Significance and Use
5.1 Some PFAS have been implicated in adverse human health impacts (4, 5, 6). Therefore, quantifying PFAS concentrations in indoor air is important for accurate and meaningful exposure analysis and risk assessments.
5.2 PFAS found in air can have a wide range of chemical characteristics that will impact sampling practice selection. For example, estimated vapor pressure values can vary by ten orders of magnitude, while estimated Henry’s Law constants can vary by five orders of magnitude (Table 1). This means that sampling and analytical methods that are appropriate for one PFAS compound may not be appropriate for other PFAS compounds. Hence, prior to sampling and selecting analytic methods for PFAS measurement in indoor air, it is critical to establish that the chosen PFAS sampling method(s) is appropriate for the target compound(s), the sampling location, and the environmental conditions.
5.3 The measurement of PFAS in indoor air is an active and growing research topic. Understanding of PFAS properties, sampling and analytic approaches and techniques is constantly evolving. This includes the determination of physical-chemical properties of many PFAS, which may not even have been measured experimentally or which have a wide range of experimentally determined properties (that is, 8:2 FTOH in Table 1). This guide describes methods that are in use at the time of publication.
5.4 PFAS in indoor air may come from a wide range of sources, including consumer products, building materials, food packaging, outdoor air, and other miscellaneous sources. PFAS is also commonly quantified in indoor dust. There are several methods that quantify these chemicals in solid and liquid media including, but not limited to Guide E3302, Test Method D7968, Test Method D7979, Test Method D8421, Test Method D8535, US EPA 533, and US EPA 537.1. US EPA OTM-45 quantifies some PFAS in the combined gas and particle phases of stationary sources, such as incinerator stack sampling.
5.5 This guide is applicable to sampling PFAS in indoor air (typically 15 °C to 30 °C, 20 % to 80 % relative humidity (RH)). While sources like soil vapor intrusion impact indoor air, the methods described here have not necessarily been applied or verified in other gaseous environments, such as soil pore vapor, stack samples, or under ambient outdoor air conditions (<10 °C, >30 °C, <20 % RH, >80 % RH). The methods and information presented here may apply or be compatible with determination of other PFAS or PFAS-like compounds, such as freons and greenhouse gases in other environments, including other collection and acquisition schemes, such as canister methods. However, the scope of this guide is limited to observationally reported PFAS in indoor air.
Scope
1.1 This guide describes methods for determining Per- and Polyfluoroalkyl Substances (PFAS) concentrations in indoor air.
1.2 This guide is focused on PFAS measurement technologies applicable to indoor air (including in vehicles and indoor workplaces) and other relevant air volumes such as, air in chambers, bags, or both. The described technologies were developed for indoor air; they may or may not be applicable to other types of air samples.
1.3 This guide describes available technologies and methods that can be used to measure indoor air PFAS concentrations in the gaseous or particulate phases, or both, in indoor air.
1.4 This guide describes each method and its advantages and limitations.
1.5 This guide does not attempt to differentiate between the effectiveness of the methods nor determine equivalence of the methods.
1.6 The sorbent-based sampling strategies addressed in this guide are for PFAS compounds with a molecular mass greater than 200 g mol-1 (1, 2, 3).2 Compounds less than 200 g mol-1, such as CF4, C2F6, or PFAS degradation products may require real-time analytical methods described in this guide or other methods that are not presented here.
1.7 Units—The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard.
1.8 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.
1.9 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.
