Indoor radon levels in the northeastern U.S.: effects of energy-efficiency in homes.

The expectation of elevated 222Rn levels in modern homes that have low air interchange rates with the out-of-doors caused us to survey both solar and conventional homes in northeastern New York State. The solar homes as a group have three times the 222Rn levels of the conventional homes, and specific problems exist that are introduced or exaggerated by modern construction. For example the highest two levels of radon in the solar homes give radiation doses over 30 yr that are known to produce lung cancer in 1% of uranium miners. Summer readings in more than half of the cases are different from winter ones by a factor of two or more, so that year-round measurements are necessary for precise dosimetry. The track etching technique is ideally suited for such measurements.