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Radon School Survey in North Dakota 1989-1992

INTRODUCTION

Background

During the period 1989 to 1992, the North Dakota State Department of Health and Consolidated Laboratories (NDSDHCL) offered to test for radon in 383 school districts. Three hundred eighty-three represents all public and private nonprofit schools, grades K through 12 in North Dakota. Of the 383 districts, 217 districts chose to participate.

Sampling

The Department followed EPA guidance for sampling protocol. Ten percent of school rooms were provided duplicate samples and every twentieth room received a control sample.

School districts submitted plans and sketches of their facilities to the Department. Department personnel approved the selections of sampling sites. Classrooms that were utilized the most were given the highest priority.

The database contained 9,748 samples from 217 school districts. The number of school districts not represented in this survey was 166. Many samples were lost, not analyzed, or were refused.

The following types and numbers of samples were deleted from the original database:

Controls         412
Duplicate        906 
TOTAL          1,318

The final database contained 879 official duplicate samples and
7,551 regular samples for a total of 8,430 samples.

                               217 
 % school district recovery =  --- x 100 = 56.4%
                               383

                                101,664
% school population recovery =  ------- x 100 = 86.4%
                                117,719

Discussion

This survey was voluntary and, in certain counties, none of the school districts submitted any samples. These counties were: Foster, Griggs, Sheridan, and Slope. Some of the school districts in these counties began testing, using commercial vendors, before the Department began its survey. They were offered free testing by the Department but chose not to participate.

The county percentage of samples whose concentration is greater than 4 picocuries per liter is shown in Table 11, whereas the city/county statistical summary is presented in Table 12.

TABLE 10

SCHOOL SURVEY STATISTICS BY PARAMETER


                                                                       
             NUMBER       PERCENT                 ARITHMETIC    PERCENT OF SAMPLES   
               OF           OF       ARITHMETIC   STANDARD        GREATER THAN:                                             
FLOOR        SAMPLES      SAMPLES       MEAN      DEVIATION     4 pCi/l      20 pCi/l                                             
                                
    B           260          3.1         2.8         4.1          16.2           1.5      

    1         8,165         96.9         1.8         2.4           7.4           0.3      

    2             5          0.1         2.7         1.9          20.0           0.0      

   All        8,430        100.0         1.8         2.5           7.7           0.3         



Two different companies were employed by the NDSDHCL to test radon in North Dakota schools. Home Radon Detection, Inc. (HRDI) of Grayslake, Illinois tested 7,543 samples. HRDI utilized a charcoal canister for a 48hour test period.

Radon Testing Corporation of America (RTCA) of Irvington, New York tested 2,121 samples using a charcoal canister with a diffusion barrier for 7 days.

Quality Assurance

The average radon concentration for the 412 controls was 0.2 pCi/l with a standard deviation of 0.4. The precision was determined by utilizing a coefficient of variation computer program. Some variations were quite large and may indicate an error in labeling, etc. The average coefficient of variation was 17.86% which indicates the data may have had poor precision. No accuracy samples were taken during this survey.

Figure 3 indicates the data is lognormal at higher concentrations. The comparison of schools to the other surveys may be found in Figure 8.

FIGURE 4 - SCHOOL ROOM RADON STUDY 1989-1992

School Graph

Number of samples: 8430

Summary and Conclusions

This survey has shown that of the school rooms tested, the maximum concentration was 66.2 pCi/l. The percentage of rooms with concentrations greater than 4 pCi/l or 20 pCi/l are 7.7% and 0.3%, respectively. The mean radon concentration for 8,430 samples was 1.8 pCi/l with a standard deviation of 2.5.

TABLE 11

SCHOOL SURVEY STATISTICS BY COUNTY


                                                               PERCENTAGE       PERCENTAGE        
                NUMBER                        ARITHMETIC        OF SAMPLES       OF SAMPLES        
                  OF          ARITHMETIC      STANDARD         GREATER THAN     GREATER THAN      
COUNTY         SAMPLES           MEAN         DEVIATION           4 pCi/l         20 pCi/l         

Adams             52             2.2             1.9                5.8              0.0          

Barnes           135             2.2             1.6                9.6              0.0          

Benson            83             1.9             1.4                4.8              0.0          

Billings          37             2.7             2.1               18.9              0.0          

Bottineau         72             0.7             0.5                0.0              0.0          

Bowman           101             2.5             2.9               21.8              0.0          

Burke             18             1.2             0.7                0.0              0.0          

Burleigh         615             1.0             0.9                1.5              0.0          

Cass            1102             1.6             2.0                6.2              0.2          

Cavalier         102             1.2             0.8                0.0              0.0          

Dickey            59             1.7             3.0               10.2              1.7          

Divide            50             0.5             0.4                0.0              0.0          

Dunn              45             1.1             0.9                2.2              0.0          

Eddy              37             1.6             1.5                5.4              0.0          

Emmons           116             2.3             1.8               14.7              0.0          

Golden            75             1.0             0.6                0.0              0.0          
 Valley                                                                                           

Grand            706             1.3             1.4                5.0              0.0          
 Forks                                                                                            

Grant             42             3.3             3.4               42.9              0.0          

Hettinger         43             4.4             3.3               34.9              0.0          

Kidder            48             2.4             1.7               14.6              0.0          

Lamoure           43             2.3             3.0                7.0              2.3          

Logan             75             1.2             0.8                1.3              0.0          

McHenry          166             1.3             1.7                7.2              0.0          

McIntosh         116             2.5             1.4               13.8              0.0          

McKenzie         113             2.0             1.1                2.7              0.0          

McLean           193             1.8             1.6                8.3              0.0          
Mercer           279             1.7             1.1                3.9              0.0          

Morton           320             1.6             1.6                5.0              0.0          

Mountrail        172             1.2             1.1                2.3              0.0          

Nelson            67             1.8             1.5                6.0              0.0          

Oliver            43             1.7             1.2                4.7              0.0          

Pembina          128             2.2             2.8               17.2              0.0          

Pierce            63             1.5             0.9                0.0              0.0          

Ramsey           169             1.8             1.5               11.8              0.0          

Ransom           103             5.0             4.2               49.5              1.0          

Renville          99             1.1             0.8                0.0              0.0          

Richland         160             1.4             2.0                6.9              0.0          

Rolette          136             1.1             1.1                3.7              0.0          

Sargent           98             2.9             3.2               27.6              0.0          

Sioux             50             1.8             0.9                2.0              0.0          

Stark            389             4.5             6.2               21.6              4.6          

Steele            28             0.9             0.8                0.0              0.0          

Stutsman         283             2.0             2.0               10.6              0.0          

Towner            97             1.0             0.7                0.0              0.0          

Traill           162             2.1             3.5                6.8              1.2          

Walsh            205             3.0             5.8               19.0              2.0          

Ward             845             1.3             1.2                2.8              0.0          

Wells             55             1.1             1.0                0.0              0.0          

Williams         235             1.8             1.7                4.3              0.0          



TABLE 12

SCHOOL SURVEY STATISTICS BY CITY/COUNTY


                                                                        PERCENT       PERCENT       
                                                                        SAMPLES       SAMPLES       
                              NUMBER                      ARITHMETIC    GREATER       GREATER       
                                OF          ARITHMETIC    STANDARD       THAN          THAN         
COUNTY         CITY           SAMPLES          MEAN       DEVIATION     4 pCi/l       20 pCi/l      

Adams                           52             2.15          1.86          5.8           0.0        

             Hettinger          38             1.46          0.76          0.0           0.0        

             Reeder             14             4.04          2.53         21.4           0.0        

Barnes                         135             2.17          1.65          9.6           0.0        

             Valley City       111             1.89          1.62          5.4           0.0        

             Wimbledon          24             3.51          0.97         29.2           0.0        

Benson                          83             1.86          1.40          4.8           0.0        

             Esmond             20             1.57          0.88          5.0           0.0        

             Fort Totten        31             1.22          1.33          6.4           0.0        

             Leeds              32             2.66          1.34          3.1           0.0        

Billings                        37             2.72          2.09         18.9           0.0        

             Fryburg            11             1.92          0.55          0.0           0.0        

             Medora             26             3.06          2.39         26.9           0.0        

Bottineau                       72             0.73          0.49          0.0           0.0        

             Bottineau          72             0.73          0.49          0.0           0.0        

Bowman                         101             2.49          2.87         21.8           0.0        

             Bowman             70             2.12          2.19         18.6           0.0        

             Rhame               8             9.54          1.95        100.0           0.0        

             Scranton           23             1.17          0.94          4.3           0.0        

Burke                           18             1.19          0.66          0.0           0.0        

             Bowbells           18             1.19          0.66          0.0           0.0        

Burleigh                       615             1.05          0.93          1.5           0.0        

             Bismarck          609             1.01          0.84          1.0           0.0        

             McKenzie            3             2.77          0.17          0.0           0.0        

             Menoken             3             6.50          0.86        100.0           0.0        

Cass                          1102            1.63          1.96           6.2         0.2      

             Amenia              3            1.63          0.05           0.0         0.0      

             Argusville         25            0.72          0.52           0.0         0.0      

             Casselton          52            3.67          2.73          40.4         0.0      

             Davenport          26            3.09          1.09          19.2         0.0      

             Fargo             653            1.84          2.16           5.8         0.3      

             Hunter             24            1.48          1.19           8.3         0.0      

             Kindred            84            0.80          0.76           1.2         0.0      

             Mapleton           10            1.64          0.28           0.0         0.0      

             West Fargo        225            0.83          0.78           0.4         0.0      

Cavalier                       102            1.21          0.77           0.0         0.0      

             Langdon            76            0.82          0.39           0.0         0.0      

             Munich             26            2.33          0.43           0.0         0.0      

Dickey                          59            1.70          2.97          10.2         1.7      

             Ellendale          22            1.92          1.46           9.1         0.0      

             Oakes              37            1.57          3.58          10.8         2.7      

Divide                          50            0.51          0.37           0.0         0.0      

             Crosby             50            0.51          0.37           0.0         0.0      

Dunn                            45            1.14          0.88           2.2         0.0      

             Dodge               5            2.22          0.28           0.0         0.0      

             Killdeer           40            1.01          0.83           2.5         0.0      

Eddy                            37            1.59          1.47           5.4         0.0      

             New Rockford       37            1.59          1.47           5.4         0.0      

Emmons                         116            2.27          1.79          14.7         0.0      

             Braddock            8            1.19          0.41           0.0         0.0      

             Hague               7            5.77          0.61         100.0         0.0      

             Hazelton           24            1.85          0.83           0.0         0.0      

             Linton             48            1.40          1.28           6.3         0.0      

             Strasburg          29            3.49          1.82          24.1         0.0      

Golden                          75            1.04          0.64           0.0         0.0      
 Valley                                                                                         

             Beach              61            1.16          0.64           0.0         0.0      

             Golva              14            0.51          0.28           0.0         0.0      

Grand                          706            1.31          1.45           5.0         0.0      
 Forks                                                                                          

             Grand Forks       574            1.07          1.26           2.3         0.0      

             Larimore           50            1.60          1.13           8.0         0.0      

             Manvel             19            1.74          0.58           0.0         0.0      

             Northwood          28            3.24          1.67          39.3         0.0      

             Thompson           35            2.96          2.28          20.0         0.0      

Grant                           42            3.27          3.36          42.9         0.0      

             Carson             15            0.64          0.28           0.0         0.0      

             New Leipzig        17            4.68          4.28          47.1         0.0      

             Raleigh            10            4.81          0.12         100.0         0.0      

Hettinger                       43            4.38          3.28          34.9         0.0      

             Mott               22            3.73          3.71          27.3         0.0      

             Regent             21            5.07          2.59          42.9         0.0      

Kidder                          48            2.38          1.67          14.6         0.0      

             Pettibone          15            2.83          1.23          20.0         0.0      

             Tappen             17            1.00          0.48           0.0         0.0      

             Tuttle             16            3.44          1.85          25.0         0.0      

Lamoure                         43            2.28          3.02           7.0         2.3      

             Kulm               25            2.56          3.90          12.0         4.0      

             Verona             18            1.90          0.65           0.0         0.0      

Logan                           75            1.20          0.83           1.3         0.0      

             Gackle             30            0.55          0.33           0.0         0.0      

             Lehr                4            1.13          0.16           0.0         0.0      

             Napoleon           41            1.69          0.80           2.4         0.0      

McHenry                        166            1.13          1.67           7.2         0.0      

             Deering             7            1.31          0.24           0.0         0.0      

             Drake              14            1.07          0.43           0.0         0.0      

             Granville          36            0.85          0.46           0.0         0.0      

             Towner             43            0.55          0.32           0.0         0.0      

             Upham              14            0.89          0.57           0.0         0.0      

             Velva              52            2.51          2.53          23.1         0.0      

McIntosh                       116            2.49          1.39          13.8         0.0      

             Ashley             44            3.10          0.86          18.2         0.0      

             Wishek             49            1.66          1.58          10.2         0.0      

             Zeeland            23            3.10          0.65          13.0         0.0      

McKenzie                       113            2.02          1.14           2.7         0.0      

             Alexander          31            2.15          1.77           9.7         0.0      

             Cartwright          3            1.53          0.09           0.0         0.0      

             Sidney              2            3.80          0.00           0.0         0.0      

             Watford City       77            1.95          0.74           0.0         0.0      

McLean                         193            1.75          1.57           8.3         0.0      

             Butte              21            1.18          0.90           0.0         0.0      

             Garrison           37            1.89          2.23          16.2         0.0      

             Max                33            1.24          0.49           0.0         0.0      

             Turtle Lake        37            1.43          0.65           0.0         0.0      

             Underwood          31            3.00          2.36          32.3         0.0      

             Wilton             34            1.68          0.60           0.0         0.0      

Mercer                         279            1.68          1.07           3.9         0.0      

             Beulah             56            1.69          0.81           0.0         0.0      

             Golden Valley      18            4.29          0.85          55.6         0.0      

             Hazen             153            1.20          0.65           0.0         0.0      

             Stanton            28            2.40          0.91           3.6         0.0      

             Zap                24            1.89          0.59           0.0         0.0      

Morton                         320            1.57          1.60           5.0         0.0      

             Almont             11            2.34          1.14          18.2         0.0      

             Flasher            25            0.45          0.26           0.0         0.0      

             Glen Ullin         41            0.97          0.48           0.0         0.0      

             Hebron             25            3.53          3.68          24.0         0.0      

             Mandan            180            1.53          1.20           3.9         0.0      

             New Salem          38            1.62          1.17           2.6         0.0      

Mountrail                      172            1.19          1.06           2.3         0.0      

             New Town           62            0.58          0.53           0.0         0.0      

             Parshall           39            1.76          0.76           2.6         0.0      

             Plaza              22            1.70          1.71          13.6         0.0      

             Stanley            49            1.27          1.00           0.0         0.0      

Nelson                          67            1.84          1.50           6.0         0.0      

             Aneta              19            3.65          1.48          21.1         0.0      

             Petersburg         19            0.56          0.56           0.0         0.0      

             Tolna              29            1.49          0.47           0.0         0.0      

Oliver                          43            1.66          1.15           4.7         0.0      

             Center             43            1.66          1.15           4.7         0.0      

Pembina                        128            2.19          2.81          17.2         0.0      

             Cavalier           51            1.90          2.54           5.9         0.0      

             Drayton            56            0.84          0.45           0.0         0.0      

             St. Thomas         21            6.47          2.92          90.5         0.0      

Pierce                          63            1.46          0.94           0.0         0.0      

             Rugby              63            1.46          0.94           0.0         0.0      

Ramsey                         169            1.85          1.54          11.8         0.0      

             Crary               9            2.73          1.08          22.2         0.0      

             Devils Lake       117            1.11          0.68           0.0         0.0      

             Edmore             21            3.13          1.73          28.6         0.0      

             Starkweather       22            4.17          1.52          54.5         0.0      

Ransom                         103            5.05          4.21          49.5         1.0      

             Enderlin           17            1.99          2.40          11.8         0.0      

             Lisbon             78            6.18          4.09          62.8         1.3      

             Sheldon             8            0.49          0.35           0.0         0.0      

Renville                        99            1.13          0.81           0.0         0.0      

             Glenburn           40            1.18          0.55           0.0         0.0      

             Mohall             44            0.59          0.37           0.0         0.0      

             Sherwood           24            2.06          0.82           0.0         0.0      

Richland                       160            1.35          1.97           6.9         0.0      

             Lidgerwood          6            2.70          0.94          16.7         0.0      

             Wahpeton          115            1.65          2.18           8.7         0.0      

             Wyndmere           39            0.25          0.12           0.0         0.0      

Rolette                        136            1.10          1.10           3.7         0.0      

             Belcourt          103            0.87          0.77           1.0         0.0      

             Mylo                3            3.70          0.78          66.7         0.0      

             Rolette            30            1.63          1.49           6.7         0.0      

Sargent                         98            2.87          3.16          27.6         0.0      

             Forman             42            1.52          0.92           2.4         0.0      

             Gwinner            29            7.04          2.68          89.7         0.0      

             Milnor             27            0.50          0.22           0.0         0.0      

Sioux                           50            1.80          0.94           2.0         0.0      

             Fort Yates         33            1.54          0.86           0.0         0.0      

             Solen              17            2.31          0.87           5.9         0.0      

Stark                          389            4.50          6.19          21.6         4.6      

             Belfield           33           14.49         13.02          60.6        45.5      

             Dickinson         310            3.11          3.69          11.9         1.0      

             Richardton         27            9.23          4.32          85.2         0.0      

             Taylor             19            3.07          0.90          21.1         0.0      

Steele                          28            0.91          0.79           0.0         0.0      

             Finley             28            0.91          0.79           0.0         0.0      

Stutsman                       283            1.96          1.98          10.6         0.0      

             Jamestown         188            1.93          2.31          14.4         0.0      

             Kensal             20            2.81          1.35          10.0         0.0      

             Medina             27            1.61          0.37           0.0         0.0      

             Pingree            28            2.28          0.87           0.0         0.0      

             Spiritwood          5            0.70          0.61           0.0         0.0      

             Streeter           15            1.58          0.88           6.7         0.0      

Towner                          97            1.00          0.72           0.0         0.0      

             Bisbee             21            0.94          0.50           0.0         0.0      

             Cando              47            0.86          0.68           0.0         0.0      

             Rock Lake          29            1.29          0.84           0.0         0.0      

Traill                         162            2.06          3.50           6.8         1.2      

             Buxton             28            1.40          0.63           0.0         0.0      

             Hatton             20            2.90          1.63          25.0         0.0      

             Hillsboro          48            2.67          5.97           6.3         4.2      

             Mayville           66            1.64          1.53           4.5         0.0      

Walsh                          205            2.99          5.81          19.0         2.0      

             Adams              23            1.74          0.84           4.3         0.0      

             Edinburg           22            1.39          1.11           9.1         0.0      

             Fordville          13           16.35         16.84          84.6        30.8      

             Grafton           105            2.02           2.31         17.1         0.0      

             Lankin              5            1.64          0.42           0.0         0.0      

             Minto              28            3.14          1.86          25.0         0.0      

             Nash                2            3.15          0.05           0.0         0.0      

             Park River          7            2.21          0.75           0.0         0.0      

Ward                           845            1.27          1.17           2.8         0.0      

             Berthold           24            0.26          0.09           0.0         0.0      

             Des Lacs           59            1.73          1.13           1.7         0.0      

             Kenmare            47            1.08          0.92           2.1         0.0      

             Makoti             13            2.85          0.79          15.4         0.0      

             Minot             611            1.22          1.16           3.1         0.0      

             Sawyer             25            1.80          1.98           4.0         0.0      

             Surrey             57            1.24          0.60           0.0         0.0      

Wells                           55            1.05          1.02           0.0         0.0      

             Bowdon             13            0.89          0.73           0.0         0.0      

             Fessenden          25            0.36          0.21           0.0         0.0      

             Hurdsfield          7            2.63          0.83           0.0         0.0      

             Sykeston           10            1.89          0.84           0.0         0.0      

Williams                       235            1.76          1.68           4.3         0.0      

             Tioga              60            1.52          0.81           0.0         0.0      

             Williston        175             1.84           1.89           5.7         0.0      



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