The report represents technical guidance based on the results of the EPA tests and documented tests by other research groups on actual houses with elevated indoor radon levels, and is intended to supply radiological health officials, building contractors, and concerned homeowners with information on how to modify houses to reduce indoor radon. Introductory information is provided on sources of indoor radon, the health effects of radon exposure, methods for measuring radon levels, and how radon enters and builds up in house air. Nine methods for reducing indoor radon in detached houses are described: natural and forced-air ventilation, forced-air ventilation with heat recovery, active avoidance of house depressurization, sealing major radon sources, sealing radon entry routes, drain-tile soil ventilation, active ventilation of hollow-block basement walls, and sub-slab ventilation. For each method, information is presented on principle of operation, applicability, how much confidence one can have that the method can achieve radon reduction, and an estimate of installation costs.

Shipping list no.: 86-737-P. "June 1986." Includes bibliographical references (pages 49-50). "EPA/625/55-86/019."