Vapor Intrusion Assessment Calculator

Evaluate the vapor intrusion pathway using Johnson-Ettinger model attenuation factors and EPA screening levels.

Sub-slab soil gas (µg/m³)

Groundwater concentration (µg/L)

Henry's law constant (dimensionless)

Building footprint (m²)

Mixing height (m)

Crack fraction of slab

Air exchange rate (ACH)

Indoor air screening level (µg/m³)

Tab to move between fields

J&E attenuation factor

Total indoor air (µg/m³)

0.22

Risk ratio (J&E model)

0.71

Soil gas from GW (µg/m³)11,400

Indoor air from sub-slab (µg/m³)0

Indoor air from GW (µg/m³)0.22

Exceeds screening (0/1)0

Risk ratio (EPA generic)1,112.9

How to Use This Calculator

Enter sub-slab soil gas concentration (µg/m³) from vapor probes or building surveys.
Set groundwater concentration (µg/L) and Henry's Law constant for your contaminant.
Enter building footprint (m²) and mixing height (m) for indoor air dilution modeling.
Review calculated indoor air concentrations from both sub-slab and groundwater pathways.
Compare results to indoor air screening levels to determine if mitigation is required.

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