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. 

BY: JORDAN GOFF, LPG

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.

HOW ENVIRONMENTAL CONTAMINATION OCCURS

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?

HOW VAPOR INTRUSION OCCURS  

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. 

TESTING AIR QUALITY FOR VAPOR INTRUSION

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.

MITIGATING VAPOR INTRUSION

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

LEARN HOW VAPOR INTRUSION CAN IMPACT INDOOR AIR QUALITY IN BUILDINGS AND THREATEN HUMAN HEALTH, AND FIND OUT WHAT CAN BE DONE TO MITIGATE THIS RISK. 

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.

1. SUBSURFACE VAPORS CAN TRAVEL A SIGNIFICANT DISTANCE FROM ITS SOURCE
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.

2. PAST SOURCES OF VI MAY BE HIDDEN FROM VIEW BY PROPERTY REDEVELOPMENT.
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.

3. WHEN A SOURCE OF VI IS FOUND BY ITS RESPONSIBLE PARTY, THEY ARE REQUIRED TO FULLY INVESTIGATE AND ADDRESS ANY POTENTIAL EXPOSURE. 
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.

4. THE NEED TO INTERVENE IF VI IS OCCURRING AT YOUR HOME OR BUILDING IS ASSESSED BY THE REGULATORY AGENCIES USING CONSERVATIVE SCREENING LEVELS.
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.

5. EXPOSURES IN THE HOME FROM NATURALLY OCCURRING RADON GAS AND VI FROM CONTAMINATION ARE ELIMINATED IN ESSENTIALLY THE SAME FASHION.
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. 

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,

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

LEARN WHY THE WINTER AND SUMMER MONTHS ARE THE BEST TIMES OF YEAR TO TEST FOR VAPOR INTRUSION

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.

SAMPLING AND MEASURING INDOOR AIR IS COMPLICATED
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.

TWO MAIN REASONS WHY TESTING FOR VAPOR INTRUSION HAPPENS IN THE SUMMER AND WINTER 

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.

WORST CASE CONDITIONS REQUIRED BY REGULATORY COMMUNITY
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.

UNDERSTANDING YOUR VAPOR INTRUSION RISK GIVES YOU A BETTER UNDERSTANDING OF THE AIR YOU BREATHE
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.

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