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Radon Day Care Survey in North Dakota 1991-1992 During the second and third years of a three year grant from the EPA, the Department began testing for radon in over 2,000 licensed day care facilities. All day cares in the State were invited to participate in the survey. The day care facilities are licensed by the North Dakota Department of Human Services. During January 1991, the Department mailed 2,019 application packets to day care operators. Of the 2,019 day care facilities solicited, 545 facilities responded over the two-year period. Radon reports were not received from any day care facilities in seven counties. Tables 7 and 8 represent the city and county statistics derived from the day care radon survey. Sampling The Department followed EPA guidance for sampling protocol. This resulted in a significant number of parameters as shown in Table 7. Every third facility was sent a duplicate and every seventh facility received a field blank.
The Department followed EPA guidance to formulate its quality assurance plan and used the National Database format for recording collected data. The precision was determined by locating two samplers next to each other. Precision 1991 - Coefficient of variation 16.7% / Standard deviation 29.6. Precision 1992 - Coefficient of variation 9.5% / Standard deviation 11.4. The coefficient of variation is defined as the product of 100 and the standard deviation divided by the average of the two duplicate samples. Based on these tests, the day care radon measurements appear to be relatively precise. The accuracy was determined from a series of samples that were exposed in radon chambers in laboratories at the Office of Radiation Programs - National Air and Radiation Environmental Laboratory, Las Vegas, Nevada (1991) facility or Montgomery, Alabama (1992) facility. A total of 24 sampling vials were sent to Las Vegas and 181 sampling vials to Montgomery. A summary of the accuracy tests is given below: DAY CARE ACCURACY STATISTICS BY PARAMETER KNOWN % OF KNOWN STANDARD
YEAR pCi/l CONCENTRATION DEVIATION
1991 5.9 72.7 4.73
1991 11.9 93.5 13.44
1992 5.4 110.7 12.37
1992 12.8 110.5 4.86
The day care radon measurements are accurate except for the 5.9 pCi/l concentration (72.7%) in 1991. The high standard deviations (13.44 and 12.37) are indicative of large variations which are a concern to the Department. PARAMETERS - Description of Statistics by Selected Parameter The results of the parameters measured for day care facilities are found in Table 7. Mobile Home Type of Building Type of Basement Test Location Floor SUMMARY Most homes were closed, not using their fireplace, did not have an air conditioner on and did not have a central air conditioning system. The database contained 1,686 samples with an arithmetic mean concentration of 5.26 pCi/l. The standard deviation was 6.89. The percentages of samples greater than 4 or 20 pCi/l were 41.4% and 3.0%, respectively. FIGURE 3 - Log Normal Distribution
Number of Samples: 1686 The curve obtained from the Day Care Survey is LOGNORMAL (see Figure 3). The above graph is combined with the lognormal graphs for the other surveys and may be found in Figure 8. TABLE 7 DAY CARE SURVEY STATISTICS SUMMARY PERCENTAGE
OF
NUMBER ARITHMETIC SAMPLE
OF ARITHMETIC STANDARD GREATER THAN
PARAMETERS SAMPLES MEAN DEVIATION 4 pCi/l 20 pCi/l
MOBILE HOME
Yes 47 3.8 5.0 19.1 2.1
No 1639 5.3 6.9 42.0 3.0
TYPE OF BUILDING
Single Family 1434 5.6 7.3 45.3 3.1
Multi Family 82 3.0 1.7 23.2 0.0
Business 56 3.8 5.7 19.6 7.1
School 41 3.0 4.4 17.1 2.4
Other 73 2.5 1.9 16.4 0.0
BASEMENT CRAWL SPACE
SLAB-ON-GRADE
Basement 1311 5.5 6.7 45.2 3.1
Crawl Space 62 4.7 7.4 22.6 8.1
Slab-on-Grade 194 4.7 9.3 29.9 2.1
Other 119 3.4 3.4 28.6 0.8
TEST LOCATION FLOOR
Basement 531 6.9 8.1 57.1 4.5
First Floor 1039 4.6 6.4 35.4 2.4
Second Floor & Above 116 3.4 3.3 23.3 0.9
HEAT DISTRIBUTION TYPE
Hot Air 1216 5.4 6.8 43.4 3.2
Hot Water 239 3.6 4.1 28.0 1.3
Radiant 71 4.2 3.3 42.3 0.0
Individual Room Units 116 7.6 11.8 48.3 6.0
Other 42 4.8 5.7 35.7 2.4
ROOM TYPE
Bedroom 504 5.1 6.6 41.5 2.0
Family Room 213 5.6 6.2 46.5 1.9
Living Room 352 4.6 7.2 35.2 1.7
Unfinished Basement 58 6.9 6.2 63.8 6.9
Office 4 5.7 4.5 50.0 0.0
Classroom 84 3.3 4.1 19.0 2.4
Other 196 5.3 7.0 39.3 4.1
Finished Basement 25 7.1 4.7 68.0 0.0
Kitchen 51 5.4 8.8 33.3 3.9
Recreation Room 42 7.0 6.4 66.7 7.1
Dining Room 42 5.3 7.6 33.3 4.8
Play Room 66 7.0 7.6 54.5 6.1
TV Room 6 4.8 3.3 50.0 0.0
Sleeping Room 29 6.4 48.3 13.8
Nursery 13 8.0 7.3 30.8 7.7
15.2
GEOLOGICAL REGION
1 191 5.2 8.3 33.5 3.7
2 606 7.0 8.9 54.3 5.1
3 889 4.1 4.3 34.3 1.3
BASEMENT SUMP
Yes 440 7.5 9.4 54.3 7.0
No 1246 4.5 5.6 36.8 1.5
TYPE OF FACILITY
Center 89 3.8 5.3 19.1 5.6
Family 1084 5.0 5.5 42.1 2.6
Group 477 6.4 9.6 44.7 3.6
Half-day 11 3.7 2.3 45.5 0.0
Multiple License 17 3.4 2.8 35.3 0.0
Public Approval 6 1.1 0.8 0.0 0.0
CLOSED HOUSE
Yes 1146 5.3 7.0 41.1 3.1
No 540 5.2 6.7 42.0 2.8
FIREPLACE IN USE
Yes 71 4.9 5.2 45.1 1.4
No 1615 5.3 7.0 41.2 3.0
AIR CONDITIONER IN USE
Yes 9 10.2 8.8 44.4 11.1
No 1677 5.2 6.9 41.4 2.9
CENTRAL AIR SYSTEM
Yes 648 6.4 8.7 48.0 4.9
No 1038 4.5 5.4 37.3 1.7
TABLE8 DAY CARE 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 6 13.3 7.4 83.3 16.7
Barnes 33 8.8 7.9 75.8 15.2
Bottineau 12 3.4 1.8 41.7 0.0
Bowman 13 22.7 22.4 76.9 38.5
Burke 7 2.3 0.2 0.0 0.0
Burleigh 422 3.7 3.6 29.1 0.9
Cass 213 7.6 9.9 62.9 4.7
Cavalier 24 3.8 2.4 45.8 0.0
Dickey 5 4.3 2.4 60.0 0.0
Divide 8 3.8 0.6 25.0 0.0
Dunn 8 2.1 0.7 0.0 0.0
Eddy 4 3.0 1.8 50.0 0.0
Emmons 19 3.6 1.9 31.6 0.0
Golden Valley 8 1.8 1.9 12.5 0.0
Grand 139 11.4 11.0 85.6 10.1
Forks
Grant 2 9.1 0.8 100.0 0.0
Griggs 27 3.3 2.0 37.0 0.0
Hettinger 9 2.5 1.9 22.2 0.0
Kidder 5 3.0 0.9 20.0 0.0
Lamoure 9 4.1 3.4 44.4 0.0
Logan 14 2.6 0.9 7.1 0.0
McHenry 14 4.9 5.8 35.7 7.1
McIntosh 20 6.2 2.7 80.0 0.0
McKenzie 10 2.8 0.7 0.0 0.0
McLean 24 3.6 3.8 16.7 0.0
Mercer 8 3.5 1.4 25.0 0.0
Morton 80 3.7 3.2 28.8 1.3
Mountrail 24 4.9 5.9 29.2 4.2
Nelson 1 3.2 0.0 0.0 0.0
Pembina 16 4.2 4.1 25.0 0.0
Pierce 10 2.5 2.6 10.0 0.0
Ramsey 8 3.8 2.2 37.5 0.0
Ransom 14 11.0 6.4 78.6 7.1
Renville 9 3.1 1.4 33.3 0.0
Richland 53 1.8 1.4 9.4 0.0
Rolette 20 2.4 1.4 5.0 0.0
Sargent 5 7.5 9.2 40.0 20.0
Stark 65 3.4 2.6 27.7 0.0
Steele 3 6.9 3.4 100.0 0.0
Stutsman 136 4.2 2.5 49.3 0.0
Towner 3 6.1 1.2 100.0 0.0
Traill 29 6.5 3.5 51.7 0.0
Walsh 19 14.7 13.1 68.4 31.6
Ward 68 3.2 2.9 22.1 0.0
Wells 14 2.8 1.7 35.7 0.0
Williams 46 2.4 2.3 13.0 0.0
TABLE 9 DAY CARE 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 6 13.30 7.42 83.3 16.7
Hettinger 6 13.30 7.42 83.3 16.7
Barnes 33 8.80 7.90 100.0 0.0
Litchville 4 6.33 0.65 100.0 0.0
Valley City 29 9.14 8.37 72.4 17.2
Bottineau 12 3.35 1.81 41.7 0.0
Bottineau 12 3.35 1.81 41.7 0.0
Bowman 13 22.74 22.37 76.9 38.5
Bowman 10 27.15 23.80 70.0 50.0
Scranton 3 8.03 0.26 100.0 0.0
Burke 7 2.27 0.24 0.0 0.0
Bowbells 5 2.28 0.28 0.0 0.0
Lignite 2 2.25 0.05 0.0 0.0
Burleigh 422 3.72 3.64 29.1 0.9
Baldwin 3 2.37 0.19 0.0 0.0
Bismarck 385 3.77 3.68 29.9 1.0
Lincoln 26 2.13 1.31 11.5 0.0
Menoken 3 6.43 0.56 100.0 0.0
Bismarck 1 2.70 0.00 0.0 0.0
Wing 4 8.40 5.97 50.0 0.0
Cass 213 7.58 9.89 62.9 4.7
Casselton 5 9.70 3.01 100.0 0.0
Fargo 134 7.72 8.65 64.9 5.2
Harwood 11 5.78 5.80 63.6 9.1
Kindred 5 5.22 0.27 100.0 0.0
Mapleton 3 1.53 0.54 0.0 0.0
West Fargo 53 8.04 13.84 52.8 3.8
Wheatland 2 5.60 1.40 100.0 0.0
Cavalier 24 3.80 2.37 45.8 0.0
Langdon 24 3.80 2.37 45.8 0.0
Dickey 5 4.32 2.37 60.0 0.0
Ellendale 5 4.32 2.37 60.0 0.0
Divide 8 3.84 0.64 25.0 0.0
Crosby 8 3.84 0.64 25.0 0.0
Dunn 8 2.13 0.73 0.0 0.0
Killdeer 8 2.13 0.73 0.0 0.0
Eddy 4 3.03 1.78 50.0 0.0
New Rockford 4 3.03 1.78 50.0 0.0
Emmons 19 3.55 1.95 31.6 0.0
Hazelton 4 1.85 1.48 25.0 0.0
Linton 15 4.01 1.80 33.3 0.0
Golden 8 1.75 1.89 12.5 0.0
Valley
Beach 8 1.75 1.89 12.5 0.0
Grand 139 11.38 10.97 85.6 10.1
Forks
Emerado 3 7.73 6.58 66.7 0.0
Grand Forks 132 11.63 11.15 86.4 10.6
Larimore 1 0.90 0.00 0.0 0.0
Thompson 3 7.43 0.25 100.0 0.0
Grant 2 9.05 0.75 100.0 0.0
Elgin 2 9.05 0.75 100.0 0.0
Griggs 27 3.31 2.02 37.0 0.0
Cooperstown 23 2.70 1.38 26.1 0.0
Hannaford 4 6.78 1.55 100.0 0.0
Hettinger 9 2.54 1.92 22.2 0.0
Mott 3 4.83 1.09 66.7 0.0
New England 3 1.70 1.24 0.0 0.0
Regent 3 1.10 0.57 0.0 0.0
Kidder 5 3.02 0.92 20.0 0.0
Steele 5 3.02 0.92 20.0 0.0
Lamoure 9 4.07 3.36 44.4 0.0
Edgeley 5 1.08 0.19 0.0 0.0
Lamoure 4 7.80 0.47 100.0 0.0
Logan 14 2.64 0.93 7.1 0.0
Gackle 5 2.52 0.37 0.0 0.0
Napoleon 9 2.70 1.12 11.1 0.0
McHenry 14 4.94 5.77 35.7 7.1
Towner 6 7.83 7.82 50.0 16.7
Upham 4 2.50 0.07 0.0 0.0
Velva 4 3.03 1.56 50.0 0.0
McIntosh 20 6.16 2.72 80.0 0.0
Ashley 4 6.80 0.57 100.0 0.0
Wishek 16 5.99 3.01 75.0 0.0
McKenzie 10 2.79 0.72 0.0 0.0
Watford City 10 2.79 0.72 0.0 0.0
McLean 24 3.60 3.75 16.7 0.0
Garrison 7 1.60 1.06 0.0 0.0
Max 3 0.90 0.00 0.0 0.0
Turtle Lake 8 7.15 4.60 50.0 0.0
Washburn 6 2.55 0.73 0.0 0.0
Mercer 8 3.45 1.38 25.0 0.0
Beulah 5 4.26 1.14 40.0 0.0
Stanton 3 2.10 0.14 0.0 0.0
Morton 80 3.70 3.17 28.8 1.3
Hebron 2 4.95 1.05 50.0 0.0
Mandan 74 3.67 3.29 29.7 1.4
New Salem 4 3.58 0.13 0.0 0.0
Mountrail 24 4.90 5.95 29.2 4.2
New Town 5 3.44 0.46 20.0 0.0
Parshall 4 1.95 1.57 25.0 0.0
Plaza 3 19.73 2.95 100.0 33.3
Stanley 12 2.79 2.12 16.7 0.0
Nelson 1 3.20 0.00 0.0 0.0
Lakota 1 3.20 0.00 0.0 0.0
Pembina 16 4.23 4.11 25.0 0.0
Cavalier 12 4.76 4.63 33.3 0.0
St. Thomas 4 2.65 0.32 0.0 0.0
Pierce 10 2.45 2.57 10.0 0.0
Rugby 7 1.97 0.22 0.0 0.0
Wolford 3 3.57 4.48 33.3 0.0
Ramsey 8 3.80 2.17 37.5 0.0
Devils Lake 5 4.26 2.54 40.0 0.0
Starkweather 3 3.03 0.93 33.3 0.0
Ransom 14 10.99 6.37 78.6 7.1
Enderlin 3 1.80 0.80 0.0 0.0
Lisbon 11 13.49 4.71 100.0 9.1
Renville 9 3.14 1.41 33.3 0.0
Glenburn 9 3.14 1.41 33.3 0.0
Richland 53 1.83 1.40 9.4 0.0
Barney 1 0.10 0.00 0.0 0.0
Colfax 6 0.98 0.38 0.0 0.0
Hankinson 4 0.80 0.07 0.0 0.0
Wahpeton 38 1.99 1.46 10.5 0.0
Wyndmere 4 3.05 0.82 25.0 0.0
Rolette 20 2.40 1.44 5.0 0.0
Dunseith 5 3.50 1.70 20.0 0.0
Rolette 9 2.32 0.53 0.0 0.0
Rolla 2 3.80 0.00 0.0 0.0
St. John 4 0.50 0.07 0.0 0.0
Sargent 5 7.50 9.22 40.0 20.0
Forman 1 25.50 0.0 100.0 100.0
Milnor 4 3.00 2.23 25.0 0.0
Stark 65 3.41 2.61 27.7 0.0
Belfield 3 4.17 0.26 66.7 0.0
Dickinson 57 3.32 2.65 22.8 0.0
South Heart 5 3.98 2.77 60.0 0.0
Steele 3 6.87 3.43 100.0 0.0
Hope 3 6.87 3.43 100.0 0.0
Stutsman 136 4.18 2.48 49.3 0.0
Jamestown 129 3.97 2.33 46.5 0.0
Montpelier 4 8.43 2.11 100.0 0.0
Streeter 3 7.70 0.94 100.0 0.0
Towner 3 6.13 1.25 100.0 0.0
Cando 3 6.13 1.25 100.0 0.0
Traill 29 6.46 3.47 51.7 0.0
Buxton 3 2.70 0.22 0.0 0.0
Hatton 5 8.58 3.91 80.0 0.0
Hillsboro 6 4.02 0.91 16.7 0.0
Mayville 6 8.57 3.84 66.7 0.0
Portland 9 6.77 2.37 66.7 0.0
Walsh 19 14.66 13.15 68.4 31.6
Grafton 19 14.66 13.15 68.4 31.6
Ward 68 3.24 2.88 22.1 0.0
Berthold 1 2.90 0.00 0.0 0.0
Minot 67 3.25 2.90 22.4 0.0
Wells 14 2.79 1.73 35.7 0.0
Harvey 14 2.79 1.73 35.7 0.0
Williams 46 2.42 2.32 13.0 0.0
Alamo 4 4.23 1.15 50.0 0.0
Ray 5 1.62 1.70 20.0 0.0
Wildrose 3 7.67 5.35 66.7 0.0
Williston 34 1.86 0.97 2.9 0.0
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