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EPA Investigation Finds High Vapor Levels

August 2006 fact sheet

U.S. Environmental Protection Agency's investigation of chemical pollution underneath sections of Troy found elevated levels of fumes are seeping into some buildings, but the Agency and its state and local partners are now considering ways to solve the problem and protect people's health. The EPA study this summer confirmed a city of Troy investigation last spring that found vapors given off from contaminated underground water were moving into schools, a church, the city police station and several homes. This June Ohio EPA asked EPA's emergency response branch for help in dealing with the vapor intrusion problem. Health officials believe the fumes aren't strong enough to cause health problems in the short term, but over the long run something will need to be done to head off potential sickness.

EPA sampled 15 locations in Troy looking for gas that might be present in the soil underneath the buildings. This type of testing is called sub-slab sampling. It is more reliable than simply taking indoor air samples because common consumer products such as paint and cleaners give off small amounts of fumes that could affect sampling results. At 10 of the 15 sampling locations EPA found soil-vapor concentrations that do not meet health standards set by Ohio Department of Health. The 10 locations of concern include two schools, a church, the police station and six homes.

Chemical called PCE

The contamination comes from a chemical called tetrachloroethylene, more commonly known as PCE. It is in a class of chemicals called volatile organic compounds or VOCs, which are made from petroleum and easily produce vapors. PCE is used in dry cleaning and as an industrial degreaser. In 2004, Ohio EPA discovered PCE had soaked through the ground and got into underground water supplies (called ground water in environmental terms) and had formed a mass or plume of contamination. The PCE carried along in the slow-moving plume is giving off vapors that move to the surface. The PCE fumes can seep through cracks, holes and pipes in building foundations.

Representatives from EPA, Ohio EPA and Ohio Department of Health briefed school, church and city officials as well as residents in the affected homes and the media about the vapor intrusion problem. At high concentrations or over a long period of time, breathing PCE fumes can cause health problems.

Residents of highly industrialized countries such as the United States daily come in contact with chemicals. People can get sick from chemical exposure, but getting sick depends on several factors. One of these is how much of the chemical enters the body. Other important factors are how long or how often a person is exposed to the pollutant. And general health, age and lifestyle also play a role in whether sickness will happen from chemical exposure.

The latest sampling showed PCE vapor levels won't cause immediate illness, but are high enough to be of future concern. EPA, state and local officials are studying various short- and long-term options for fixing the problem.


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