Jump to main content or area navigation.

Contact Us

2012 EPA Research Progress Report

EPA Science Supports Vapor Intrusion Guidance

Most threats to people in buildings, such as fire, flood, hazardous spills, or structural damage, are dramatic and easy to identify. But while it may not be something worthy of coverage on the evening news, vapor intrusion—the contamination of indoor air by harmful gases, both naturally occurring (such as radon) or resulting from chemical spills, that migrate upward from the ground or ground water—also poses serious health risks.

EPA scientists have provided measurements and analysis methods for a new guidance document to better evaluate the problems associated with toxic chemicals that seep into people’s homes through vapor intrusion.

During a two-year study, EPA scientists investigated spatial and seasonal changes in the concentrations of vapors, including volatile organic compounds (VOC) and radon, in indoor air in a test residence. They also looked at soils and ground water near the residence.

The outcomes of the study were published in October 2012 in a report titled, Fluctuation of Indoor Radon and VOC Concentrations Due to Seasonal Variations. Results from the study, along with several other documents and tools were compiled as part of the Agency’s Final Subsurface Vapor Intrusion Guidance, made available on November 30, 2012.

This guidance document provides reliable ways to measure vapor intrusion and answers questions first posed in the 2002 EPA document on the same topic. The results of the research and guidance provide environmental managers and others from EPA Regional Offices and states with easy-to-understand ways to evaluate sites for VOC vapor intrusion.

Additional ongoing EPA research on vapor intrusion includes developing approaches for measuring vapor impacts, evaluating sampling tools to assess impacts at petroleum spill sites, and modeling studies to better understand the screening of certain vapor intrusion chemicals. The suite of research supports efforts to develop assessment approaches for contaminated sites and buildings, and to inform multiple regulatory efforts related to vapor intrusion issues.

Jump to main content.