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Epidemiologic Notes and Reports Employee Illness from Underground Gas and Oil Contamination -- Idaho

The National Institute for Occupational Safety and Health (NIOSH) recently completed an evaluation of an office building in Boise, Idaho, in which workers were experiencing symptoms of headache and nausea related to intermittent noxious odors (1). The cause of the problem was gasoline vapors entering the building from an underground aquifer contaminated with petroleum products leaking from a nearby oil storage tank.

The affected employees worked in the basement of a five-story medical office building and had been experiencing the symptoms--which in one case included vomiting--intermittently for 10 months. The symptoms were occasionally associated with a petroleum odor that the NIOSH investigator found coming through cracks in the floor and the joints at which the floor met the foundation and the support pillars connected to the floor. Laboratory analysis confirmed the source of the odor as gasoline. The vapor concentrations at the cracks and inside one wall were above the lower explosive limit for gasoline of 14,000 ppm, and the vapor concentrations in the rooms ranged up to 280 ppm.

To determine the source of the contamination, six test holes were drilled around the building, A water sample from one of these holes had petroleum products floating on the surface. An evaluation has determined a large gas and oil tank farm, located two blocks from the building, is the source of the water table contaminants.

Based on recommendations by the NIOSH investigator, immediate steps were taken to correct the hazards. All accessible cracks and joints have been sealed, and the building ventilation system has been adjusted to pressurize the building relative to the outside air. Since these corrections were made, petroleum-product vapors are no longer detectable, and the employees' symptoms have ceased. Reported by the Hazard Evaluations and Technical Assistance Br, Div of Surveillance, Hazard Evaluations, and Field Studies, NIOSH Region X, CDC.

Editorial Note

Editorial Note: The employees' symptoms are consistent with the gasoline vapor concentrations found in the building and with the higher concentrations that probably existed intermittently in the past.

NIOSH has evaluated or is currently evaluating over 100 complaints of various symptoms among office employees. Although a large majority of these evaluations have found that the complaints derive from inadequate office ventilation, occasionally symptoms can be linked to substances measured in the environment, e.g., fibrous glass (2), fumes from spirit duplicators (3), and emissions from urea-formaldehyde foam insulation (4). In the Idaho situation, prompt correction was required to prevent a possible explosion of gasoline vapors. Although such situations are unusual, building occupants in areas near petroleum storage facilities (including gasoline service stations) should be alert to the possibility of environmental contamination--particularly of the water table by petroleum products.


  1. Apol A. Health hazard evaluation--Boise, Idaho. Cincinnati: National Institute for Occupational Safety and Health, 1982. (Report no. HETA 82-062-1077).

  2. Tharr D. Health hazard evaluation--Schenectady, New York. Cincinnati: National Institute for Occupational Safety and Health, 1980. (Report no. TA 80-080).

  3. Apol A. Health hazard evaluation--Everett, Washington. Cincinnati: National Institute for Occupational Safety and Health, 1980. (Report no. TA 80-032).

  4. Gunter, B. Health hazard evaluation--East Helena, Montana. Cincinnati: National Institute for Occupational Safety and Health, 1981. (Report no. HETA 81-108-883).

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