PA Radon Story
The Pennsylvania Radon Story
by Thomas M. Gerusky
In December 1984, the Pennsylvania Bureau of Radiation Protection found itself confronted with the discovery of a home in eastern Pennsylvania having the highest level of radon daughters ever reported. The Bureau responded with a massive radon monitoring, educational, and remediation effort. As of November 1986, over 18,000 homes had been screened for radon daughters; of which, approximately 59% were found to have levels in excess of the 0.020 Working Level guideline. Pennsylvania's response to the indoor radon problem is detailed in this article.
As with most state radiation control programs, Pennsylvania recognized that naturally occurring radon gas was a potential indoor air pollution problem in geologic areas with elevated levels of uranium ore. It was also recognized that other states had already been working to resolve the problem for specific areas in their respective states. It was generally believed that the most significant problems were located in areas where man had enhanced the uranium environment, such as the Grand Junction area of Colorado where uranium mill tailings had been used for fill around newly constructed or remodeled buildings.
Elevated levels of radon were also reported from other areas of the country. Florida had a serious problem on phosphate lands, Montana had detected elevated levels in the Butte area, and Pennsylvania and other states had experienced elevated radon levels in the vicinity of uranium and radium extraction facilities. The U.S. Department of Energy had designated certain sites for decontamination and remedial action at facilities operated for the federal government during and after the Manhattan Project days.
In the late 70's, Pennsylvania Power and Light Company, a utility operating in central Pennsylvania carried out a study involving radon measurements in homes of their employees to determine if weatherization programs were effective. Radon was selected because of the relative ease of measurement. To their surprise, elevated radon levels were found in some homes, but there appeared to be no correlation between radon levels and home construction or location. The data were reported to the Pennsylvania Bureau of Radiation Protection (Bureau), and plans were made to begin a pilot project to determine radon levels in other areas of the state. The March 1979 Three Mile Island accident caused a major change in Bureau priorities and the survey was placed on the back burner. Plans were again made in 1984 to begin a modest survey program in the 1985-86 fiscal year as outlined in the annua1 budget submitted to the Pennsylvania General Assembly by Governor Thornburgh.
We did not have to wait that long. In December 1984, the Bureau received a telephone call from the Health Physicist at the Limerick Nuclear Generating Station informing us that a construction worker at their still incomplete plant was setting off alarms when he attempted to enter the plant through portal radiation monitors. Since the plant was not yet generating fission products, health physicists from the utility and their consultant performed a radiation survey in the home of the individual and found very high levels of radon daughters throughout the structure. Radon daughter levels (concentration of decay products of radon in the uranium chain) ranged up to 13 Working Levels (WL) or 2600 pCi/ L of radon gas.
Numerous resurveys verified those findings, and estimates of exposure and risk of lung cancer were attempted. A search of the literature on radon and radon daughter concentrations in residential structures made us aware that this was the highest level ever found in a private residence. The National Council on Radiation Protection and Measurements (NCRP) had issued two reports on radon and radon daughter exposures in April 1984, and these two documents were used to estimate the exposures of the residents of the home. The dose equivalent rate to the bronchial epithelium of the lung from continuous exposure to radon daughter concentrations of 13 WL was calculated to be 9100 rem annually. The risk of lung cancer from continuous exposure to 13 WL in one year is 0.13 or 13 chances out of 100.
A decision was made to officially recommend that the occupants vacate the residence, and a formal recommendation was made by a hand-carried letter signed by the Secretary of Pennsylvania Department of Environmental Resources. The Philadelphia Electric Company and Bechtel, Inc., the contractor employing the individual, assisted in providing living arrangements for the family until remedial action could be taken in the home.
Assuming this was not an isolated case, the Bureau designed a house-to-house campaign to evaluate radon levels in the immediate neighborhood. Unfortunately, there were and are no standards for exposure to radon or radon daughters for the general population. NCRP recommends an annual exposure guideline of 2 WL Months/yr., which corresponds to a continuous exposure guideline of 0.04 WL. Other guidelines have also been used. The Environmental Protection Agency (EPA), with assistance from the Centers for Disease Control (CDC), has recommended remedial action at 0.02 WL. The Pennsylvania Department of Health requested assistance from CDC in determining such guidance. One WLM per year or 0.02 WL continuous occupancy was received as guidance, with a sliding time scale for remedial action based upon levels detected. More information can be found on the Pa. DEP website.
we take time
We take extra time to explain how your home works.