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#Itrc indoor air sampling breathing zone height how to#

predictive models allowed by the agency (some states have their own predictive models).

default attenuation factors allowed by the oversight agency.

tables prepared by the oversight agency.

Screening levels can be obtained from three primary sources: Screening levels are also different for different types of receptors, such as primarily residential versus commercial or industrial buildings. Screening levels vary from state to state and, in some cases, within the state itself. In order to determine what concentrations are of concern and what analytical methods are required, screening levels must be known. Note that 24.0 is a standard conversion factor based on the ideal gas law at 20☌ and 1 atm. Example conversion calculations for benzene (molecular weight = 78) at 20☌ (68☏) are: Most laboratories report air data in µg/m 3 and ppbv.

Locate an easy-to-use unit conversion spreadsheet available at many web sites, such as NJDEP's VI guidance, Table 6-1, p.

Instruct the laboratory as to the units and detection levels in which it should report the data.

Prior to scoping a field program and conducting field work, performing the following tasks will help to prevent unit errors: Converting between units (for example, mg/L to mg/m 3, percent to ppmv) is also a common source of error. The units are not equivalent, and the conversion depends primarily upon the molecular weight of the compound.

Unit ErrorsĪ common error is assuming that ppbv is equivalent to mg/L or that ppmv is equivalent to mg/L. Practitioners commonly make errors with soil vapor programs and soil vapor data in three general areas: units, screening or target levels, and project goals/objectives. Vapors and VI are an unfamiliar territory for many practitioners in this field (regulators, stakeholders, consultants, subcontractors). Important Considerations in VI Investigations

In addition, Table G-6 provides the advantages and disadvantages of various investigative strategies. Analytical methods and related issues are discussed after the sampling methods.Ī summary of the various quantitative options used to evaluate the VI pathway is provided in a matrix in Table G-5, Matrix of recommendations for various quantitative options to evaluate VI. The methods presented in this appendix are not arranged in a particular order of preference. References are provided for additional information regarding each of the tools.

#Itrc indoor air sampling breathing zone height how to#

Each section explains how to use the tools and when they are appropriate. In many cases, the methods and tools described in this section are applicable to both petroleum and nonpetroleum vapor investigations. As an example, indoor air and subslab data, commonly collected for assessing the VI pathway for chlorinated compounds, are often not the preferred approach for PHCs since indoor and ambient sources of PHCs are so common. Hence, sampling locations and some procedures can differ from those used at sites with chlorinated hydrocarbon contamination. PHCs, unlike CVOCs (with the exception of vinyl chloride), readily degrade in the presence of O 2 during migration through the vadose zone, which lowers the potential risk by VI. This updated toolbox contains sampling and analysis issues and procedures specific to VI sites, with new sections for sites where PHCs are the COCs. The investigative toolbox in this guidance is an updated version of the toolbox located in Appendix D in the ITRC guidance document entitled Vapor Intrusion Pathway: A Practical Guideline ( ITRC 2007).

discussing the applicable field instruments with site counterparts.

developing a list of appropriate questions for your lab.

selecting the best analytical method for the required analysis.

understanding the importance of sample collection processes to ensure quality data.

Specifically this appendix will help with the following tasks: This information will help you select the techniques that will best meet the data objectives. This section describes various sampling and analysis methods available for vapor intrusion investigations. Investigation Methods and Analysis Toolbox Investigation Methods and Analysis Toolbox