VOCs that evaporate from polluted soil and groundwater can create chemical vapors underground. If these vapors move and come in contact with a building, they may enter through cracks in the foundation, around pipes, or through a drain system. The VOCs can then contaminate indoor air. This process - when pollution moves from air spaces in soil to indoor air - is called vapor intrusion.
For more information about the steps in a vapor intrusion investigation, see the Minnesota Pollution Control Agency Vapor Intrusion webpage.
Vapor Intrusion in Residential Buildings
Information sheet with general information about vapor intrusion in residential buildings
- English: What is Vapor Intrusion? (PDF)
- Spanish: ¿Qué es la intrusión de vapor? (PDF)
- Somali: Waa Maxay Uumiga Aan la Rabin? (PDF)
Information sheet with general information about vapor intrusion in commercial buildings
Vapor Intrusion and Health
The purpose of a vapor intrusion investigation is to determine if there is a possible risk to the health of people that can be stopped. For there to be a health concern, contaminated vapor has to get into the indoor air at relatively high levels AND people need to breathe the contaminated indoor air vapor over time.
Buildings included in a vapor intrusion investigation are chosen with the aim of finding out whether there is any risk for vapor intrusion or a potential health concern. Health risks from vapor intrusion are usually low. However, the risks may be greater when people are exposed to high amounts of some chemicals for a long time, or if exposed people are sensitive or their health is compromised.
Examples of people who may be sensitive include:
- women who are pregnant or may become pregnant
- infants and young children
- elderly persons
- people who are living with chronic disease or a compromised immune system
Because the risks are avoidable, we want to take steps to reduce or eliminate vapor intrusion where possible. If you have concerns about anyone living in your home or building who may be a sensitive individual, please contact MDH.
Information sheet about who MDH considers more sensitive to vapor intrusion health risks (in homes)
- English: Your Health and Vapor Intrusion (PDF)
- Spanish: La salud y la intrusión de vapor (PDF)
- Somali: Caafimaadkaaga iyo Uumiga Aan la Rabin (Vapor Intrusion) (PDF)
Information sheet about who MDH considers more sensitive to vapor intrusion health risks (in the workplace)
Trichloroethylene (TCE) and Tetrachloroethylene (PCE)
The VOCs found most often during vapor intrusion investigations in Minnesota are the industrial degreaser trichloroethylene (TCE), the dry cleaning solvent tetrachloroethylene (perchloroethylene, PCE), and components of petroleum. Examples of properties that can be sources of these VOCs are industrial manufacturers, dry cleaners, and metal plating shops.
When chemical vapors enter buildings from vapor intrusion, the amount in indoor air is typically not high enough to affect most people's health. The possible health effects from breathing TCE depends on the levels in indoor air, how long people breathe it, and whether and when a pregnant woman is exposed.
- Women who are in the first 8 weeks of pregnancy are the most sensitive to TCE exposures because it may increase the risk of heart defects in the developing fetus.
- TCE may also affect the immune system – this includes changes to the developing immune system in early life.
- Exposure to TCE may also increase the risk of certain types of cancer (kidney, liver, and non-Hodgkin's lymphoma) based on studies in workers or animals breathing very high levels of TCE - thousands of times greater than what may be found at vapor intrusion sites.
When chemical vapors enter buildings from vapor intrusion, the amount in indoor air is typically not high enough to affect most people's health. The possible health effects from breathing PCE depends on the levels in indoor air and how long people breathe it.
- At high levels in the workplace, PCE can cause neurological effects such as vision changes or delayed reaction time.
- Exposure to PCE may increase the risk of certain types of cancer (bladder cancer, non-Hodgkin's lymphoma, multiple myeloma, liver cancer, and leukemia) based on studies in workers or animals breathing very high levels of PCE - thousands of times greater than what may be found at vapor intrusion sites.
For more information
For health-related questions regarding vapor intrusion or contaminated sites, please contact us.
Prepared in cooperation with the US Agency for Toxic Substances and Disease Registry.