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Resilience and Motivation. Learning can build resilience, because-by definition-learning requires you to realize you don't already know it all and encourages you to try something new and fill in gaps of information.There are still a lot of people who still do not know about Vapor Intrusion. And in the spirit of educating, learning, and growing. For those in and out of the field. Click on the video below. Feel free to share! #growthmindset #vaporintrusion #vaporpin ... See MoreSee Less
One of our own, Kyle Chilcote, has been going through some Physical Therapy for some ATFL (Anterior Talo-Fibular Ligament) Damage recently. He's taken advantage of his unfortunate situation by learning more about SEO (Search Engine Optimization)! Kyle says, "It has really helped me in understanding the frustrations that all SEO specialists have. Especially when it comes to all of the things that should be thought of prior to a web page coming into existence." He has suggested brushing up on SEO terms is very helpful. Especially, "For anyone else who also has the urge to make sure that an employee or vendor is set up for success prior to a project." If anyone is interested in what he was using to learn. He was following along with the Simplilearn free youtube videos! The playlist link is below.#learning #searchengineoptimization #success #vaporintrusion #vaporpin ... See MoreSee Less
Join us February 13th for a band on workshop at Ecosearch srl. See you soon🔹 Vi avevamo promesso delle novità, vi avevamo promesso che quest’anno tornavamo ad organizzare Workshop nella nostra azienda e così abbiamo fatto.🆕 Il 13 febbraio si terrà nella nostra sede un Workshop VaporPin. Nel nostro sito potete scaricare il programma e il modulo di adesione, qui di seguito il link ⬇️: partecipazione è gratuita, dovete solo compilare il modulo di adesione e mettere su Google Maps “EcoSearch” per raggiungerci.Vi aspettiamo numerosi, non vediamo l’ora di accogliervi nella nostra azienda!!Vapor Pin#VaporIntrusion #Remediation #SitiContaminati ... See MoreSee Less
NEW - Tygon Connectors!The Vapor Pin® Kit is designed to make your use of our products a success each time. However, one item was previously not included - the connector to match the barb fitting to the sample train. From this point forward, our kits will include Tygon connectors to bridge the distance between your sampling train and the Vapor Pin® Sampling Device. You may also purchase a bag of Tygon connectors separately or in 5 foot lengths. ... See MoreSee Less
Vapor Pin is at Ferrara.
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I'm thrilled to share with you the program of Remtech Europe 2021. This important environmental conference is made of 23 sessions fully ONLINE. Any session is completely FREE.To follow any session you have to register in our website with a valid email. To reserve your seat, receive the presentations in pdf and receive your Certificate of Attendance of the session you will attend, you have to register in the Google form of each session. In each form you would find also the detailed program and beginning and end in different time zones. Reserve your seat today!SESSION 1 (Organized by JRC-European Commission) From policy talking to industry actions: Zero Pollution for Soil Mon 20 SEPTEMBER 09:00 – 13.00 CEST 2 (Organized by US Army Corps of Engineers) TRAINING COURSE - PFAS: characterization, environmental impact, remediation strategies Mon 20 SEPTEMBER 14.30 – 19.00 CEST 3 Sustainable management of contaminated sites Mon 20 SEPTEMBER 14.30 – 16.30 CEST 4 Waste tailings and acid mine drainage: challenges for Mining Sites Mon 20 SEPTEMBER 17.00 – 19.00 CEST 5 Bioremediation and phytoremediation in agricultural, industrial, and military sites Tue 21 SEPTEMBER 09.00 – 11.00 CEST 6 Oil and hydrocarbons impacted sites Tue 21 SEPTEMBER 11.30 – 13.30 CEST 7 HRSC, High Resolution Site Characterization Tue 21 SEPTEMBER 11.30 – 13.30 CEST 8 (Organized by ASTM) TRAINING COURSE - ASTM STANDARDS: PFAS, Sediment and Climate Resilience Tue 21 SEPTEMBER 14.30 – 19.00 CEST 9 Innovative, digital and smart characterization techniques tools Tue 21 SEPTEMBER 14.30 – 16.30 CEST 10 Circular Economy: how to apply it in the context of the next Generation EU Tue 21 SEPTEMBER 17.00 – 19.00 CEST 11 Soil remediation: can we deal in a sustainable way? Wed 22 SEPTEMBER 09.00 – 11.00 CEST 12 DNAPL and chlorinated compounds: optimize the process to achieve the target Wed 22 SEPTEMBER 11.30 – 13.30 CEST 13 (Organized by SERDP-ESTCP) TRAINING COURSE - Current Approaches for Vapor Intrusion Site Investigation and Mitigation Wed 22 SEPTEMBER 14.30 – 19.00 CEST 14 (Organized by Ramboll) TRAINING COURSE - Sustainability assessment as a tool for a more sustainable and resilient remediation of soils, groundwater and sediments Wed 22 SEPTEMBER 14.30 – 16.30 CEST 15 PFAS, remediating the forever chemical Wed 22 SEPTEMBER 17.00 – 19.00 CEST 16 Microplastics and sediments: two main threats for ports and coastal areas Thu 23 SEPTEMBER 09.00 – 11.00 CEST 17 Sustainathon Thu 23 SEPTEMBER 14.00 – Fri 24 SEPTEMBER 14:00 CEST 18 Aeriforms and vapor intrusion: measures and models Thu 23 SEPTEMBER 11.30 – 13.30 CEST 19 Groundwater remediation in difficult conditions Thu 23 SEPTEMBER 11.30 – 13.30 CEST 20 (Organized by AESAS) TRAINING COURSE - State of the art of contaminated sites in Brazil Thu 23 SEPTEMBER 14.30 – 19.00 CEST 21 River environment: managing impacts from different sources Fri 24 SEPTEMBER 09.00 – 11.00 CEST 22 Wastewater and sewer sludge, handling the last link in the chain Fri 24 SEPTEMBER 11:30 – 13.30 CEST 23 TRAINING COURSE: Wastewater control and seawater quality: it is possible to do it acting differently? Fri 25 SEPTEMBER 14.30 – 19.00 CEST free to share to your colleagues or to any contacts that you think he/she may be interested. REMEMBER THAT THE CONFERENCE IS FREE, NO FEES. JOIN US !See you online!Laurie A. ChilcoteRemtech Europe Ambassador ... See MoreSee Less
Vapor Pin is at RemTech Expo.
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Decontamination and Decommissioning of Warehouses - Gela Industrial Site. - Author: Mariangela Venco (ENI Rewind) RemTech Expo ... See MoreSee Less
We are excited to announce our Brazil Patent BR 11 2018 004186-6 has been granted!#remediation #vaporintrusion #contaminatedsites #vaporpin #vi #coxcolvin #patent #Brazil ... See MoreSee Less

Main Content

Vapor Intrusion – The Four Horsemen: Benzene, Chloroform, Naphthalene, and Trichloroethene

In vapor intrusion, “background” is contamination in indoor air that came from outdoor (ambient) air or from interior sources, such as cleaning products, paints, and plastics. Owners of facilities associated with soil or groundwater contamination might be obliged to mitigate vapors at their own and at surrounding properties, and if they can’t distinguish between vapor intrusion and background, they might be paying for someone else’s problem. Worse, most vapor-mitigation systems prevent soil gas from entering the building, and if vapors are from background, the system won’t help.

EPA’s 2011 report on background contamination shows some interesting trends. The authors compiled the results of indoor-air samples collected from residences with no known or suspected vapor intrusion. As seen in Figure 4 from this report, below, benzene, chloroform, and TCE were present in 91%, 68%, and 43% of residences, respectively. Naphthalene does not appear on this graph, because its molecular weight is somewhere between those of volatile organic compounds (VOCs) and a semi-volatile organic compounds (SVOCs), and was often excluded from VOC sampling. But the toxicity and volatility of naphthalene, together with its widespread occurrence in background, have earned it a place on the list of vapor-intrusion compounds, and on the list of problem compounds. According to the Montana Department of Environmental Quality’s 2012 background investigation, naphthalene was detected in 40 out of 50 residences with no known vapor intrusion.


Figure from USEPA 2011, Background Indoor Air Concentrations of Volatile Organic Compounds in North American Residences, EPA 530-R-10-001.

Where do these compounds come from? Benzene is the B in BTEX – benzene, toluene, ethylbenzene, and xylenes, all of which are widely associated with gasoline and other fuels. Benzene poses the greatest problem of the BTEX compounds, since the other three have comparatively low toxicity. Benzene is also the base for countless manufactured chemicals, so of course, benzene is commonly detected in the subsurface, and is a common constituent of concern for vapor intrusion. Benzene is also ubiquitous in ambient air, especially in metropolitan areas, due to vehicular traffic and fuels. Benzene also can be expected in background in buildings with attached garages, due to its presence in vehicular gas tanks, gas-storage cans, and lawn equipment.

Chloroform is normally present in chlorinated water, and not surprisingly, chlorine is common in indoor air. But tap water is not the only source, and perhaps, not the most important source of chlorine in indoor air. At vapor-intrusion conferences, speakers often report high levels of chloroform in indoor air, but when I ask them where they think it came from, they rarely have an answer. However, a number of recent investigations have focused on sewer gas, and found that dry plumbing traps, breached toilet-wax rings, loose pipe fittings, and other conditions often allow sewer gas to enter buildings, bringing chlorine with it. Whatever the source of chloroform in background, Massachusetts’ 2008 Technical Update – Residential Typical Indoor Air Concentrations indicates a median concentration for chloroform of 1.9 ug/m3. The residential VISL in Ohio is 1.2 ug/m3. Good luck with that.

At one time, naphthalene was the main ingredient in mothballs, but it’s been replaced by chlorinated compounds to reduce the risk of fire. Naphthalene is typically associated with coal and the heavier petroleum oils. Naphthalene has the lowest residential indoor-air VISL of the big four compounds, at 0.83 micrograms per cubic meter (0.83 ug/m3), using Ohio standards of 10-5 cancer risk, and a hazard index of 1 for non-carcinogenic compounds. Consequently, the lab’s reporting level for naphthalene, even using 6-liter “Summa” cans, might exceed indoor air screening levels, unless results are reported to Method Detection Levels (MDLs). Reporting to MDLs generally results in the detection of numerous additional compounds, making data validation and interpretation more complicated and costly. The additional information seldom changes the final assessment, but if ya’ gotta, ya’ gotta.

And, finally, TCE rounds out the list of four bad players. We’ve discussed TCE a number of times, including in the August 2017 edition of Focus on the Environment, but in case you haven’t heard, TCE drives most of the vapor-intrusion work in recent years, due to concerns over fetal heart defects. Much or most of the concern with vapor intrusion is tied to the risk of cancer, which generally develops over years or decades. Although, as discussed in previous articles, the link between TCE exposure and fetal heart defects is in doubt, EPA assumes that a single day of exposure to TCE is sufficient to cause harm, so regulatory agencies are prioritizing TCE sites and pushing for rapid vapor-intrusion assessments.

How do we deal with these four compounds in vapor intrusion? Primarily, one establishes whether they’re from vapor intrusion or background. This involves:

  • Determining if indoor constituents are present in soil gas. If not, they’re probably from background.
  • Comparing indoor air to outdoor ambient air. Contaminants in outdoor air represent, by definition, background.
  • Comparing ratios of indoor constituents to soil-gas constituents. Vapor migration from subslab to indoor air involves only dilution, so the ratios of chemical concentrations in indoor air should be pretty much the same as the ratios in soil gas.
  • Conducting a survey of vapor-forming substances inside the building as part of the initial vapor-intrusion assessment. Compounds with anomalously high concentrations in indoor air may be associated with these materials, or with activities and substances used during sampling.
  • Comparing indoor-air concentrations to EPA’s background report, and others. Common background constituents, e.g., BTEX, should generally be regarded as suspect.

More often than not, one or more of the problem compounds represent background, and cumulative risk from the remaining compounds is acceptable. Understanding the sources and significance of these four compounds is critical to eliminating unnecessary costs and efforts.

Author: Mort Schmidt is a Senior Scientist with Cox-Colvin & Associates, Inc. He received his BS and MS degrees in Geology and Mineralogy from The Ohio State University, and has been a Cox Colvin & Associates employee since 1997. His areas of expertise include vapor intrusion and contaminant investigation and analysis, and he currently serves as Cox Colvin’s Practice Leader – Vapor Intrusion Services. Mort is a Certified Professional Geologist with AIPG and is a registered Geologist in Indiana.