Range cf Radiation Levels (migroroentgens/hr) Location Mean Annual Dose (millirads)* Average Pressure (inches Hg) Atypical Radiation Levels (microrcentgens/hr) Harrisburg, Pa. 9.6-11.9 (2) e8 29.8 - Pittsburgh, Fe. 9.8 - 13.$ (3) $6 29.2 - Cleveland, Chio 10.5 - 11.8 (2) Lie 29.4 Toledo, Ohio 8.7 - 10.0 (2) BA) 29.5 14.9 (over granite Chicago, Ill. 16.3 - 11.6 (4) 83 294 17.0 (adjacent to paving stone} < U.8. Post Office Bldg. of granite construction) - 10.1 - 10.4 (3) ob 29.1 9.1 - 12.5 (3) 92 29.3 - Sioux Falls,S. Dekota 11.5 - 11.8 (2) 95 28.8 - Cheyenne, Wyo. 17.2 - 17.6 (2) 142 24.k - Denver, Colo. 16.6 - 19.4 (10) 147 25.0 Madison, Wisc. Minneapolis-St. Paul, Minn. 22.4 (between U.S. Mint and City and County Bligs.) Colorado Springs, Colo. 19.3 - 22.3 (4) 168 2h 2 Grand Junction, Colo. 15.7 - 18.4 (3) 138 25.5 - Albuquerque, N. Mexico 13.8 - 14.5 (4) 116 25.2 - Amarillo, Texas 12.9 - 13.6 (4%) 1¢8 26.4 - 9.9 - 10.5 (4) 4 28.7 - Tulsa, Okla. 10.8 - 11.6 (4) 92 29.3 - Little Rock, Ark. 12.8 - 13.3 (2) 106 29.7 - 9.4-11.0 (2) 83 29.8 11.1 - 12.3 (2) 95 29.6 13.3 (near brick apartment house) 14.8 (near brick-faced Oklahoma City, Okla. Memphis, Tenn. Chattsnooga, Tenn. - motel units } 16.1 (on narrow business street; 8th between Broad and Market) * Pose in soft tissue, assuming constant dose rate. iL rad = 100 ergs/gm, 1 microroentgen/hr = 8.152 mrad/yr. Table I. Environmental radiation levels measured in principal United States cities during August, 1957. The number of observaticns for each range are shows in parentheses. Blevatz* valiaviczs Levels preduced by lecalics*? sources sr2 shown in the least column. 6 = . ee 2 . a te are ~ OTL « nS =A “ SS mene . Oe . ORAN . esg "eT we . . 1G. .- ES s .. = . Sy ms = ey =& 2 _ ™ " OES ES ~~ ‘ = * a ow,SS rs “ ~ y . . ae germ oN eneOCT rates engvaytenceygeeepgm CSSLOE eee Oo eee Gigmgrs PTT TREE OF QA “ _s ~~ oy TR ER es = Ss ~ =A, “Saal - = ee

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