All building owners and construction managers should be aware of vapor intrusion. Vapor intrusion is when chemicals (including the particularly dangerous benzene) enter the air inside a building, and it can have serious negative effects on health.


What Causes Vapor Intrusion?

Vapor intrusion happens when chemicals contaminate soil or groundwater and then generate vapors that enter buildings through cracks or other weaknesses in the structure, like in a building’s foundation. These potentially harmful chemicals are known as Volatile Organic Compounds (VOCs).

VOCs often come from factories or underground storage tanks and can enter the soil via spills and leaks. Another common culprit is the dry cleaning industry — before regulations around chemical disposal were put into place, chemical waste from the dry cleaning process was often disposed of down drains. Decades later, these chemicals remain a common cause of vapor intrusion in nearby buildings.

What Are the Dangers of Vapor Intrusion?

Among the various problems that VOCs can cause, the health issues are substantial. Potential effects of exposure to VOCs include, but are not limited to:

  • Eye irritation

  • Respiratory irritation

  • Nausea

  • Headaches

  • Cardiac issues

  • Cancers

VOCs such as trichloroethylene (TCE), tetrachloroethylene (PCE), radon and methane have all been shown to be harmful to human health. Organizations and building owners can even be liable for health issues caused by VOCs, and property values can also plummet if vapor intrusion is present.

Some VOCs can even ignite under certain conditions. The presence of methane or petroleum-based products can dramatically increase the chances of fires or explosions in a building!

The Environmental Protection Agency (EPA) has strict requirements for the quality of air in residential and commercial properties. The emergence of COVID-19 also saw the EPA promote the Clean Air Building Challenge, a set of best practices for maintaining indoor air quality. While these practices are highly recommended, they primarily involve the use of HVAC to “dilute” air. Vapor intrusion cannot be dealt with solely through these methods.

How To Mitigate the Risk of Vapor Intrusion

Thankfully, vapor intrusion can be prevented or mitigated by a number of methods.

Passive Vapor Intrusion Mitigation Methods

Passive vapor intrusion mitigation (or VIM) methods include:

  • Vapor Intrusion Barriers: Vapor intrusion barriers are watertight membranes used to seal off potential entry points for vapors. They are typically installed under the foundation of buildings during construction. Vapor intrusion barriers are available in a range of different materials and thicknesses.

  • Concrete: Concrete is typically used for foundations and can be added to seal cracks or other entry points.

  • Venting: Venting layers can be installed beneath buildings (either during or after construction). These direct vapors to disperse around the exterior of buildings rather than entering them.

Active Vapor Intrusion Mitigation Methods

Active VIM methods include:

  • Sub-slab depressurization (SSD) systems: SSD systems involve digging a suction pit into a slab and installing an electric fan to blow vapors outside.

  • Building over-pressurization: Building over-pressurization involves using HVAC systems to increase indoor air pressure so that air flows out of the building rather than into it.

Combinations of multiple methods — passive and active — can be particularly effective at reducing vapor intrusion. However, not all VIM systems are ideal, and choosing the right materials is essential.

What Are the Dangers of Benzene Contamination?

One VOC that is particularly dangerous is benzene. Benzene is a known carcinogen and has been linked to both short-term and long-term health issues.

Short-term effects of benzene inhalation include:

  • Headaches

  • Drowsiness

  • Dizziness

  • Loss of consciousness

  • Eye irritation

  • Respiratory irritation

  • Skin irritation

Long-term effects include:

  • Aplastic anemia

  • Reduced numbers of red blood cells

  • Reproductive effects

  • Increased chance of leukemia

In addition, benzene is a fire risk, similar to methane.

Benzene comes from a wide variety of sources, including gas stations, vehicle exhaust and coal and oil emissions. It is also used in detergents, dyes, paints, pharmaceuticals, plastics, rubber and many more products.

How To Mitigate the Risk of Benzene Contamination

Benzene is a hydrocarbon. Hydrocarbons migrate quickly and can damage certain materials. In order to prevent benzene contamination, the right vapor intrusion barrier is needed — opt for a hydrocarbon resistant membrane.

How EPRO Can Help

If you’re looking for solutions to alleviate the risk of contamination, you’re in luck. Here at EPRO, we put occupant and building safety at the top of our priority list — that’s why we offer a variety of products that can be used in VIM systems.

EPRO Vapor Intrusion Barriers

  • Geo-Seal® 100: Geo-Seal 100 is a patented composite sub-slab barrier with high durability and puncture resistance. With a thickness of 96 mils, it consists of three layers — Geo-Seal BASE, Geo-Seal CORE (60 mil) and Geo-Seal BOND. Geo-Seal 100’s HDPE sheets are resistant to hydrocarbons and other chemicals, and it has been proven to shield against all common VOCs.


  • Geo-Seal 100 is particularly useful for construction projects situated on brownfield land or other sites potentially affected by vapor intrusion. It is approved by multiple regulatory agencies.

  • Geo-Seal® EFC: Geo-Seal EFC is a coating system designed to be applied to concrete floors. It is comprised of 6 mil Geo-Seal EFC PRIMER and 20 mil Geo-Seal EFC coating. It provides more chemical resistance than traditional epoxy resin-based coatings and is specifically formulated to resist petroleum hydrocarbon and chlorinated solvent vapors.


  • Geo-Seal EFC is particularly useful for adding an extra layer to existing VIM systems and can be used to take over the function of an existing sub-slab vapor collection system without the need for expensive removal of the existing slab.

  • Geo-Seal® EV40s: Geo-Seal EV40s is a single-sheet membrane consisting of ethylene-vinyl alcohol (EVOH) membrane with a geotextile layer. This composite membrane is thicker and stronger than similar single-sheet membranes and can be smoke tested to ensure a completely vapor-tight seal.


  • Geo-Seal EV40s is 41 mils thick and meets Class A vapor barrier standards. The spray-applied Geo-Seal CORE layer is more effective at sealing potential entry points than traditional tape sealing methods. It is ideal for quick installations and as an accompaniment to sub-slab ventilation systems.

EPRO Venting Systems

Our Vapor-Vent™ is a composite vapor collection system that reduces the build-up of vapor underneath a structure. Vapor-Vent consists of a three-dimensional polypropylene core that is lightweight and flexible and a geotextile filter fabric that prevents substrates from clogging the pipe.


Vapor-Vent can be used as one component of a VIM system and alongside vapor intrusion barriers. It is intended for use within permeable substrates rather than in contact with groundwater.

EPRO Can Provide the Right VIM System for Any Project

We understand that every project is different. Our team of experts can help you plan vapor intrusion mitigation and benzene contamination mitigation systems that work for your project, whatever its specific circumstances and unique challenges. We also offer extensive warranties to provide our clients with peace of mind.

Plus, we have perfected our process to ensure that your project gets the solution it needs without any hassle. Once you’ve filled out our online form, our professionals will assess the site and goals of your project and present you with product options to fit a range of budgets. We will identify potential problems and challenges of your specific project and offer creative solutions.

After your chosen EPRO system is applied and your project reaches completion, we’re still here to help and advise should issues arise — but we’re confident that your project will run smoothly.

Are you ready to get your project started? Contact our team today!