Environmental levels of penetrating ionizing radiation were measured in the lower Arkansas and White River valleys of Arkansas. Measurements of environmental gamma and cosmic rays were made using a portable high pressure ionization chamber. The surveyed area encompassed a large coal-fired industrial plant. Observed exposure rates ranged from 5.9 microRoentgens per hour (μR/h) to 13.4 μR/h. The average exposure rate for the region was 8.8 μR/h. This value corresponds to 77 millirem (mrem) or 0.77 milliSieverts (mSv) per year. In comparison, a prior state-wide survey reported an average dose equivalent rate of 78.2 mrem (0.782 mSv) per year in Arkansas.
Epperson, C. E.; Meiners, S.; and Swindle, D.
"Penetrating Ionizing Radiation Levels Observed in the Lower Arkansas and White River Valleys of Arkansas,"
Journal of the Arkansas Academy of Science: Vol. 40
, Article 11.
Available at: http://scholarworks.uark.edu/jaas/vol40/iss1/11