As the July 2026 compliance deadline for the Hazardous Organic NESHAP (HON) Rule approaches, the chemical manufacturing industry finds itself at a crossroads. While some facilities have been granted temporary exemptions under new federal regulatory relief measures, others remain fully accountable to the stricter emissions standards established by the EPA. But the split in enforcement isn’t a pause, it’s a pressure test. The companies that treat this reprieve as a runway, not a loophole, will come out ahead.
Who’s Exempt from the HON Rule (for Now)?
On July 17, 2025, the President issued the “Regulatory Relief for Certain Stationary Sources to Promote American Chemical Manufacturing Security.” This order provides a two-year exemption from several EPA rules—including the HON Rule—for select facilities deemed essential to national security and economic resilience. While these exemptions offer breathing room, they also come with risk—regulatory reversals, community scrutiny, and technical debt can catch facilities off guard if they wait too long.
Key Facts:
- Covered Sectors: Chemical manufacturing facilities that produce critical components for semiconductors, defense systems, advanced manufacturing, and medical device sterilization.
- Exempt Companies Include:
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- Dow Chemical (LA, MI sites)
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- Formosa Plastics Corporation (TX, LA)
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- Westlake Corporation (LA)
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- Trinseo LLC (LA Glycol II Plant)
- Implementation: These facilities may continue following pre-2021 EPA standards until 2027.
Who Must Still Comply?
Facilities not named in the exemption list must stay the course on HON Rule implementation—and time is running out. These facilities face:
- Upgrades to or implementation of Continuous Emissions Monitoring Systems (CEMS) or Continuous Monitoring Systems (CMS)
- Enhanced leak detection and repair protocols
- More stringent recordkeeping and reporting requirements
- Tighter controls on emissions of hazardous air pollutants (HAPs)
Even for companies that are well underway in their compliance process, the complexity of the new standards requires technical expertise, robust data systems, and proactive strategy. We’ve seen the biggest challenges arise not from equipment, but from misaligned data systems and under-resourced teams.
How Forward-Looking Facilities Are Partnering with Montrose
Whether your facility is on the exemption list or fully subject to HON compliance, Montrose has the tools, teams, and expertise to support your path forward.
For Non-Exempt Facilities:
- CEMS/CMS Design & Deployment — for HON-regulated compounds like benzene, vinyl chloride, and other HAPs
- Site-Specific Monitoring Strategies — tailored to your compounds, operations, and infrastructure
- Permitting & Reporting Support — aligned with EPA and local air district requirements
- Real-Time Data Integration — via our Sensible EDP™ platform
For Exempt Facilities:
- Compliance Readiness — use this two-year window to plan ahead and pilot systems
- Pilot Monitoring Programs — already underway at several facilities to test CMS feasibility and reporting
- Scenario Planning — understand your fenceline concentrations now so you can coast into your compliance date with confidence, or if exemptions get overturned
- Community Relations Support — mitigating reputational risk with transparent data-sharing and community engagement
The Bottom Line
The HON Rule is here—and while some may get to delay, no one is off the hook forever. Whether you’re responding to immediate compliance obligations or preparing for the return of stricter standards, Montrose is already in the field, helping facilities pilot innovative monitoring approaches, deploy scalable systems, and stay ahead of shifting regulatory expectations.
Not sure how this affects your facility? Let’s map out your next steps before the window closes.
About the Authors
Jenna Granstra
Gulf Coast Operations Manager
Jenna has over a decade of experience managing large-scale air monitoring programs. She specializes in fenceline and community air monitoring, data analysis, and quality assurance.
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