August 5, 2024— 

Effective monitoring of EtO levels in occupational settings, environmental surroundings, and industrial processes is crucial to ensure compliance with safety and environmental regulations. This blog explores current and upcoming regulations surrounding EtO emissions, best practices surrounding monitoring and managing EtO risk, as well as techniques and technologies available to companies facing challenges in EtO emissions monitoring. Montrose and Sensible EDP have collaborated with Thermo Fisher Scientific to offer easy to deploy solutions which deliver low detection limits to serve your project applications.

Regulations

Current and Upcoming

Federal, state, and local agencies have implemented stricter regulations surrounding EtO emissions, including the recently promulgated National Emission Standards for Hazardous Air Pollutants (NESHAP) and the Proposed Interim Decision (PID) intended to reduce the risk to workers regarding the use of EtO. While not a full or exhaustive list, the regulations noted below are key drivers enacted by the regulatory agencies to help protect the health of our communities.

NESHAP: In May of 2024 EPA updated the National Emission Standards for Hazardous Air Pollutants (NESHAP) for ethylene oxide commercial sterilization and fumigation operations, as mandated by section 112 of the Clean Air Act. The standards aim to safeguard public health by compelling existing and new major sources to limit emissions to the maximum achievable control technology (MACT) level, while existing and new area sources must control emissions using generally available control technology (GACT).

PS-19: As part of the NESHAP, EPA established a performance specification (PS) for CEMS monitoring EtO on stacks and control device inlets. PS-19 outlines procedures for initial installation and acceptance testing. Key elements include specifying instrument accuracy, defining measurement locations, and establishing initial quality assurance procedures and requirements. Procedures for calibration drift, standard additions, dynamic spiking, calibration verification, and interference assessment all provide guidance on installing an EtO CEMS that meets the NESHAP requirements.

Procedure 7: As part of the NESHAP, EPA established ongoing requirements for CEMS monitoring EtO. Procedure 7 outlines quality assurance procedures including daily calibration drift and quarterly audits which may include, Relative Accuracy Test Audits (RATA), Relative Accuracy Audits (RAA), cylinder gas audits (CGA) and Dynamic Spiking Audits (DSA).

SCAQMD Rule 1405: This rule aims to significantly reduce EtO regulated. For large medical sterilization facilities sources, emissions must be reduced by 99.99%, Alternatively, a facility can comply with an alternative concentration limit of 10 parts per billion. Continuous Emission Monitoring Systems (CEMS) are mandated for large sources, along with fence-line monitoring, which ceases once CEMS is operational. Fenceline monitoring involves either canister collection and TO-15 / TO-15A analysis every six days or continuous real-time monitoring. If ethylene oxide concentrations exceed set thresholds in real-time monitoring, canister samples must be collected for further analysis.

Proposed Interim Decision: In April 2023, EPA released the proposed interim decision (PID) for EtO. The PID proposes measures that would mitigate EtO's risk to human health and focuses on worker and community exposure. The proposed action threshold was 10 parts per billion of EtO in indoor air. A number of facility operational changes such as all in one sterilization and EtO usage reductions were also proposed. The final interim decision is expected to be released in fall of 2024.

Best Practices & Monitoring Techniques

While there has been great progress to ensure the safe handling of EtO, companies that make and work with ethylene are using what they’ve learned to improve best practices while striving to minimize emissions. The best practices noted below establish some common guidelines for managing EtO emissions as well as the technologies available to measure and monitor collected samples.

Best Practices for Consideration

Selection of Monitoring Methods: Choose appropriate monitoring methods based on the specific application, such as direct-reading instruments for real-time monitoring, passive or active sampling for personal exposure assessment, or continuous monitoring systems for fixed locations. Consider factors such as detection limits, accuracy, and sampling duration when selecting monitoring equipment.

Calibration and Maintenance: Regularly calibrate monitoring equipment according to manufacturer recommendations to ensure accuracy and reliability of measurements. Perform routine maintenance and quality checks to verify instrument performance and address any issues promptly.

Sampling Strategy: Develop a comprehensive sampling or monitoring strategy that includes sampling locations, frequencies, and durations based on the results of the program objectives and regulatory requirements. Consider factors such as proximity to EtO sources, worker activities, ventilation rates, and process operational activities when designing sampling plans.

Data Interpretation and Analysis: Analyze monitoring data regularly to identify trends, deviations from baseline levels, or exceedances of regulatory limits. Investigate any unusual or elevated EtO concentrations promptly and take corrective actions as necessary, such as implementing engineering controls or modifying work practices.

Available Monitoring Technologies

Expertise along with technology can provide comprehensive solutions for navigating the evolving regulatory landscape of EtO emissions and ensure the highest level of safety and operational efficiency. Primary forms of monitoring technologies may include:

Continuous Monitoring Systems: Continuous monitoring systems are installed in fixed locations to continuously measure EtO concentrations in stacks, control device inlets, ambient air or within industrial facilities. These systems utilize optically enhanced fourier-transform infrared spectroscopy (FTIR).

Direct-Reading Instruments: Portable gas detectors equipped with electrochemical sensors or photoionization detectors (PID) can provide real-time measurements of EtO levels in workplace environments. These instruments offer immediate feedback on gas concentrations, enabling prompt action if elevated levels are detected. These instruments generally have high detection limits and will not be useful for the proposed indoor air regulations.

Passive Sampling: Passive samplers, such as diffusive tubes or badges, are often used for personal exposure monitoring. These devices collect EtO from the air over a specified period, typically 8 hours to a week, which can then be analyzed in a laboratory to determine average exposure levels.

Active Sampling: Active sampling methods involve actively drawing air through sampling media such as sorbent tubes or canisters using pumps. This method allows for higher sample volumes to be collected, enhancing sensitivity and accuracy in measuring EtO concentrations. Samples collected can be analyzed using gas chromatography (GC) coupled with mass spectrometry (MS) for quantification. These systems are generally not easy to use and require much operation and maintenance support

Sensible EDP EtO Solution

• Sensible EDP, (a Montrose Environmental Company) offers integrated, proven, and easy to deploy solutions, which deliver low detection limits to serve your project applications. Our ethylene oxide monitoring solution has been installed and operating for years supporting stack and indoor air quality monitoring programs.
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• Montrose's Sensible EDP and Thermo Fisher Scientific have collaborated to provide an all-encompassing solution for organizations facing challenges in EtO emissions monitoring, testing, and regulatory compliance. By integrating Montrose’s extensive project services expertise, Sensible EDP’s comprehensive data platform, and the Thermo Fisher’s cutting-edge StarBoostTM Optically Enhanced MAX-iAQ™ OE-FTIR Gas Analyzer, clients gain access to a powerful combination that streamlines their efforts to meet stringent regulations and maintain safe operations.

MAX-iAQ™ OE-FTIR Continuous Monitoring System: The MAX-iAQTM is a fully automated 20-channel ambient air monitoring solution for low-level detection of EtO, even in high humidity environments. It can quantify EtO to a detection limit of 1 ppb using advanced StarBoost™ technology while maintaining short cycle times. It is also designed to operate as a continuous monitor with little-to-no user interaction.

MAX-EMS-10™ OE-FTIR Continuous Monitoring System: The EMS-10™ Continuous Emissions Monitoring System (CEMS) is a fully automated 4-channel stack emission monitoring system designed specifically for hot wet samples. The EMS-10 system can quantify ethylene oxide down to a detection limit of compounds down to a detection limit of 1 ppb while maintaining short cycle times, using advanced OE-FTIR spectral analysis and Thermo Scientific™ StarBoost™ Technology. This makes the EMS-10 an ideal alternative to traditional gas chromatograph-based systems that are typically slower, less sensitive and more costly to maintain.

MAX-iR EtO Mobile CART: The cart offers robust mobile monitoring of Ethylene Oxide and detection limit of Limit <1 ppb. It uses single channel, real-time gas analysis and is validated for ambient air and hot/wet (stack) emissions applications. In addition, it is compliant with US EPA Method 320 and ASTM D6348.

Proton Transfer Reaction Time-of-Flight Mass Spectrometer (PTR-TOF-MS) Mobile Laboratory: With Sensible EDP's PTR-TOF-MS (PTR Van) provides on-the-go, mobile laboratory solutions for real-time detection of organic and inorganic compounds (including ethylene oxide) at parts per trillion (ppt) levels. The PTR mobile solution provides precise measurements to accurately identify and measure fugitive emissions, indoor air quality or map a city or community for background levels of ethylene oxide.

The teams at Sensible EDP and Thermo Fischer Scientific offer expertise in air quality measurement and the most innovative, emerging technologies in ambient, fence-line, and community air monitoring. With a collection of services encompassing air quality monitoring, toxicology and industrial health, our customers receive full end-to-end service with a partner they can trust.