Toward Effective Monitoring of Diffuse VOC Emissions: A Critical Discussion and Review of the Applications of EN 17628:2022

Highlights: What are the main findings? EN 17628:2022 introduces a technical framework for monitoring diffuse VOC emissions, outlining five techniques for detection, localization, and quantification. The analysis highlights the strengths and limitations of the described methodologies in the characterization of complex emissions from industrial sites. What is the implication of the main finding? An accurate selection of monitoring techniques is crucial for improving the reliability of emission flux estimates. The integration of complementary techniques enables a more robust analysis of emissions, addressing the complexity of diffuse sources in an industrial context The estimation and characterization of diffuse emissions of volatile organic compounds (VOCs) is a crucial issue for industry and environmental regulators. Compared to channelled ones, diffuse emissions derive from complex (non-point) sources, such as wastewater treatment plants, storage tanks, and process unit components. Such sources are typically influenced by dynamic factors such as operational activities and weather conditions. Therefore, this complexity makes the localization and quantification of diffuse VOC emissions a crucial challenge from a technical and regulatory perspective. Recently, the technical standard EN 17628:2022 has been published, which provides a framework to address this issue, proposing five different techniques for the localization, identification, and quantification of diffuse emissions. Nevertheless, while it represents a step forward in this field, the standard shows some shortcomings for a proper implementation, potentially causing divergent interpretations of the guidelines. The accuracy of the measurements is highly dependent on the configuration and morphology of the site, but especially on the meteorological data implemented to calculate the emitted flux. In addition, these techniques, despite being well-established, are particularly complex from both a technical–scientific and logistical–economic point of view. An emerging method, Quantitative Optical Gas Imaging (QOGI) appears to theoretically overcome some issues, but requires further studies to ensure accurate and reproducible quantification of emissions. This review aims to highlight the advantages, disadvantages, and potential developments of the various techniques described in the standard for the characterization of diffuse VOC emissions in the industrial sector.