Navigating Indoor Air & Vapor Intrusion Problems

Navigating Indoor Air & Vapor Intrusion Problems

Awareness of indoor air quality issues is on the rise. Public concern over adhesives, solvents, and other chemicals in the air we breathe is widespread and indoor air contamination is a real public health problem. Government agencies, scientific communities, and the public are increasingly interested in the risks posed by indoor air contaminants and how to mitigate their impact.

Indoor air quality varies widely

In a 2011 study, EPA found that concentrations of indoor air contaminants were lower than previous studies, but the results varied due to recent changes in construction practices, differences in indoor and outdoor emissions from sources such as heating systems, and the prevalence of cleaning and consumer products used in buildings. All of these factors have a significant and evolving impact on indoor air quality.

Don’t forget about vapor intrusion

These so-called “background” sources of volatile organic compounds (VOCs) do not include the now widely recognized risk posed by vapor intrusion from contaminated soil and groundwater beneath buildings. In many buildings, vapors enter through cracks around the foundation or sumps and drains. Now that buildings are more weather-tight, there is less outside air exchange, increasing the risk of exposure to contaminated indoor air.

The challenges of indoor air contamination and vapor intrusion are complex. How do you deal with multiple sources? How significant is the impact? How do we balance future versus present use? Site specific risk assessment can help find creative solutions when used to proactively evaluate risk and response actions.

Options for dealing with vapor intrusion

When a source of contamination is found at a new construction site, a focused evaluation should be conducted right where the building will sit. If this evaluation shows risks, engineered controls should be part of the construction. Fixing problems before the building is completed will be much less expensive than addressing concerns later.

Otherwise, remediation of indoor air contaminants in existing construction can be achieved through soil extraction, a passive sub-slab depressurization system (SSDS), or perhaps a simple fan or air exchange system.

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Senior Technical Manager
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