your compliance goals.