Air Monitoring

Vapor Intrusion

Vapor Intrusion is defined as vapor phase migration of volatile organic (VOC’s) and/or inorganic compounds into indoor air spaces of occupied buildings from underlying contaminated ground water and/or soil. The resulting air quality problem from these vapors can pose a health risk to the occupants. Assessment of Vapor Intrusion sites typically includes a “multiple lines of evidence” sampling approach which involves sampling indoor and ambient air, soil gases, and groundwater sites.

Contaminants of Interest
Air Sampling Media and Analytical Standards by Regulatory Method
Types of Sampling – Indoor Air, Ambient Air, Soil Gas/Vapor
Technical Resources
Vapor Intrusion Image
Vapor Intrusion from Contaminated Soil & Water


Contaminants of Interest back to top
  • Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX) (additional information)
  • Volatile Organic Compounds (VOC’s) – polar, non-polar, chlorinated – Tetrachloroethylene (PCE –“Perc”), Trichloroethylene (TCE), Vinyl Chloride (VC), cis-1,2-Dichloroethene (DCE), Total Petroleum Hydrocarbons (TPH), Methyl tert-Butyl Ether (MTBE)  (additional information)
  • Polynuclear Aromatic Hydrocarbons (PAH’s) (additional information)
  • Polychlorinated Biphenyls (PCB’s) and Pesticides
  • Other common contaminants: Aldehydes, Ketones, and Acetone

Air Sampling Media and Analytical Standards by Regulatory Method back to top
Method Contaminants of Interest Sampling Media Analytical Standard
TO-3 BTEX, MTBE and TPH Tedlar Bags, Pumps EPA Toxic Organic Mix 2A
TO-4 A / TO-10 A Pesticides and PCB’s Polyurethane Foam Samplers (PUF)
Dioxin Sample Prep System
EPA Organochloride Pesticide mix
TO-5 / TO-11 Aldehydes and Ketones Midget Impinger EPA Aldehydes & Ketones
TO-13 A Low-Level olycyclic aromatic hydrocarbons Polyurethane Foam Sampler (PUF) / XAD-2 EPA TCL PAH mix
TO-14 A Non-polar VOC’s - TO-14 SUMMA Canister Sampling
TO-15 / 17 Polar and non-polar VOC’s,
select aldehydes
Solvent Desorption Tubes
Thermal Desorption Tubes
DNPH Tubes
Passive Sampling (radiello® & DSD)
ORBO-65P, 65M
TO-15 / 17 Standards
8021B Aromatic and Halogenated VOC’s Tedlar Bags, Pumps  Method 8021 Standards

Types of Sampling back to top
Indoor Air
For residential and commercial building owners alike, one concern is regarding the indoor air quality. Could the indoor air be polluted? If so, it is often difficult to determine the source because many factors could play a role in indoor air pollution besides vapor intrusion, such as background or pre-existing levels of pollutants from chemical use in the building – cleaning agents, paints and solvents, new carpeting and building materials, etc or from outdoor (ambient) air entering the building. If vapors do enter a building, the contaminant levels are usually very low and pose no immediate risk. Health problems associated with indoor vapor intrusion are commonly due to long-term exposure to low levels of these chemicals, which are proving to be dangerous to adults and especially to children. Typical sample collection times to assess this contamination are 24-hours for residential site sampling and 8 to 12 hours for commercial site sampling.

In the same context as Vapor Intrusion, Sick Building Syndrome (SBS) and Building Related Illness (BRI) are of concern. Sick Building Syndrome describes a situation where building occupants experience health related problems but no specific cause can be determined, while Building Related Illness associates the health related problems with a diagnosable illness that can be attributed directly to airborne contaminants. In both cases, the causes are typically associated with poor HVAC systems, off-gassing of building materials, lack of adequate air filtration, and mold.

Supelco provides the full range of air sampling products to address Indoor Vapor Intrusion , Sick Building Syndrome , and Building Related Illness.


Advantages of passive (diffusive) sampling over active methods in Indoor Air sampling:
  • Ease of application, silent operation 
  • No expensive equipment required
  • No leak testing required for soil gas
  • Lower reporting limits achievable compared to SUMMA canisters (i.e., 0.18 µg/m3 for benzene with a radiello® sampler over a 7-day sampling period as compared to 3.4 µg/m3 for 1-liter canister by standard TO-15 analysis)
  • Lower breakthrough/saturation for equivalent sample volumes
Ambient Air
In addition to indoor air pollution testing, it is necessary to perform ambient (outdoor) site testing to determine the chemical concentration from outside sources. Sample collection in this case is typically 24-hours. The same contaminants of interest are addressed for both indoor and ambient sampling. In order to determine the contribution of outdoor to indoor contaminants, the outdoor air concentration is subtracted from the indoor air concentration to exclude any outdoor sources from the vapor intrusion evaluation. This is necessary to exclude unrelated outdoor sources from the evaluation.
Soil Gas/Vapor
Soil is a vapor intrusion pollutant pathway and therefore is included in vapor intrusion studies. Soil gas monitoring provides a quick evaluation of waste site conditions, which can help identify the source of contamination, and its movement through the soil.

In order to sample soil gas, a hole must be driven into the ground by means of a drive rod and inserting a probe into this hole. The air sample is pulled from this probe into the collection device.

Supelco offers Tedlar® bags as a collection device for soil gas samples, and the vacuum pump to draw the vapor into the bag.
Tedlar bag

Soil Gas Micro-wells
Monitoring for VOC’s can also be achieved by inserting the radiello passive sampling device into the drive hole (see figure below). Sampling may be limited due to cartridge exposure to moisture or if airflow starved – less than 0.2 m/sec velocity.

Crawl Space Monitoring
radiello samplers provide an advantage over TO-17 and canisters due to their sensitivity and ability to achieve measurement of low concentrations of contaminants of interest.
Soil Gas: Micro-well
radiello for soil gas micro-well
Soil Gas: Crawl Space
radiello used for soil gas crawl space
(photos provided courtesy: DMS Environmental Services, LLC)

Technical Resources back to top
Review our Air Monitoring Literature page for useful selection guides and product information.
EPA Method References
EPA TO-3 (view document) EPA TO-10A(view document) EPA TO-14A (view document) EPA TO-17 (view document)
EPA TO-4A (view document) EPA TO-13A (view document) EPA TO-15 (view document) EPA 8021B (view document)
EPA TO-5 (view document)      


Related Agencies
Agency for Toxic Substances and Disease Registry (ATSDR / CDC)
CLU-IN – Technology Innovation Program
EPA Draft Guidance
  Johnson and Ettinger Model
  Brownfields Information
Interstate Technology and Regulatory Council (ITRC)
   Guideline (3.15mb PDF document)
   Vapor Intrusion Pathway: Investigative Approaches for Typical Scenarios (1.75mb PDF document)
National Brownfield Associations
The Mahfood Group, LLC
DMS Environmental Services