Health hazards associated with elevated levels of indoor radon--Pennsylvania.

As a part of the safety program at the Limerick Nuclear Power Plant in Pennsylvania, per­ sonnel entering the plant must pass through a radiation monitoring area. In December 1984, the monitoring device detected an abnormally high level of radiation in one construction worker. When an investigation was made to determine how and where this worker was being exposed to excessive radiation, investigators found that the air in the man's home contained extremely high levels of "radon daughters," the short-lived decay products of radon-222. Radon is an inert, radioactive gas formed in the decay chain of uranium-238. For each year the worker and his family lived in this house, they were exposed to over 50 times the annual occupational limit of exposure for uranium miners. The family relocated until remedial actions to lower the indoor radon levels could be completed. As a result of this incident, in January 1985 state officials in Pennsylvania began a sam­ pling program in which over 2,000 homes around the construction worker's house were examined. The homes are in an area of natural uranium deposits. Approximately 40% of the homes had radon levels exceeding the U.S. Environmental Protection Agency (EPA) guideline for indoor radon of 0.02 "working levels." A working level is a measure of radon daughter concentrations and is defined as any combination of radon daughters in 1 liter of air that re­ sults in 1.3 x 105 million electron volts of potential alpha energy. About 7% of the homes tested had radon levels at or above the 0.1 working level. If residents in these homes spend 75% of their time indoors exposed to 0.1 working level, their yearly exposure would equal 4 working level months, the annual occupational limit of exposure. A working level month is a measure of exposure and is a function of the time of exposure and the level of radon daugh­ ters, given in working levels. Reported by J Logue, DrPH, J Fox, MD, Pennsylvania Dept o f Health; Cancer Br, Div of Chronic Disease Control, Center for Environmental Health, CDC. Editorial Note: The elevated radon levels near the eastern border of Pennsylvania are asso­ ciated with natural uranium deposits that extend into northern New Jersey and southern New York. Since similar geologic deposits are found throughout the country, the elevated radon levels in Pennsylvania may indicate a much broader national problem. Radon enters a building