Ethylene Oxide Monitoring

Real-Time Ethylene Oxide Monitoring

In recent years, ethylene oxide (EtO) has emerged as a significant concern for regulatory bodies due to its classification as a carcinogenic air pollutant, posing long-term health risks to nearby populations.  In response, the US Environmental Protection Agency (EPA) enacted updated regulations in March 2024 under the Clean Air Act, aiming to reduce EtO emissions from commercial sterilizers by over 90%. This update revises the Air Toxics Rules and National Emissions Standards for Hazardous Air Pollutants (NESHAP), specifically for Hazardous Organic NESHAP (HON Rule).

Commercial sterilizers, crucial for disinfecting medical devices, are the primary sources of EtO emissions. To mitigate associated health risks, the new regulations mandate real-time EtO monitoring in workplaces to safeguard both workers and nearby residents. Additionally, facilities must report their emissions to the EPA. State and local agencies will also conduct ambient air monitoring around EtO-emitting sites to ensure compliance and evaluate potential health impacts. Due to its colorless and odorless nature at lower concentrations, many people remain unaware of EtO’s dangers.

Current monitoring methods, like off-line chromatographic techniques, have limitations related to sampling and storage. Real-time measurements often use laser absorption methods, which may not detect EtO at all risk levels, leading to a preference for computer modeling rather than direct measurements. Proton-transfer-reaction mass spectrometry (PTR-MS) has been occasionally used for EtO measurement, but is complicated by air interferences, as EtO shares the same protonated mass-to-charge ratio with acetaldehyde (45 Th, C₂H₄O•H⁺), a significantly more prevalent compound in the atmosphere.

To address these challenges, TOFWERK developed a method using our Vocus PTR Reactor in O₂⁺ adduct mode to detect EtO without interference from acetaldehyde or other compounds. Our technology can also detect a wide range of other air toxics, making it suitable for rapid (1Hz), long-term stationary monitoring, as well as robust mobile monitoring for fenceline detection, source apportionment, and leak spotting.