‘Air’ial Assault: How Contaminated Air From Past or Current Operations Can Impact Your Property & Surrounding Community

EnviroForensics’  Vapor Intrusion and Mitigation lead shares his expertise on how contamination in the air from current and/or past operations may be impacting your property and community health. 


Access to fresh air and water are required to sustain a healthy life and should not be taken for granted. Do you know if current and/or historical operations at your property are adversely impacting the breathing air within your building or nearby structures? If you have read EnviroForensics’ past articles, we have explained the basics of environmental contamination, how it impacts properties, and the process by which an environmental consultant like us can assist with investigating, mitigating, or remediating a contaminated property. In this article, I am focusing on explaining how contamination in the air from current and/or past operations may be impacting your property and nearby properties.


Let’s briefly review how environmental contamination can occur. Environmental contamination begins with a sudden and/or incidental release(s) of hazardous materials into the environment. These are referred to as “spills” and can occur in areas where hazardous materials are used. Perhaps it was a leaky connection to a drycleaning machine that dripped solvent for years, or a sudden accident where a container of solvent (virgin or waste) tipped over and released out the back door soaking into the asphalt parking lot or ground surface. These areas where contaminants are released are termed “source areas”. The contaminants in source areas can migrate downward in the subsurface due to gravity. Because the contaminant molecules from a spill can bind to soil particles, a source area can continue to release contaminants into the subsurface over time. Contaminants that migrate vertically can reach the groundwater and spread as they dissolve into the groundwater and migrate in the direction of groundwater flow. This is a common way for contamination to travel away from a source area and impact adjacent properties. So now that you know how a contaminant can be released and enter the subsurface environment; how exactly can this impact air quality?


Drycleaning solvents like tetrachloroethene (PCE), also known as perchloroethylene or commonly referred to in the industry as PERC, are volatile organic compounds (VOCs). As these chemical compounds are volatile, they readily evaporate from liquid to vapor phase. Let’s take nail polish remover for example: as soon as you open the container you will smell the acetate in the air immediately. This is because acetate is volatile and readily evaporates from its liquid form to its vapor form when exposed to ambient air. The potent odor from the nail polish container, or PERC container within your building, is an indicator of the vapor phase quickly filling a room when a container is opened. Now if we consider a contaminant source area where PCE was spilled into the subsurface, we can understand that the material will readily evaporate, or ‘off-gas’, and the vapor phase will contaminate the surrounding subsurface air residing within spaces between soil particles. Given the characteristics of vapors, the contaminated air will migrate laterally and upward towards the ground surface. Contaminant vapors in the subsurface air will continue to spread outward as contaminants move from areas of high concentration to areas of low concentration.

As contaminants off-gas from impacted soil and groundwater, they can potentially produce a soil gas contaminant plume (or vapor plume) which is basically a subsurface ‘cloud’ of contaminated air. These soil gas plumes can accumulate beneath structures and enter the structure’s breathing air, this is commonly referred to as “vapor intrusion”. This can occur in a variety of structural settings, whether a structure is constructed over a crawlspace with a gap between the soil and floor of the building or if it is a concrete slab placed directly on the soil. Contaminated air from the subsurface can seep into the structure from the exposed soil of a crawl space or through cracks, floor drains, sumps, or other penetrations in a concrete slab. Depending on the contaminant concentrations of the vapor plume, breathing the indoor air impacted with contaminant vapors could adversely affect the health of occupants within the structure. Vapor plumes can exist in the subsurface and impact structures long after the spill and spread of contamination initially occurs. As contamination released to groundwater can allow contaminant to travel away from the source area, vapor intrusion can occur at structures well away from the initial source area of contamination as well. 


These air impacts can go unnoticed as they are not typically concentrated enough to be observed by your sense of smell and require specialized sampling and analytical testing to evaluate the concentrations in indoor air. To ensure that property owners and residents near known source areas and vapor plumes are not being exposed to potential health risks from these vapors, it may be necessary to test the air quality.  Soil gas monitoring wells can be installed nearby known environmental contamination to evaluate the subsurface conditions in the area. If samples collected from soil gas monitoring wells indicate the presence of contamination at certain levels, then nearby structures may be further evaluated. Indoor air samples can be collected from within the occupied living spaces of structures to evaluate indoor air quality while samples can also be collected outdoor to evaluate the air conditions outside for comparison. In addition, small sampling points can be installed through the concrete slab of a structure, known as sub-slab vapor sampling points, and used to collect samples from beneath a structure. Evaluating the air conditions beneath the concrete slab aid in determining what can potentially enter the structure through the concrete slab or other penetrations. 

In addition to environmental contamination in the subsurface leading to vapor intrusion and contaminated breathing air withing structures, business operations can impact indoor air. We occasionally have our clients ask us if subsurface impacts can affect breathing air of structures, how are drycleaners able to use these solvents within their own facilities? And can actively using them present the same health issues to occupants in adjacent or nearby properties? 

Many industrial facilities like drycleaners legally use known hazardous substances to carry-out their manufacturing or other business operations. As hazardous substances can provide risk(s) to workers using certain products, the Occupational Safety and Health Administration (OSHA) requires proper communication of the substances used by the employer. This communication includes acceptable indoor air exposure levels of the chemical used in a business environment. 

Concentrations of the volatilized chemicals produced during business operations can permeate the indoor air and other materials/contents within the structure. The contaminated air within a building (generated from operations or vapor intrusion) will spread outward exhausting to the outdoors through doors, windows, exhaust fans, etc. at which point they migrate along with the general wind direction. Depending on the property layout and surrounding properties, this contaminated air could potentially infiltrate nearby structures’ breathing air, introduced through open doors and/or windows, or can even be entrained into ventilation systems of a nearby structure. In some scenarios where a facility may share a common interior wall with an adjacent business (like in a strip-mall for example), the air concentrations from materials being used in one business can permeate through the walls and/or above the shared ceiling or attic space into the adjacent business. Although adjacent spaces may have their own separate ventilation system and not have direct access to the area where the contaminated air is generated, air mixing can still occur and impact adjacent spaces.

As we previously discussed, OSHA permits a facility using hazardous materials to have certain concentrations of contaminants in the workers breathable air, but what about the breathing air of the adjacent business unit or the potential residential structure across the alley? The permissible levels allowed by OSHA are prescribed for workers, not for the occupants of nearby structures. When environmental investigations are performed, indoor air concentrations are compared to levels prescribed by the local and/or state government, or in some cases the Environmental Protection Agency (EPA). These levels are much lower, or more stringent, than OSHA levels as the occupants of these structures are not electing to work at a business or live in a residence that knowingly stores or uses hazardous chemicals. As one might imagine, this can be problematic for operators of facilities that use hazardous materials. Although they can maintain compliance within the work environment, the same air concentrations may not be in compliance if determined to be present in adjacent or nearby properties.


Now that I’ve explained scenarios by which past and/or current hazardous material storage, use, and releases can impact indoor air, you’ll be relieved to know that appropriate measures can be taken to mitigate the impacted air and ensure a healthy breathing environment. EnviroForensics has installed numerous systems, designed to mitigate the potential for unwanted contaminated air from entering the breathing air of a structure. For vapor intrusion scenarios, where unwanted vapors are entering the structure from the subsurface beneath a structure’s foundation, a vapor mitigation system can be installed. A vapor mitigation system is designed to interrupt the pathway by which vapors enter the breathing air. As structural foundations can vary, vapor mitigation systems can be comprised of multiple components, for example: active venting, passive venting, sub-slab depressurization extraction points, vapor barrier in crawlspaces, pre- and post-construction installations, vapor matting, etc. For scenarios where unwanted air generated from active operations is the issue, ventilation systems can be rerouted and/or modified to mitigate the issue. Once a system is in place, long-term operations, maintenance, and monitoring is often completed to continue to confirm the system(s) are operating as designed.  

Rest assured, EnviroForensics is here to assist you for if you have concerns that one of these scenarios may exist at your property. Our team of scientists have a wealth of experience at tackling complex environmental issues to aid in managing liability for clients and minimizing any potential threat or undue harm from air contamination in their communities. Contact us to learn more on how we can help you address your environmental risks in a business-friendly approach 

As seen in Cleaner & Launderer

5 Things to Know about Vapor Intrusion, Your Home, and Your Health


Vapor Intrusion, or VI, occurs when contamination beneath the ground emits toxic vapors that can travel through the soil and enter the interior spaces of houses and buildings. The types of contamination most commonly associated with VI concerns are industrial solvents like chlorinated volatile organic compounds (CVOCs), and petroleum products like gasoline.  The Environmental Protection Agency just released final guidance on vapor intrusion issues, which regulates how inhalation exposures from VI are assessed and controlled.

There has been a great deal of concern in recent years about the potential for harmful health effects related to VI exposure, and many people are unintentionally involved.  In turn, there has been a lot of concern from those who hold legal liability for the contamination, even if they didn’t cause it.  Every day, it seems, a new VI case emerges where one or more homeowner learns that they and their family may have been exposed in the past, or are now being exposed, to harmful vapors from contamination.  Even commercial buildings and strip malls can be subject to VI.  The affected buildings are typically located near, but not necessarily adjacent, to current or historical drycleaning facilities, factories, or gas stations.  If you own a home or building located near a commercial corridor or close to a manufacturing area, you may wonder if VI is a problem at your home.  Here are 5 things to consider when you ask that question and contemplate the potential answer.

When looking around your home or building to determine if it’s located near a potential source of harmful vapors, keep in mind that vapors travel in the subsurface.  They move within the open, air-filled spaces in the soils above the water table.  There are many scientific factors and variables that affect the direction and extent to which vapors move.  As such, it’s problematic to predict.  Generally, many regulatory agencies use a rule of thumb whereby if a structure is within a 100-foot radius of a release of volatile contaminants, it should be further assessed for potential VI issues.

Just because there isn’t a gas station or dry cleaner near you now, it doesn’t mean that one didn’t used to be there. Commercial and industrial properties are being bought and sold on a daily basis, and individual commercial tenants come and go. Especially in busy traffic corridors that pass through residential parts of town. As a result, there may be no indication that a dry cleaner operated in your corner strip mall for 20 years, and then moved out 10 years ago. Also, you can probably expect that in older parts of town, just about every corner of a busy traffic intersection accommodated a petroleum gas station at some point in history. There are ways of learning about the commercial history and land transfer records at local libraries. An individual can go find the City Directories and look it up.  There are also commercially available sources of this data for wider real estate uses.

Although the scientific study of how vapors of different industrial origins move within the subsurface is still developing, and the health effects related to breathing them are still under evaluation, the federal, state and local environmental regulatory agencies are very keyed-in to identifying sites with potential VI issues. If a commercial property transaction results in the knowledge that past use included an activity that may have potentially resulted in contamination, it is most often confirmed or denied through the collection and analysis of soil and groundwater samples. If contamination is identified, the state environmental regulatory agency is notified.  The responsible party for the contamination then is required to begin the process of investigating the extent of the impacts and finding who may be exposed to the contamination. The potential for VI is being watched very closely by the agencies. So it is possible, and probably a good idea, to contact your state environmental regulatory agency to inquire if there are any active contamination investigations or cleanups occurring in your vicinity. Their websites may actually have interactive maps or searchable databases where you can find this information on your own. If there is a site in your neighborhood and your structure is within 100 feet of it, you can likely expect a request to for sampling. The best way to know if there is a concern is to let the environmental professionals do their job.  Be sure to put in your access agreement that they’ll let you have the results.

The health effects related to the inhalation of vapors from industrial contamination are still being evaluated.  The exact amount of individual chemicals that are “safe” to breathe is not yet known.  By using overly conservative toxicological factors, and by overestimating the amount of chemicals that individuals may be exposed to, the agencies have developed a set of “screening criteria” to frame exposure.  The goal is to overestimate the potential for harmful effects of VI exposure, and therein addressed and eliminated every actual exposure scenario. The reality for occupants of commercial or residential buildings who are breathing contaminated air, is that the health-based screening level communicated to you is not actually the level at which your health will be immediately harmed. That doesn’t mean that you have to continue breathing it, but there is no need to panic.

In many parts of the country, radioactive radon gas is constantly emanating from decaying rocks and soils. Radon comes into contact with occupied structures and is subsequently breathed by people. This is exactly the same process as VI from contaminant sources. The process of determining if radon is present in private homes has been part of the residential real estate process for many years.  As such, many more people are familiar with radon than VI. The good news is that if your home or commercial building has a radon mitigation system already installed and in operation, you may be protected from subsurface VI concerns. Typically, however, mitigation systems designed for VI from industrial chemicals are more robust.

For more information on Vapor Intrusion and Mitigation, contact us for a confidential consultation. 


U.S. EPA Finalizes Vapor Intrusion Rule for Superfund Sites

A major development in the Environmental Consulting industry. The United State Environmental Protection Agency has published a final rule which effectively adds a vapor intrusion component to CERCLA’sHazard Ranking System (HRS) for Superfund sites. This move finalizes the draft rule from earlier this year, after the incorporation of some public comments. This final rule paves that way for EPA involvement at sites with no known responsible party to address immediate vapor intrusion exposure concerns. Given the fact that vapor intrusion has not previously been considered during the Superfund ranking system, it is likely that a higher percentage of new sites being added to the program will have a vapor intrusion component.

Our Executive Vice President, Jeff Carnahan, LPG spoke with Bloomberg BNA earlier this year, and thinks this will create a need for new advancements in vapor intrusion research and remediation.

“This [regulatory development] is not likely to be the last one. With each additional incremental step in the regulation and highlighting of the exposure pathway, you’re going to see more and more developments in the science and technology,VIStamp

EnviroForensics Vapor Intrusion experts will continue to monitor this development as the new presidential administration and EPA commissioner take office early next year.

EPA Adds West Vermont Street Site to Superfund List

Following nearly a year of speculation, an 18-acre groundwater contaminant plume on Indianapolis’ West Side, has landed the area on the U.S. Environmental Protection Agency’s new Superfund list.  Superfund is a federal program that aims to address some of the most contaminated land and waterways in the country.

In September 2015, the EPA made the proposal to put the West Vermont Street groundwater site on the National Priority List. In 2009, Marion County Health Officials had discovered high concentrations of vinyl chloride (a breakdown product of drycleaning solvents) in the drinking water of three homes near the Allison Transmissions plant, just south of the Indianapolis Motor Speedway.

Proposal Map for West Vermont Street Superfund Site. Courtesy: United States Environmental Protection Agency
Proposal Map for West Vermont Street Superfund Site. Courtesy: United States Environmental Protection Agency


According to EPA officials, there were at least 20 other potentially affected homes in the area, and immediate action was taken to ensure the health and safety of these homeowners. Utility workers diverted the water service from the underground water wells in the area to municipal water.

Even with this measure in place, EPA officials determined the potential danger of the groundwater plume was too much to ignore. Investigations confirmed the migration of the plume could put as many as 18 thousand people at risk of becoming exposed to the contaminant.

EPA officials are now conducting further investigations to delineate the horizontal and vertical nature of the plume, filling in data gaps, and identifying all potential exposure pathways including vapor intrusions. A few potential responsible parties have been identified as a result of their historic operation and known individual contaminant releases on their properties.

EnviroForensics has been involved in SuperFund sites like this one around the Indianapolis area, including the Keystone Corridor Project, and we know how important this work is. We look forward to providing additional information as new developments arise regarding this project.

A Vapor Intrusion Success Story

Sometimes detecting and addressing a vapor intrusion pathway is like a giant game of whack-a-mole. As soon you knock one down, another one pops up, and so on and so forth. One of our teams recently encountered this issue, having discovered that their initial mitigation efforts had not decreased the concentration of tetrachlorethene (PCE) inside an apartment located above a dry cleaner.  Despite this setback, our team dusted themselves off, and went back to work, going by the old addage; if at first you don’t succeed, you try again.

To give you an idea of what we were working with, our site building is a 2-story structure with a dry cleaner on the first floor, and an apartment on the second. The dry cleaner is now a drop-off only location, but had conducted on-site cleaning in the past. We discovered PCE in the sub-slab vapor underneath the structure, which helped us determine there were vapor intrusion risks to both the dry cleaner building and, perhaps more importantly, the apartment above it. We installed a sub-slab depressurization system (SSDS) to address this issue.

Unfortunately, that did not solve the problem. Indoor air PCE concentrations in both the first floor dry cleaner and second floor apartment remained above the residential vapor action level despite the operation of the SSDS. The concentrations were similar on both floors, which suggested direct physical pathways for indoor air movement. The HVAC systems that services these spaces were the most likely culprit.

Armed with this new knowledge, we focused our efforts on the first floor room that houses both of the HVAC systems. We first sealed up the mechanical room, using an air-tight door gasket and sweep. Duct work and piping penetrations in and out of the mechanical room were also sealed and a furnace filter cover was added to prevent the apartment furnace system from potentially capturing vapors from the first floor. We then installed door gaskets between the first floor store and the second floor apartment stairway. The final touch was an energy recovery ventilator (ERV) installed on the apartment’s furnace to increase fresh air exchange.

Early returns suggest this latest attempt to address the problem was successful. The first post-mitigation indoor air sample collected from the apartment did not contain PCE above laboratory detection limits. Our team will conduct a confirmation air sampling event during the upcoming winter months, when conditions will be ideal for a “worst case” air assessment.

In the Environmental Cleanup business, there really isn’t any room for failure. The preceding is a good example of the trial and error we go through when looking for all potential vapor intrusion pathways. Using the experience and ingenuity we have managing contaminations like this, we were able to come up with another solution. And, at least in the short run, it appears the residents of that 2nd floor apartment can breathe easy without having to worry about the potential health risks of exposure to PCE.

image was a courtesy of Washington State, Department of Ecology
image was a courtesy of Washington State, Department of Ecology

Where There is Exposure, There is a Problem: Identifying Exposure Pathways

It may seem like the objective of every project is to completely wipe out contamination, but it’s a little more nuanced than that. Sure, we want to make certain that a client’s property is as clean as it can be for future use, but it’s also important to consider where actual risks to human health occur in situations where a thorough site cleanup isn’t possible. That’s why, when we develop a Conceptual Site Model (CSM) a key component is the identification of potential exposure pathways and receptors. Once we can prove there’s no possible way a human can come in contact with the contaminant, we’re one step closer to obtaining the coveted “No Further Action” letter from the regulatory body with which we’re working.

It all starts with the investigation. In short, we use the data collected from soil and groundwater tests to delineate and characterize the horizontal and vertical nature of the contamination plume. The size, shape, and location gives us a general idea of which structures and buildings may be impacted, and, using this information, we can draw up our CSM.

In the Conceptual Site Model (seen in the simplified figure below) you can see we’ve labeled the actual dry cleaner machine (the established source of contamination) the buildings resting above the contaminated soil and groundwater, the different types of impacted soils,  groundwater and all identified migration pathways.  The contaminant migration pathways are indicated by the arrows in our figure.

Conceptual Site Model Example

The next step is to test those pathways to determine if there’s a potential for exposure, because where there’s exposure, there’s a problem.  We start at the established source, and work our way down and up from there, checking surrounding structures for possible vapor intrusions, and testing soil and groundwater impacts and the possible receptors they could come in contact with (sewer laterals, sewer mains, groundwater wells, and the like.)

Once we’ve determined the existing pathways, it’s time to figure out what (if anything) needs to be done. We conduct an exposure assessment based on the type of receptors being impacted. Those receptors can be humans, utility corridors, drinking water wells, and the like. As an environmental consultant, we want to wipe out any contamination, but we are also beholden to both the institutional constraints and the client’s legal obligations. Identifying the potential exposure pathways at a Site can help us pin-point our focus as we draw up our site closure strategy.



Bloomberg: Struggles Persist to Enhance Vapor Data Innovations

Reproduced with permission from Daily Report for Executives, 153 DER (Aug. 9, 2016). Copyright 2016 by The Bureau of National Affairs, Inc. (800-372-1033) <http://www.bna.com>

Public and regulatory concerns are steadily rising over the risk of health detriments linked to vapor intrusion that seeps into the floors of buildings.

The Environmental Protection Agency continues to warn short-term exposure to trichloroethylene (TCE), a degreaser and primary contaminant spread through vapor intrusion, among pregnant mothers may cause fetal cardiac defects.

And the agency is moving forward with nearly surefire finalization of a rule to add vapor intrusion, the process of volatile compounds migrating through sub-surface groundwater or soil to air in above-ground structures, to the Superfund Hazard Ranking System.

But high-tech developers and vendors are struggling to overcome hurdles in vapor intrusion sensor development, leaving potentially affected communities in the lurch with unreliable or inaccessible data.

Mobile technology isn’t yet sophisticated enough to detect contaminants at necessary precision, even with the historical help of some government agencies, according to recent Bloomberg BNA interviews with consultants and advocates.

That’s leaving vapor intrusion assessment at a deficit. Sensor technology is advancing at breakneck speed in other regulatory areas prone to hazard, such as occupational safety and health and climate change.


Need for Improvement

The EPA nationwide and private industry rely on largely passive sampling of air, groundwater, soil and sub-slabs to model the likely threat posed by a vapor intrusion pathway, the agency says.

That approach traditionally involves canister sampling with gas chromatography/mass spectrometry analysis and other methods to assess indoor air concentrations of common vapor intrusion contaminants, such as TCE and tetrachloroethene (PCE), as well as benzene, toluene, ethylbenzene and xylenes, a chemical group known as BTEX.

Those technologies and tactics, however, fail to effectively diagnose short-term risks, contamination spikes and variability, because they target time-weighted averages, rather than continuous monitoring, experts told Bloomberg BNA.

“There’s a lot of evidence that indoor air concentrations vary enormously, daily, seasonally and by weather. Soil/gas concentrations may also vary seasonally,” Lenny Siegel, executive director of the Center for Public Environmental Oversight, told Bloomberg BNA.

Traditional devices passively sample over the course of 24 hours to several weeks.


Health Concerns

Concerns over contaminants, coupled with a lack of trusted analysis, has even led to the closure of schools nationwide after EPA Region 9 released Superfund guidance in 2014 to highlight the need to safeguard pregnant mothers from TCE exposure.

The guidance points to conclusions outlined in a 2011 EPA toxicity assessment held in a compendium called the Integrated Risk Information System.

“This and other findings in the IRIS assessment of TCE indicates that women in the first trimester of pregnancy are one of the most sensitive populations to TCE inhalation exposure,” the guidance said. “For fetal cardiac malformations, a specific developmental effect, the critical period for exposure is considered to be the approximate 3-week period in the first trimester of pregnancy during which the heart develops.”


Public Disruptions

The Magnolia Elementary School in El Cajon, Calif., which is part of EPA Region 9, shut down for the 2015-2016 school year due to perceived vapor intrusion risks.

A class action lawsuit pointed to a TCE plume in the vicinity brought on by a former aerospace manufacturing plant.

Local school officials took similar action in recent months in Winston Salem, N.C. and Millis, Mass.

States such as New York, Connecticut and Massachusetts also have moved forward with their own revisions to TCE and other contaminant concentration standards, and state agencies have shut down sites due to excessive contamination.

Moreover, the Massachusetts Department of Environmental Protection is likely to dive into revisitation needs for roughly 200 sites already closed after remediation of TCE contamination, agency officials announced in April.

The state’s 2011 revised standards slashed appropriate toxicity levels for residential indoor air TCE exposure more than 14 times, from 85 micrograms per cubic meter (µg/m3) to 6 µg/m3.


‘No Consensus’ Exists


Interested parties continue to debate, however, the TCE exposure linkage with cardiac birth defects.

“There’s no consensus on this [TCE] issue. You put 10 scientists in a room, it’s five and five. It’s like Republicans and Democrats; its split down the middle,” Blayne Hartman, vapor intrusion expert with Hartman Environmental Geoscience, told Bloomberg BNA.

The Silicon Valley Leadership Group contested the guidance in 2015, arguing industry is shouldering drastically increased compliance costs despite the region’s failure to properly roll out the policy change.

The EPA, however, rejected that complaint.

“There are no significant uncertainties that have arisen since 2011 that were not considered prior to the release of EPA’s final toxicity assessment as to whether TCE causes fetal heart defects,” Region 9 Superfund Director Enrique Manzanilla told the group in November 2015.

Meanwhile, the EPA’s 2015 release of national vapor intrusion guidance already pushes site managers and risk assessors to consider sub-surface hazards.



Emerging Technology

A handful of developers are spearheading sensor innovation and other technology tied to vapor intrusion assessment.

The challenge is to deploy user-friendly, continuous monitoring, mobile devices with parts per billion precision at prices around $1,000 each.

A Palo Alto, Calif., startup named Entanglement Technologies is one potential vendor pushing the envelope.

The company’s lead product, dubbed the Autonomous Rugged Optical Multigas Analyzer, is a mobile, rapid response device.

“It can be costly to screen large areas to determine when that [vapor intrusion] pathway is important, to what degree it’s a concern to health and to be able to cheaply and efficiently either determine that mitigation is required or to determine that mitigation is not required,” Tony Miller, Entanglement chief executive officer, told Bloomberg BNA. “Our instrument allows you to quickly determine where it is important to measure so you can get that study done more quickly, and when it’s done more quickly, it’s done more cheaply because a significant fraction of costs is associated with labor.”

The product, however, isn’t yet on the market. Miller predicted he’d start selling the device in 2017.



Fusion Technology Being Deployed

Another trailblazer already deployed nationwide is a fusion of a traditional gas chromatography instrument with more precise, customized data intake capacity and analysis, created by Hartman and Mark Kram, founder and chief technology officer at Groundswell Technologies.

“I firmly believe that continuous monitoring, regardless of whether it’s with a sensor or an analytical system, is the only way to be able to understand appropriate dynamics and risks and then respond in a timely fashion,” Kram told Bloomberg BNA. “That in and of itself would allow me to confidently classify this as the most innovative option out there.”

The Hartman-Kram device, which costs roughly $35,000-$60,000 each, is similar in size to a small suitcase.

Other groups like the North Carolina-based RTI International are moving forward with their own products.



Agency Assistance/Marketability

The Entanglement product received development funding from the National Science Foundation and the National Institutes of Health.

Entanglement’s Miller said enhancement is the only thing keeping his product off the market.

“We have a set of technologies which are fundamentally new, and there has been time required to develop the technology. It hasn’t been a market force issue,” he told Bloomberg BNA. “We’re now at the point where we have successfully demonstrated these technologies, so now it’s just making the transition to commercialization.”

Despite Miller’s 2017 pledge, some experts say developers as a whole are at least a half dozen years away from marketing a product en masse.

But other agencies don’t seem to be weighing in with real resources despite the apparent risks at play.



EPA Unaware of Assistance

The EPA’s Office of Research and Development said it is unaware of any ongoing research development or private sector assistance for vapor intrusion.

The National Aeronautics and Space Administration (NASA), an agency involved heavily in sensor innovation, also isn’t sponsoring or developing environmental contamination innovation, a spokesman said.

The National Institute of Standards and Technology and the Environmental Security Technology Certification Program, an agency that has traditionally funded vapor intrusion assessment research, didn’t respond to Bloomberg BNA requests for comment.

But other experts questioned whether a lack of demand is restraining innovation.

“What we have is a chicken and egg problem,” the Center for Public Environmental Oversight’s Siegel said. “The regulators don’t require these technologies because they aren’t quite on the market yet, and the companies aren’t pushing, at least, the portable ones; they’re reluctant to develop them because there’s no requirement for them.”

On top of that, the possibility remains that the EPA may reverse its cardiac defect guidance, Hartman said.

“That may take away the demand, or [threshold standards] might go up enough that maybe some of these sensors can get low enough.

That’s all speculation,” he said.



Superfund Connection?



The EPA’s looming finalization of the rule (RIN:2050-AG67) to add vapor intrusion to the Hazard Ranking System under Comprehensive Environmental Response, Compensation and Liability Act, better known as Superfund, is generating more interest in and concern for sub-surface hazards.

And while the EPA Region 9 TCE guidance is the most potent precipitator, the Superfund listing may in part drive the push for technological innovation, the experts said.

“This [regulatory development] is not likely to be the last one. With each additional incremental step in the regulation and highlighting of the exposure pathway, you’re going to see more and more developments in the science and technology,” Jeff Carnahan, a vapor intrusion expert with EnviroForensics, an environmental engineering company that represents dry cleaners, told Bloomberg BNA.

Technological improvements may actually, however, unveil a smaller risk posed by sub-surface contaminants, Siegel said.



Source of Contamination

“If [the source of contamination] turns out to be a can of gun cleaner, than you know where it’s coming from. If it’s a crack in the floor, you know where it’s coming from,” he said, referring to household items that may emit contamination. “This is actually a major issue at a lot of sites where they find something but they don’t know whether it’s really vapor intrusion.”

The rulemaking doesn’t call for revisitation of current Superfund sites or those proposed and deleted.

A decision to include revisitation mandates would have been a game-changer for innovation demand though, Kram said.

“The regulators have to adopt a balanced position, as they do not want to unnecessarily burden the regulated community with high compliance costs,” he said. “Their current policies indicate that they are convinced that acute TCE exposures of low concentrations can be harmful. In addition, they acknowledge that conditions are dynamic. This creates a significant challenge regarding the methods they are currently accepting for acute TCE related risk characterization.”

Eliminating Background Sources of Vapor Contamination at Active Dry Cleaners

Vapor intrusion continues to be one of the most common exposure pathways that we investigate in our work at EnviroForensics.  We’ve mentioned in past blogs that many household and commercial products can serve as background sources of contamination in indoor air, making it difficult to determine how much contamination is truly due to vapor intrusion from the subsurface.  The presence of background sources is likely to increase concentrations of contaminants in indoor air samples if they are not eliminated prior to sampling and this bias may misrepresent indoor air as it relates to vapor intrusion.  Therefore, elimination of background sources is necessary to obtain a true measurement of indoor air quality related to vapor intrusion.

But what about cleaning products and emissions at an active dry cleaning businesses?  Dry cleaning emissions are also considered a background source that can contribute to indoor air conditions, but removing them is not as easy as simply moving a bottle of cleaning supplies out of the building before samples are collected.  IDEM recently required indoor air sampling in each tenant space at a strip mall where one of our clients owns a coin operated laundromat and actively performs dry cleaning with PCE and TCE. The EnviroForensics team had to go the extra mile to make sure background sources were eliminated as best as possible before collecting the air samples.

After assessing the strip mall’s basic construction and configuration to gather information pertaining to air circulation, we determined that the best approach was to physically remove as many cleaning materials containing PCE or TCE as possible and then complete a fresh air exchange in each tenant space at least 48 hours before sampling.  We worked with our client to determine a period of time when his business could continue to operate but cease dry cleaning for approximately three (3) days.  Cleaning products that could easily be removed were taken out of the building, but materials were not drained from the dry cleaning machine and dry cleaned clothes were wrapped in plastic and left in place.

After coordinating with the other businesses in the strip mall, a fresh air exchange was conducted in each tenant space using a ventilation fan to draw air from inside the building to the outside, allowing fresh air to flow in.  When the air exchange was complete, the EnviroForensics team waited 48 hours before collecting indoor air samples inside each tenant space.  In doing so, the project team able to satisfy the IDEM requirement for vapor intrusion assessments, making sure that the samples collected were truly representative of vapor intrusion from subsurface conditions.

EnviroForensics continues to think outside the box to identify viable solutions that will minimize the burden on our client’s ability to run their business while addressing their environmental liabilities.

‘Tis the season for Vapor Intrusion Testing!!


Indoor air sampling canister used to measure subsurface soil gas during a vapor intrusion assessment

The schedule at EnviroForensics during the summer and winter months are jam-packed with indoor air and soil gas assessments. During these time frames every year, field staff head out with sampling canisters and equipment in tow, checking businesses and homes for Vapor Intrusion impacts. This includes looking for cracks and other structural fallacies where volatilized chemicals present in the subsurface can sneak into the indoor air of buildings and homes. This is no mere coincidence. The winter and summer months are optimal times to test for Vapor Intrusion due to both indoor and subsurface conditions, as well as state-mandated testing parameters.

Indoor air concentrations can be difficult to measure given the many variables that need to be considered. Outside barometric pressure and temperatures, soil temperature and moisture content, ground water levels, building construction, the integrity of the foundation, potential preferential pathways, and indoor-outdoor air exchange rates can all affect vapor migration through the ground and into a building. Due to the high variability in indoor air and soil gas sampling results, and the limited amount of data collected for analysis, industry experts consider it to be more efficient and health protective to collect vapor samples under what are considered “worst-case conditions” in order to determine if vapor intrusion is indeed occurring. Collecting samples during “worst-case conditions” provide a better understanding as to just how high the chemical concentrations can get in the indoor air.


  1. Windows and Doors are Closed
    Vapor Intrusion is more likely to occur during the Summer and Winter months because doors and windows tend to remain shut, and tenants are using their heating, ventilating, and air conditioning (HVAC) systems during these time periods exclusively for the circulation inside the building. These factors alone promote a higher risk of vapor intrusion. Keeping the windows and doors shut allow any chemicals entering the building or house to accumulate due to the decreased air circulation and decreased air dilution from fresh outside air. Additionally, the HVAC system can create a pressure differential that actually pulls vapors up from the subsurface.
  2. The Water Table Declines
    Below the subsurface, where the chemical contamination is located, conditions are ripe for “worst case conditions.” Since the water table tends to drop during the Summer and Winter months in Indiana and the soil moisture content decreases, more pore space is created in the vadose zone, allowing more vapors to collect below the foundation. With a higher probability of vapors sneaking into a building, the summer and winter conditions tend to provide us with the most accurate measuring stick for the worst case scenario than the rest of the year.

Most state regulators make collecting samples during “worst-case conditions” a requirement in Vapor Intrusion investigations. For example, The Indiana Department of Environmental Management (IDEM) will not give a “no further action” on a site unless sampling data has been collected during the window of time when conditions are ideal for Vapor Intrusion to occur and the concentration of the volatile organic compound (VOC) is below levels that could prove dangerous to human health.

The concept of Vapor Intrusion and the study of its environmental impacts is still in its relative infancy. With each passing year we’re learning more about this type of exposure pathway and what we can do to better detect it. Science has taught us that the summer season isn’t just for baseball, barbecues, and beaches, and the winter time isn’t just for scarves, snowmen, and skating. The two seasons are also the optimal times to get the best possible understanding of the air quality inside your home or business.  The better we understand the air we breathe, the more likely we can protect it from chemicals that pose a potential risk to our health.

Learn more about our Vapor Intrusion Assessment and Mitigation Services.

Background Sources in Disguise

As we’ve mentioned in past blogs, one of the scariest ways for a contaminant to get into your home or business, is in the form of vapor, through the cracks in your foundation and floors (Vapor Intrusion). EnviroForensics conducts a multitude of indoor air vapor intrusion assessments each year at structures located near or over a source of subsurface contamination. These assessments help us figure out if the volatile chemical is finding its way into the structure. But they can tricky, since the same chemicals which potentially reside beneath the surface are also commonly found in household products like hobby glues, degreasers, automotive products, etc. (examples pictured below) These materials are called “background sources” and their presence can be problematic in assessing which indoor air impacts are truly coming from the subsurface rather than products already present within the building.  EnviroForensics conducts extensive background assessments and documents the materials present prior to completing indoor air testing in order to account for any materials which may contain the chemicals being investigated. These materials aren’t always present, but when they are, it is important to remove them prior to sampling in order to avoid an inconclusive data set which is not truly a representation of conditions caused by contaminant vapors entering the breathing air from the subsurface.  A traditional background assessment consists of combing through common household materials, and reading through the lists of active ingredients to confirm the lack or presence of suspect chemical compounds. But can we always trust the fine print of these products? Recently, EnviroForensics discovered that this is not the case.

During recent vapor intrusion testing activities, EnviroForensics identified a background source of tetrachloroethene (PCE) within a glue product which did not list PCE as an ingredient (I know, very tricky). This was made possible due to the fact that EnviroForensics has some of the finest professionals and modern testing equipment to identify and unmask these background sources in disguise. EnviroForensics has an in-house certified analyst trained to operate the Hazardous Air Pollutants on Site (HAPSITE) gas chromatograph/ mass spectrometer (GC/MS) instrument which analyzes air in real-time and provides laboratory-quality analytical results. Utilizing the HAPSITE instrument in the field facilitated the identification of a material containing PCE which did not have the compound listed on its label. With EnviroForensics’ efforts and the use of sophisticated testing instruments, the material was removed from the property prior to completing an indoor air assessment, therefore avoiding the collection of an inconclusive data set which would have hindered progress and over-estimated the health risk to occupants from vapor intrusion.


Common Background Sources That May be in Your Home