Commercial Building & Green Space | SESCO
Compliance and Oversight

Vapor Intrusion: Invisible Liability to Commercial Property Owners

Some building owners or property managers may not be aware that their tenants are breathing potentially harmful chemicals caused by vapor intrusion. Recognition of soil vapor intrusion to buildings and other enclosed spaces occurred in the 1980s with concerns over radon intrusion. The EPA defines vapor intrusion “the migration of vapor-forming chemicals from any subsurface source into an overlying building”. Similar to radon seeping into a home, volatile organic compounds (VOCs) from current or former dry-cleaning operations, auto body shops, print shops, machine shops and retail gasoline stations can diffuse and migrate through the subsurface and permeate indoor air hundreds of feet from the source.

In buildings with lower concentrations of vapor-forming chemicals arising from vapor intrusion, the main concern is whether the chemicals pose an unacceptable risk of health effects due to long-term exposure to these lower levels.  If vapor intrusion results in high concentrations of hazardous chemicals in indoor air, safety hazards such as an explosion or acute health effects are possible. This situation creates a real potential for third party claims involving bodily injury, actual or perceived harm, property damage, remediation/monitoring expense and legal defense expense.

To assist with these challenges, commercial property managers and building owners require an experienced team of professionals including legal counsel and a reputable environmental consultant that understands how to manage this environmental liability.


For purposes of environmental due diligence, the November 2013 ASTM Standard E-1527-13, entitled “Standard Practice for Environmental Site Assessments: Phase I Environmental Site Assessment Process” expressly requires environmental professionals to consider potential impacts to indoor air caused by vapor migration.

For purposes of hazardous waste sites, on June 11, 2015 the EPA, after operating under the draft Vapor Intrusion Guidance for almost 13 years, issued the long awaited “Technical Guidance for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air”, and a companion “Technical Guidance for Addressing Petroleum Vapor Intrusion at Leaking Underground Storage Tank Sites” (“Technical Guidance”) which recommend methods for assessment and mitigation of vapor intrusion and include vapor intrusion screening levels.


To add to the concern, there is debate among State and Federal regulators, pollution liability insurance companies, industrial/manufacturing representatives, and environmental safety professionals, as to what can be considered safe concentrations of volatile chemicals in breathing spaces.

For example, the current Indiana Department of Environmental Management (IDEM) Screening Level for indoor air trichloroethylene (TCE) inhalation is 2.1 ug/m3 (residential) and 8.8 ug/m3 (commercial) while the Occupational Health and Safety Administration (OSHA) permissible exposure for TCE is an 8-hour time-weighted average of 537,000 ug/m3.  The National Institute for Occupational Safety and Health (NIOSH) recommends an exposure limit of 134,000 ug/m3 as a 10-hour time-weighted average. These levels clearly illustrate a significant difference of opinion between regulatory agencies entrusted with protecting the public.

However, the previously mentioned June 2015 EPA Technical Guidance document is significant because it fundamentally changed its approach to vapor intrusion in non-residential buildings by abandoning its deference to OSHA cleanup levels reflected in EPA’s 2002 Vapor Intrusion Draft Guidance.  Therefore, EPA’s guidance-based risk levels and not OSHA’s regulatory indoor air levels determine whether vapor intrusion is a concern in a non-residential building and whether remediation was necessary. Although OSHA has not initiated the necessary rule-making process to change their regulatory indoor air levels, OSHA reportedly is now more or less suggesting that OSHA’s indoor air levels are no longer protective, thereby implicitly supporting EPA’s position. This shift is significant because to date, some responsible parties and insurance carriers with known VOC impacts to non-residential indoor air have elected to apply OSHA’s regulatory levels to justify a “do nothing” approach, effectively exposing their tenants, employees, and customers to contaminated air.

Inconsistent interpretation of the chemical exposures and response actions also creates an uncertainty in a property owner’s risk management strategy.  For example, there are known cases in which more risk-adverse companies ceased business operations and demolished their facility to avoid potential claims by their employees whereas others continue to lease commercial space to tenants with known VOC impacts greater than IDEM Screening Levels and chose not to install a vapor mitigation system or other engineered controls.


The increasing complexity of risk management decisions that Potentially Responsible Parties (PRPs) and property owners must navigate when evaluating potential VOC impacts to on- and off-site structures is becoming more evident.  Vapor intrusion can impact every stakeholder in a property transaction. Particularly, site-owners and investors can find themselves stuck with a problematic property that wasn’t discovered before purchase. This can lead to liability, property value losses and stigma damages, or damages to a property’s value from perceived or real environmental risk. In addition to known sites that are currently monitored by regulators, there are a significant number of these properties that may still have undiscovered vapor intrusion conditions.


To assist with these unique and ever changing challenges, commercial property managers and building owners require an experienced team of professionals including legal counsel and a reputable environmental consultant that understands how to manage this environmental liability.