Figure 9.2 Radon risk in the United StatesCASE STUDIES
READING PRONG: A particularly uranium-rich geological formation,
called the Reading Prong (or Highlands area), stretches from Pennsylvania
through northwestern New Jersey into southern New York. Rocks in the
Reading Prong are mostly granites, are very old (almost one billion years),
and contain high concentrations of uranium. Testing of homes built along this
geologic formation has revealed high indoor levels of radon gas. In New
Jersey, where concern has centered on about 250,000 homes and other
buildings on top of the Reading Prong, uranium lies under much of the
northern half of the state, an area with 1.6 million buildings. Furthermore,
glacial debris from the last ice age tends to be very thick in this area, which
can prevent radon gas from escaping to the surface prior to its breakdown into
another radioactive element.