As air quality regulations evolve, the demand for greater transparency and accountability continues to grow. Businesses are expected to provide accurate emissions data, demonstrate compliance, and proactively address environmental impacts—all while balancing operational efficiency and costs, and ensuring the protection of air quality for local communities.
With regulatory requirements becoming more stringent, it is critical to stay ahead of compliance deadlines and understand key changes. Here are some of the most significant air quality monitoring regulations to watch for in 2025 and how they may impact your business.
1. Ethylene Oxide: January Interim Registration Review Decision
Overview: Announced January 16, 2025, this decision includes potential updates to risk mitigation measures for ethylene oxide (EO or EtO) use, such as introducing stricter concentration limits, new engineering controls, and changes to personal protective equipment (PPE) requirements. The review also incorporates re-evaluating air emission standards under the Clean Air Act National Emission Standards for Hazardous Air Pollutants (NESHAP) to address risks to workers and the public.
What This Means for Businesses:
- Continuous indoor air monitoring will now use a 0.1 ppm (100 ppb) threshold, requiring visible results for workers within a 1-year timeframe.
- New PPE requirements mandate respirators for workers exposed to 1 ppm or higher (8-hour time-weighted average) and 5 ppm (15-minute short-term exposure limit).
- Companies involved in EtO sterilization must comply with revised concentration limits (600 mg/L for medical devices) and implement updated engineering controls, such as separating HVAC systems for processing areas.
- Increased worker monitoring, medical surveillance, and training will be required for workers exposed above the new action levels. This includes annual worker exposure data collection and compliance with updated safety protocols.
Montrose is your trusted partner in navigating the new EtO regulations. We help sterilization facilities assess current EtO usage and implement advanced monitoring systems to ensure compliance with updated action thresholds. Our expert team specializes in exposure mitigation strategies, including real-time environmental monitoring and data analysis, to reduce risks and enhance safety for workers and surrounding communities, all while prioritizing health and environmental stewardship.
2. PEPO NESHAP
Overview: In December 2024, the EPA proposed amendments to the Polyether Polyols Production NESHAP, targeting significant reductions in hazardous air pollutant (HAP) emissions, including approximately 14 tons per year (tpy) of Ethylene Oxide (EtO) emissions. These updates are part of the EPA’s broader initiative to protect public health and address environmental justice concerns.
What This Means for Businesses:
- Facilities must implement fenceline monitoring for EtO, measuring concentrations every 5 days via EPA Method 327.
- Compliance will require significant upgrades, including advanced emission controls and flare standards.
- Facilities must meet stricter emission limits, submit ongoing compliance reports, and adhere to phased deadlines beginning in 2025 to avoid penalties.
Montrose can support you in implementing reliable fenceline monitoring systems for EtO, ensuring continuous data collection to remain compliant with the EPA’s amendments. We provide end-to-end solutions, including monitoring plans, deployment/collection of canisters, sample analysis, instrument selection, installation, real-time data analysis, and ongoing reporting to meet the updated emission limits. Read more about PEPO NESHAP.
3. HON MACT
Overview: On March 28, 2024, the US EPA finalized updates to the NESHAP for the Synthetic Organic Chemical Manufacturing Industry (SOCMI) and Polymers and Resins Groups I & II. This rule aims to reduce emissions of ethylene oxide, chloroprene, ethylene dichloride, vinyl chloride, 1-3 butadiene and benzene, impacting over 200 facilities. Fenceline monitoring will be required by July 2026 of the rule’s publication for most facilities.
What This Means for Businesses:
- Companies must establish fenceline monitoring using EPA Methods 325A/B and 327.
- Immediate planning is essential to meet these stringent timelines and avoid penalties.
Montrose Environmental Group and Enthalpy Analytical provide end-to-end support to help facilities comply with the updated HON MACT requirements. Enthalpy holds Method 327 accreditation for both the PEPO and HON regulations where Method 327 is required. Together, we offer siting and implementation of EPA Methods 325A/B and 327, laboratory analysis, field services, and data aggregation. Sensible Environmental Data Platform (EDP) enhances compliance efforts by deploying real-time monitoring solutions for root cause analysis and corrective action, as well as developing site-specific monitoring plans to meet regulatory requirements effectively.
4. NSPS Subpart OOOOb
Overview: The EPA’s proposed New Source Performance Standard (NSPS) Subpart OOOOb regulation, announced in November 2022, updates performance standards for reducing methane and volatile organic compound (VOC) emissions from new, modified, and reconstructed oil and natural gas facilities. This rule includes many operational, reporting, and reporting requirements. From a monitoring perspective, key compliance deadlines include implementing initial and frequent routine leak detection surveys by 2025. The rule is always for using optical gas imaging (OGI) and Method 21 LDAR surveys, but it also provides the option of implementing continuous methane monitoring systems (CMMS).
What This Means for Businesses:
- By 2025, operators must have established their NSPS Subpart OOOOb-compliant monitoring program, implementing OGI, Method 21, or advanced monitoring technologies, such as CMMS.
- Operators choosing to implement CMMS or other advanced monitoring technologies optionally will need to obtain approval from the EPA.
- Companies will need to enhance internal leak tracking systems and prepare for increased recordkeeping and reporting requirements tied to emissions tracking and repair activities.
Montrose specializes in helping oil and gas operators meet the rigorous requirements of NSPS Subpart OOOOb. Our team offers expertise in implementing OGI, Method 21, and CMMS, based on what approach is the right fit for a site. We streamline compliance with the stringent monitoring requirements. We can also assist with baseline leak-free certifications, ensuring your facility is ready for CMMS deployment.
5. Colorado Regulation 7 Rulemaking Updates
Overview: Colorado’s Regulation 7 introduces updated air monitoring requirements for oil and gas operators conducting drilling operations in Colorado. Revised requirements are currently in draft form and are subject to change before finalization. As written, the rule impacts all new air monitoring plans for multi-well drilling facilities approved after a tentative date of May 1, 2025.
What This Means for Businesses:
- Operators must adhere to lower alert thresholds, stringent uptime requirements, and improved bump test protocols. These changes aim to align operational standards across all facilities.
- Air monitoring systems must support automated activation of summa canisters within 2,000 feet of residential buffer units (RBUs) and meet elevated data resolution standards to identify on-site issues more effectively.
Montrose Environmental Group develops Colorado Department of Public Health and Environment (CDPHE)-compliant air monitoring plans, provides advanced near real-time monitoring technologies, guides operators during planning meetings and hearings, and ensures seamless data aggregation, analysis, and integration into the Sensible Environmental Data Platform (EDP).
6. California Senate Bill 1137 (SB 1137) and Assembly Bill 218 (AB 218)
Overview: These bills prohibit new oil and gas production within 3,200 feet of sensitive receptors. Existing facilities must comply with phased engineering, operational, and monitoring requirements, with key deadlines approaching: a sensitive receptor inventory and map by July 1, 2025, compliance with PRC section 3282 requirements by July 1, 2026, leak detection and response plans by 2028, and fully implemented by 2030.
What This Means for Businesses:
- By July 1, 2025, operators must submit a sensitive receptor inventory and map.
- Enhanced LDAR and operational compliance are due by July 2026. Ensure a thorough understanding of those requirements this year.
Montrose can work with you today to create a sensitive receptor inventory and map, design, and implement enhanced LDAR programs to meet compliance requirements. Our team has extensive experience implementing and deploying continuous monitoring systems and creating detailed response plans to ensure seamless compliance.
7. U.S. EPA Methane Waste Emission Charge (WEC)
Overview: The Inflation Reduction Act required that the U.S. EPA establish the nation’s first methane fee, applicable to emissions exceeding allowances set for the oil and natural gas industry, which vary based on industry sector and product throughout. The fee was finalized in late 2024 and is calculated based on emissions reported under Subpart W of the U.S. EPE Greenhouse Gas Mandatory Reporting Rule (GHG MRR) and increases annually, starting at $900 per metric ton over the allowance in 2024 and rising to $1,500 per metric ton over the allowance by 2026.
What This Means for Businesses:
- Accurate emissions reporting is now tied directly to financial performance, with fees due annually starting in August 2025.
- Companies need robust data collection and emissions reduction strategies.
- Other large release events are included in the Subpart W emission inventory, meaning early detection and mitigation of unexpected emissions is critical to reducing WEC financial exposure.
Montrose and Sensible EDP offer integrated solutions to help businesses manage WEC exposure, from continuous methane monitoring for early detection of release events and boots-on-the-ground leak detection and quantification with our LDAR teams to data reporting and disclosure. With expert support and Sensible EDP, we ensure accurate emissions tracking and streamlined reporting to minimize financial impacts.
8. European Union Methane Regulation (EUMR)
Overview: This regulation will impact the global supply chain as it requires importers of natural gas, oil, and coal to disclose methane emissions along the value chain, including upstream sources. As a Monitoring, Reporting, and Verification (MRV) framework, the EUMR ensures that businesses track and report methane emissions transparently and verifiably, no matter where they are located. Methane intensity limits will take effect in 2030, but initial monitoring and reporting are required by August 2025.
What This Means for Businesses:
- Initial MRV reports are due by August 2025, with measurement-based programs required by February 2026 and 2027.
- Compliance pathways include OGMP 2.0 Gold Standard alignment with independent verification, national equivalency, producer-specific approvals.
The EUMR is groundbreaking in that it will impact energy producers worldwide and, like other new methane regulations, it is highly focused on measurement and detection to mitigation of information emissions. Montrose is here to help you navigate this transition. Sensible EDP can aggregate measurements using multiple techniques to better inform your MRV program. Our Montrose team also has experience leveraging measurement-informed data to develop effective mitigation strategies and has supported OGMP 2.0 projects worldwide. [Read more about Montrose and OGMP]
Need Regulatory Assistance?
Navigating the evolving regulatory landscape can be daunting and is essential for businesses to remain competitive and compliant. Montrose Environmental Group provides cutting-edge technology and custom monitoring solutions tailored to meet those challenges. With deep industry expertise, our project services teams empower clients with advanced monitoring dashboards, real-time data analysis tools, and the regulatory guidance you need to make critical business decisions. Whether it’s detecting fugitive emissions, implementing tailored HON MACT monitoring programs, mobile monitoring for ethylene oxide, or leveraging your data for compliance reporting, our services and technologies ensure facilities stay ahead of regulatory changes while protecting air quality for surrounding communities.
Are you affected by any of these or other monitoring regulations? Contact us today. We can help your business stay ahead of 2025’s monitoring regulatory requirements and beyond.