ASTM D8623-25

1.1 This practice presents a general strategy for using an analytic, odorant-prioritization-based approach for environmental odor assessment. It is based upon the premise that, while the composition of environmental odors detected by human receptors carries the potential for extreme complexity, simplification (that is, reduction of odorant field to smallest number of odor impactful compounds) typically occurs along the decreasing odor density gradient relative to the source (1-3).2 The odorant prioritization protocol (OPP) is a strategy that encourages initial identification of odor and focuses upon the minimum subset of odorous gases, which are sensory-detectable at the odor frontal boundary.

1.2 The OPP approach to environmental odor assessment is not presented as a replacement or substitute for established, quantitative Dynamic Dilution Olfactometry (DDO) methods (for example, Practices E679 and E1432), which form the current regulatory and enforcement basis for odor air quality impacts. Rather, this OPP approach is a voluntary, qualitative, and complementary assessment strategy for focused odor assessment and monitoring to support odor mitigation strategy development.

1.3 Units—The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.