Distribution of indoor radon concentrations in Pennsylvania, 1990-2007

Scientific Investigations Report 2013-5143



Results from 548,507 indoor radon tests from a database compiled by the Pennsylvania Department of Environmental Protection, Bureau of Radiation Protection, Radon Division, are evaluated in this report in an effort to determine areas where concentrations of radon are highest. Indoor radon concentrations were aggregated according to geologic unit and hydrogeologic setting for spatial analysis. Indoor radon concentrations greater than or equal to the U.S. Environmental Protection Agency (USEPA) action level of 4 picocuries per liter (pCi/L) were observed for 39 percent of the test results; the highest concentration was 1,866.4 pCi/L.

When analyzed according to Pennsylvania’s geologic units, 93 of the 188 (49.5 percent) geologic units with indoor radon concentrations had median concentrations greater than the USEPA action level of 4 pCi/L; most of these geologic units are located in the eastern part of the State and include metamorphic rocks, limestones, sandstones, shales, and glacial deposits. When analyzed according to Pennsylvania’s hydrogeologic settings, 5 of the 20 (25 percent) settings had median indoor radon concentrations greater than the USEPA action level of 4 pCi/L; these settings are located mostly in the south-central part of the State.

Median indoor radon concentrations aggregated according to geologic units and hydrogeologic settings are useful for drawing general conclusions about the occurrence of indoor radon in specific geologic units and hydrogeologic settings, but the associated data and maps have limitations. The aggregated indoor radon data have testing and spatial accuracy limitations due to lack of available information regarding testing conditions and the imprecision of geocoded test locations. In addition, the associated data describing geologic units and hydrogeologic settings have spatial and interpretation accuracy limitations, which are a result of using statewide data to define conditions at test locations and geologic data that represent a broad interpretation of geologic units across the State. As a result, indoor air radon concentration distributions are not proposed for use in predicting individual concentrations at specific sites nor for use as a decision-making tool for property owners to decide whether to test for indoor radon concentrations at specific property locations.

Study Area

Publication type Report
Publication Subtype USGS Numbered Series
Title Distribution of indoor radon concentrations in Pennsylvania, 1990-2007
Series title Scientific Investigations Report
Series number 2013-5143
DOI 10.3133/sir20135143
Year Published 2013
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Pennsylvania Water Science Center
Description Report: viii, 31 p.; PARnGeo: Zip file; PARnHydroGeo: Zip file
Time Range Start 1990-01-01
Time Range End 2007-12-31
Country United States
State Pennsylvania
Projection Albers Equal-Area Conic
Scale 100000
Online Only (Y/N) Y
Additional Online Files (Y/N) Y
Google Analytic Metrics Metrics page
Additional publication details