Vapor Intrusion Survey

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Sampling Procedures

One of the most significant findings is that a majority of states do not have written guidance on how to collect samples for vapor intrusion from the various media (i.e., soil, groundwater, soil gas). A majority of states do not have specific laboratory methods for analyzing vapor samples. Mobile laboratories are being utilized for soil gas and some indoor air sampling. Seasonal variability is considered in most VI evaluations. Seventy-three (73%) of the respondents recommend or require subslab samples; however, only 17% have written guidance on how to collect the sample, and how many samples to collect. For indoor air sampling, about 50% use a 24-hour sampling period, and about 70% use stainless steel evacuated canisters for sampling indoors.

Click on each question to view results.

56-61. Does your agency have written guidance on the collection of the following:

56. Soil gas samples
57. Soil gas guidance: other agencies referenced by respondents.
58. Flux chamber samples
59. Flux chamber guidance: other agencies referenced by respondents.
60. Indoor air samples
61. Indoor air guidance: other agencies referenced by respondents.



62-64. Does your agency have a specific laboratory method required for the analysis of:

62. Soil gas samples
63. Flux chamber samples
64. Indoor air samples



65-70. If the response to any of questions 62-64 is 'Yes', identify the analytical method:

65. Soil gas samples
  • TO-15

  • TO-17

  • 8021

  • 8260

  • Other method (see question 66)

    • 66. Other soil gas analytical methods indicated by respondents.

    67. Flux chamber samples
  • TO-15

  • TO-17

  • 8021

  • 8260

  • Other method (see question 68)

    • 68. Other flux chamber analytical methods indicated by respondents.

    69. Indoor air samples
  • TO-15

  • TO-17

  • 8021

  • 8260

  • Other method (see question 70)

    • 70. Other indoor air analytical methods indicated by respondents.



    71-73. Does your agency consider seasonal variability when evaluating:

    71. Soil gas data
    72. Flux chamber data
    73. Indoor air data



    74-76. Does your agency permit mobile laboratories to be utilized for the analysis of:

    74. Soil gas data
    75. Flux chamber data
    76. Indoor air data



    77. Does your agency recommend/require sampling of soil gas beneath buildings?

    78. Does your agency have guidance on how many soil gas samples to collect near/under a structure?

    79. Does your agency limit how far away (horizontally) a soil gas sample can be collected from a structure when evaluating the vapor intrusion pathway?

    80. Does your agency allow the use of flux chambers for assessing the vapor intrusion pathway?

    81. Does your agency have guidance on how many flux measurements to conduct at an existing structure or undeveloped lot?

    82. When interpreting flux chamber data, does your agency: (Check all that apply.)
    a. Calculate a room concentration from flux value?
    b. Allow for room exchanges in this calculation? (If so, please indicate how many below.)
    c. Use a slab factor if no slab exists?
    d. Allow spatial averaging of fluxes from more than one location?
    e. Unknown.



    83. Does your agency require certification for laboratories used specifically for indoor air analyses?

    84. What specific sampling devices does your agency accept or recommend for indoor air samples?
  • Tedlar bags

  • Stainless steel canisters

  • Sorbent tubes

  • Others? (see question 85)

  • Unknown


    • 85. Other sampling devices than those given in question 84.

    86. Does your agency specify or recommend the number of indoor air samples to be collected per sampling event?

    87. What time period does your agency prefer the indoor air sample collected over?
  • Instantaneous (or grab) sample

  • 1 hour or less

  • 1-23 hours

  • 24 hours

  • Unknown




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