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EPA Works with Local Agencies, Residents to Analyze Indoor Air Problems in Basements

Release Date: 10/09/2009
Contact Information: EPA Region 7 - David Bryan, 913-551-7433,; City of Wichita Environmental Services Department - D. Kay Johnson, 316-268-8351,

Environmental News


(Kansas City, Kan., October 9, 2009) - The U.S. Environmental Protection Agency (EPA) will be working with residents in four Kansas counties to check potential oxygen depletion issues in the basements of their homes. Oxygen depletion can occur when carbon dioxide, methane or other soil vapors seep into building spaces, especially basements.

EPA officials became concerned amid reports of carbon dioxide and methane vapors discovered in homes by local emergency and health officials after several major rainfall events in the area. Recent reports of possible methane and carbon dioxide intrusion increased the level of concern for public health and safety and EPA felt it important that the public be notified. The reports center on cases in Sedgwick and Butler counties with single cases reported in Sumner and Harper counties.

Elevated carbon dioxide and methane levels can deplete oxygen levels in indoor air resulting in an immediate and a possible long-term health hazard. High-level methane concentrations can create immediate safety concerns with explosive conditions.

Because carbon dioxide is odorless and colorless, families living in homes affected by high concentrations typically aren’t aware of the problem immediately. They often learn of the problem only as a result of physical ailments (labored breathing, headaches, exhaustion) or trouble starting or maintaining a flame with a pilot light. Prolonged exposure to high concentrations can result in unconsciousness and asphyxiation. An area is considered oxygen-deficient when the oxygen content goes below 19.5 percent.

In general, the higher the carbon dioxide levels in a building, the lower the amount of fresh air exchange. Examining carbon dioxide levels in indoor air can reveal if the heating, ventilation and air conditioning systems are operating within guidelines.

Problems with re-lighting gas pilot lights at residences following localized flooding in September 2008 prompted residents to contact health and safety officials who initially discovered high concentrations of carbon dioxide in homes.

EPA is conducting two separate sampling and research activities in the area. EPA Region 7 hopes to collect ground water and soil vapor samples from properties in Sedgwick, Butler, Harper and Sumner counties where residents have reported incidents of oxygen depletion. The samples will be analyzed in an effort to determine if there are chemical pollutants or contamination in the ground water and soil that may be causing or contributing to the problem. EPA’s authority in this instance only extends to a situation where chemical contamination is the source of the problem. Region 7 representatives and contractors are working to obtain access to properties where they want to sample. Once access to the properties is obtained and samples are collected, results will be provided to residents within 60 days after a detailed analysis is completed.

EPA first became involved after City of Wichita Environmental Services Department officials contacted EPA’s National Risk Management & Research Lab (NRMRL) in Ada, Okla., in October 2008 for assistance in identifying the source of carbon dioxide intrusion. The lab has since worked with the City of Wichita, Sedgwick County, and the Kansas Department of Health & Environment to research the issue. There appears to be little or no published research on oxygen depletion and carbon dioxide buildup in homes due to gas intrusion.

EPA NRMRL scientists began conducting a carbon dioxide intrusion/oxygen depletion study in the Prairie Lakes Addition in Valley Center, Kan., in August. The study is designed to evaluate the depletion of oxygen and intrusion of gases into buildings as a result of manmade or natural factors. They believe real-time carbon dioxide monitoring will provide data that helps evaluate the potential threat to human health. Three residents have given permission to the research team to place monitoring and radon or vapor remediation equipment in their homes.

During periods of extremely heavy rainfall and flooding, the surface of the ground can become sealed off with water or shallow ground water levels may rise. Soil gases that would normally seep into the air outside can instead be forced into basements through cracks in walls, floors or foundations, service lines or sump pump exposure. Under these circumstances, the level of oxygen can be reduced by the rising levels of soil gases.

The best short-term remedy for stopping soil gas vapors intruding into building is to fill cracks, joints, gaps and openings in walls, floors, suspended floors and around service lines with an impermeable seal such as polyurethane caulk or hydraulic cement.

Other steps residents may take include:

  • Do not sleep in basements that are experiencing even mild flooding. During mild flooding conditions, open windows or doors to allow circulation of fresh outdoor air into the basement.
  • Wall-mounted fixed oxygen and carbon dioxide gas analyzers can be installed, particularly in basements, to check oxygen depletion in the residence. This option can be expensive with top-quality instruments costing up to $2,000.
  • To prevent excessive soil gases from entering a building, the homeowner can purchase and install a radon reduction or vapor reduction system. The radon system draws air from beneath the home and vents the air outdoors. This is still being researched.

Residents who believe they might have an immediate health or safety issue should contact 911 immediately.

General questions regarding decreased oxygen levels in residences and other indoor environmental quality issues can be directed to Becky Lewis, City of Wichita Environmental Services Department, at 316-268-8355; or Randy Duncan, Sedgwick County Emergency Response, at 316-660-5959.

Persons with questions about EPA activities should contact Dianna Whitaker, EPA Region 7 Community Involvement Coordinator, 913-551-7598, or toll free 1-800-223-0425. Technical questions regarding the chemical sampling should be directed to Katy Miley, EPA Region 7, at 913-551-7916.