By Steve Wing

On June 14, 2010, ASTM International (formerly the American Society for Testing and Materials) issued E 2600-10, Standard Guide for Vapor Encroachment Screening on Property Involved in Real Estate Transactions. This document revises and supersedes ASTM E 2600-08, Standard Practice for Assessment of Vapor Intrusion into Structures on Property Involved in Real Estate Transactions, issued on March 3, 2008.¹

Read more about vapor intrusion…

The increase in regulatory oversight at vapor intrusion sites nationwide, as well as recent publication of Federal and local vapor intrusion guidance documents and screening levels has led to a need for reliable air phase (indoor air and sub-slab/soil vapor) data at extremely low concentrations. This paper will explore and discuss the importance of media cleanliness and certification to achieve typical low level data quality objectives.

Several potential pathways of media contamination will be examined, including: canisters, flow controllers/critical orifice assemblies, vacuum gauges, and canister pressurization/fill stations in the laboratory.

Several contamination situations will be explored and quantified. The resulting data will be used to support laboratory and field sampling best practice recommendations.

Read the complete air sampling media cleanliness case study… (Acrobat PDF)

Diffusive sampling has been a popular approach for the evaluation of workplace exposures to airborne contaminants, such as volatile organic compounds (VOCs) for some time. Typically, these “badge-type” samplers (e.g., 3M, SKC) have been used to evaluate exposures in the high part per billion (ppb) to part per million (ppm) range over an 8-hour period. A popular option, these samplers are easy to use, small in size and don’t require a sampling pump.

This approach involves the passive collection of an analyte on a solid sorbent via adsorption or chemical reaction. The sampling rate (e.g., diffusive uptake rate) is a function of the diffusive coefficient, which is compound and sorbent specific, and the geometry of the sampler used. Other factors that affect performance include temperature, pressure, humidity, air velocity and transient changes in contaminant concentrations. Samples are chemically desorbed and analyzed by gas chromatography with flame ionization detection (GC/FID) or by other appropriate instrumentation.

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