Radon and Its Decay Products - ACS Publications - American

Chapter 4

Downloaded by COLUMBIA UNIV on January 21, 2018 | http://pubs.acs.org Publication Date: February 5, 1987 | doi: 10.1021/bk-1987-0331.ch004

Measurements of R a d o n Concentrations i n Residential Buildings i n the Eastern United States Andreas C. George and Lawrence E. Hinchliffe Environmental Measurements Laboratory, U.S. Department of Energy, New York, NY 10014 As part of a program to develop and test radon survey techniques, passive activated carbon samplers were used to measure radon concentrations in 380 buildings in six states in the eastern United States. Measurements were made in the basement and living areas of each residential building, and in some work locations of several plant buildings during summer and winter. The activated carbon samplers performed well in these tests, and the logistics via U. S. mail were satis factory. The lowest concentrations of radon were found in: Long Island, NY, Luzerne County, PA, and South Carolina. The remainder of the test areas showed a substantial number of buildings to have radon levels above the Environmental Protection Agency's and the National Council on Radiation Protection and Measure ments's guideline action levels. The arithmetic mean concentrations of radon in the living areas in the different regions ranged from 1.1 pCi/1 to 9.3 pCi/1 (0.0055 to 0.0465 WL) during the winter months. The dose equivalent rate to the bronchial epithelial cells of the occupants of these buildings ranged from 1.4 to 10.7 rem/yr. Although only one area lies on the Reading Prong, which extends through New Jersey, several of the regions can be considered hot areas or anomalous regions with similar problems as the Prong. The estimated risk from the observed radon distribu tions is such that a substantial fraction of the northeastern United States population is exposed to levels high enough to warrant immediate attention. In recent years, there has been growing concern about homes with high indoor radon concentration levels and a potential for increased risk of lung cancer among occupants of these buildings. Residential buildings measured in the past two years, frequently had radon concentrations 1 to 2 orders of magnitude greater than average. These high concentration levels suggest that it is necessary to This chapter not subject to U.S. copyright. Published 1987, American Chemical Society

Hopke; Radon and Its Decay Products ACS Symposium Series; American Chemical Society: Washington, DC, 1987.


4.

GEORGE AND HINCHLIFFE

Concentrations in Residential Buildings

43

o b t a i n exposure d a t a from a wide v a r i e t y o f b u i l d i n g s and geographi c a l l o c a t i o n s throughout the U n i t e d S t a t e s i n o r d e r t o b e t t e r d e f i n e and u n d e r s t a n d the r a d i a t i o n exposure o f the g e n e r a l p o p u l a t i o n t o i n d o o r radon and radon progeny. The f i r s t comprehensive measurements i n the U n i t e d S t a t e s o f i n d o o r radon and radon progeny and p a r t i c l e s i z e d i s t r i b u t i o n s were made by the E n v i r o n m e n t a l Measurements L a b o r a t o r y (EML) i n the l a t e 1970's a t p l a c e s a s s o c i a t e d w i t h the s i t e s d e c l a r e d excess by Atomic Energy Commission. Because o f the c o n c e r n e x p r e s s e d by l o c a l government o f f i c i a l s and p r i v a t e c i t i z e n s about p o s s i b l e e l e v a t e d radon l e v e l s i n nearby r e s i d e n c e s due t o t r a n s p o r t and i n f i l t r a t i o n of radon from contaminated s i t e s , the Department o f Energy (DOE) sponsored s t u d i e s t o determine the c o n c e n t r a t i o n l e v e l s i n uneontaminated homes s i t u a t e d near these s i t e s . The measurements were made i n b u i l d i n g s i n s e l e c t e d l o c a t i o n s c o n s i d e r e d background a r e a s i n the New York C i t y m e t r o p o l i t a n a r e a (George and B r e s l i n , 1980) and a t s u s p e c t h i g h l e v e l a r e a s i n the v i c i n i t y o f the M i d d l e s e x Sampling P l a n t i n M i d d l e s e x , NJ, a t the Lake O n t a r i o O r d i n a n c e Works F a c i l i t y i n L e w i s t o n , NY, and a t the Canonsburg I n d u s t r i a l P a r k i n Canonsburg, PA (George and Eng, 1981). Annual mean c o n c e n t r a t i o n s o f radon o r radon progeny were e s t i m a t e d i n each b u i l d i n g by 1 o r 2 week-long measurements r e p e a t e d s e v e r a l times o v e r a p e r i o d o f 2 y r (1976-1978 o r 1978-1980). P a s s i v e i n t e g r a t i n g radon m o n i t o r s (George and B r e s l i n , 1977) and a c t i v e i n t e g r a t i n g working l e v e l m o n i t o r s (Guggenheim e t a l . , 1979) d e v e l o p e d by EML were used throughout the m o n i t o r i n g p e r i o d . As the demand f o r radon measurements i n c r e a s e d , the need f o r s i m p l e r and l e s s c o s t l y m o n i t o r i n g d e v i c e s grew p r o p o r t i o n a t e l y , r e q u i r i n g the development o f i n s t r u m e n t s and methods a p p l i c a b l e t o b r o a d e r f i e l d s t u d i e s . Measurements o f radon progeny, which a r e the more d i f f i c u l t t o make, can be r e p l a c e d w i t h measurements o f radon t o p r o v i d e i n f o r m a t i o n on the upper l i m i t f o r the p o t e n t i a l a l p h a energy exposure from radon progeny. T h e r e f o r e , s i m p l e p a s s i v e radon m o n i t o r s f o r i n t e g r a t e d measurements o f 1 t o 12 months ( A l t e r and F l e i s c h e r , 1981) o r as l i t t l e as 3 t o 4 days (George, 1984) a r e d e v e l o p e d . From p r e v i o u s s t u d i e s we found t h a t a s i n g l e measurement o f the average c o n c e n t r a t i o n o f radon o v e r p e r i o d s o f days, r e p e a t e d i n d i f f e r e n t seasons, i s adequate t o a s s e s s the exposure and r a d i a t i o n dose o f the o c c u p a n t s o f b u i l d i n g s (George and B r e s l i n , 1980; George, 1984). T h i s approach was u n d e r t a k e n by EML and o t h e r s t o d e v e l o p and s u c c e s s f u l l y t e s t p a s s i v e a c t i v a t e d c a r b o n m o n i t o r s (George, 1984; Cohen and Cohen, 1983) s u i t a b l e f o r i n t e g r a t e d measurements o f e n v i r o n m e n t a l l e v e l s o f radon o v e r a p e r i o d o f a few days (3 t o 7 d a y s ) . The advantages o f t h i s new d e v i c e a r e t h a t i t i s s i m p l e , r e u s a b l e , m a i n t e n a n c e - f r e e , c o m p l e t e l y p a s s i v e , no t r a n s f e r o f sample i s r e q u i r e d , and i t i s a l s o r e a d i l y h a n d l e d i n the m a i l . The f i r s t use o f t h i s t e c h n o l o g y was t o make measurements of radon i n s e l e c t e d homes n e a r P h i l a d e l p h i a , P e n n s y l v a n i a and i n homes n e a r Damascus, MD (George e t a l . , 1984). I n t h i s s u r v e y o f 72 r e s i d e n t i a l b u i l d i n g s , i n the two l o c a l i t i e s , homes w i t h h i g h c o n c e n t r a t i o n s o f radon were i d e n t i f i e d . At about the same t i m e , from newspaper a r t i c l e s p u b l i s h e d i n c e r t a i n a r e a s i n the n o r t h e a s t e r n U n i t e d S t a t e s , radon was b e g i n n i n g t o be c o n s i d e r e d a p o s s i b l e i n d o o r a i r p o l l u t a n t and home owners were a l e r t e d t o the


RADON AND ITS DECAY PRODUCTS

44

p o s s i b l e h e a l t h e f f e c t s from radon exposure i n c e r t a i n s i t u a t i o n s . As p a r t o f the radon program a t EML t o d e v e l o p o r improve and f i e l d t e s t radon m o n i t o r s , a m o d i f i e d a c t i v a t e d carbon d e v i c e (Warner, 1986) was developed t o o b t a i n h i g h e r measurement sensitivity. As a r e s u l t , we have surveyed 380 b u i l d i n g s i n s i x s t a t e s i n the e a s t e r n u n i t e d S t a t e s . The purpose o f the measurements r e p o r t e d i n t h i s paper was t o t e s t the f e a s i b i l i t y o f the new v e r s i o n o f the p a s s i v e a c t i v a t e d carbon d e v i c e and t o o b t a i n data on i n d o o r radon l e v e l s i n d i f f e r e n t g e o g r a p h i c a l l o c a t i o n s .


Location of Buildings The 380 b u i l d i n g s s u r v e y e d were l o c a t e d i n s i x s t a t e s (shown i n F i g u r e 1) and c o n s i s t e d p r i m a r i l y o f s i n g l e f a m i l y r e s i d e n c e s w i t h the e x c e p t i o n o f s e v e r a l p l a n t b u i l d i n g s o p e r a t e d b y E . I . Dupont f o r the U. S. Department o f E n e r g y . The p l a n t l o c a t i o n s were surveyed w i t h the c o o p e r a t i o n o f the H e a l t h P h y s i c s Group a t the Savannah R i v e r P l a n t i n A i k e n , South C a r o l i n a who a l s o arranged f o r the radon measurements t o be taken i n 41 r e s i d e n t i a l b u i l d i n g s i n 15 towns w i t h i n a r a d i u s o f 40 km from the p l a n t . I n t h e Washington, D.C. a r e a , i n c o o p e r a t i o n w i t h t e l e v i s i o n s t a t i o n WJLA-TV, we measured 52 r e s i d e n t i a l b u i l d i n g s , which were l o c a t e d i n 9 towns i n n o r t h e r n V i r g i n i a and i n 22 towns i n M a r y l a n d . Three r e s i d e n t i a l b u i l d i n g s i n Washington, D.C. were a l s o i n c l u d e d . Through the c o o p e r a t i o n o f WNEP-TV16, s e r v i n g the W i l k e s - B a r r e / S c r a n t o n area i n P e n n s y l v a n i a , measurements f o r radon c o n c e n t r a t i o n l e v e l s were made i n 42 r e s i d e n t i a l b u i l d i n g s i n 34 towns i n n o r t h e r n Pennsylvania. I n an a l t e r n a t e s i t e i n L u z e r n e County P e n n s y l v a n i a , we measured radon c o n c e n t r a t i o n s i n 41 r e s i d e n t i a l b u i l d i n g s i n 22 towns. T h i s r e q u e s t came from the Commission on Economic Opport u n i t y , a non p r o f i t s o c i a l s e r v i c e agency t h a t w i n t e r i z e d t h e homes o f low income f a m i l i e s . We surveyed 20 homes f o r radon i n 14 towns i n New J e r s e y w i t h i n a r a d i u s o f 25 km from C h e s t e r , New J e r s e y i n c o o p e r a t i o n w i t h B e l l Communication R e s e a r c h , I n c . I n a second g e o g r a p h i c a l r e g i o n encompassing 5 c o u n t i e s c e n t e r e d around M o r r i s County, we measured radon c o n c e n t r a t i o n s i n 50 r e s i d e n t i a l b u i l d i n g s s c a t t e r e d i n 24 towns through the c o o p e r a t i o n o f a l o c a l i n s u r a n c e company. In New York S t a t e , we surveyed t h r e e g e o g r a p h i c a l r e g i o n s , one i n Long I s l a n d , one i n the A l b a n y r e g i o n and the t h i r d i n the Syracuse a r e a . I n Long I s l a n d we measured radon c o n c e n t r a t i o n l e v e l s i n 38 r e s i d e n t i a l b u i l d i n g s i n 23 towns i n c o n j u n c t i o n w i t h measurements o f i n d o o r gamma r a d i a t i o n e x p o s u r e s . I n the A l b a n y area through the c o o p e r a t i o n o f the New Y o r k S t a t e Energy R e s e a r c h and Development A u t h o r i t y (ERDA), we measured radon c o n c e n t r a t i o n i n 29 b u i l d i n g s i n 16 towns w i t h i n a r a d i u s o f 20 km from A l b a n y . The t h i r d r e g i o n , i n t h e v i c i n i t y o f S y r a c u s e , was surveyed f o r radon through a r e q u e s t from an e n g i n e e r i n g company s p e c i a l i z i n g i n b u i l d i n g energy c o n s e r v a t i o n . We measured 26 b u i l d i n g s i n 6 towns c e n t e r e d around S y r a c u s e . From a q u e s t i o n n a i r e t h a t the occupants o f t h e b u i l d i n g s r e t u r n e d t o us a l o n g w i t h the exposed d e t e c t o r s , we were a b l e t o determine b u i l d i n g c h a r a c t e r i s t i c s . Most o f t h e b u i l d i n g s were s i n g l e - f a m i l y r e s i d e n c e s w i t h f u l l basements. S u p r i s i n g l y , many



F i g u r e 1.

Geographical d i s t r i b u t i o n

of r e s i d e n c e s i n s i x s t a t e s .



46

basements mere f i n i s h e d and some p e o p l e spend a s u b s t a n t i a l p a r t o f t h e i r time t h e r e . The b u i l d i n g s were o f wood-frame o r b r i c k c o n s t r u c t i o n w i t h h e a t i n g systems o f a l l t y p e s . Domestic water s u p p l i e s were m o s t l y from p u b l i c s o u r c e s , b u t a s u b s t a n t i a l number of homes used w e l l water l o c a t e d on s i t e . The b u i l d i n g s ranged i n age from 100 y r o l d . Newer homes seemed t o be b u i l t w i t h energy c o n s e r v i n g measures i n mind, a l t h o u g h some owners o f o l d e r homes (>15 y e a r s o l d ) , i n d i c a t e d t h a t they added some form o f i n s u l a t i o n t o r e n d e r them a i r t i g h t f o r energy c o n s e r v a t i o n p u r p o s e s .


Monitoring Procedures The e s t i m a t i o n o f annual mean c o n c e n t r a t i o n o f radon was d e t e r m i n e d i n each b u i l d i n g by making measurements d u r i n g the w i n t e r ( h e a t i n g season) and d u r i n g the summer. The r e g i o n s we s u r v e y e d g e n e r a l l y have a s i x month p e r i o d i n which homes a r e m a i n t a i n e d a t maximum c l o s e d c o n d i t i o n s from O c t o b e r t o A p r i l . Summer weather c o n d i t i o n s g e n e r a l l y p r e v a i l from May t h r o u g h September. Measurements f o r radon were made t w i c e i n each b u i l d i n g d u r i n g the two s e a s o n s . One d e t e c t o r was u s u a l l y exposed i n a l o c a t i o n i n the home where occupants were l i k e l y t o spend most of t h e i r t i m e . We denoted t h a t l o c a t i o n as l i v i n g a r e a . A second d e t e c t o r was p l a c e d i n the basement i f t h e r e was one, because basements a r e more o f t e n the s o u r c e o f radon i n a b u i l d i n g . S i n c e l i v i n g h a b i t s change w i t h more f r e q u e n t use o f basements as p l a y r o o m s , machine shops o r even as bedrooms, we thought i t p r u d e n t t o measure the h i g h e s t p o t e n t i a l radon c o n c e n t r a t i o n l e v e l s t o which r e s i d e n t s o f b u i l d i n g s might be exposed. The d e t e c t o r used t o measure i n d o o r radon was the l a t e s t v e r s i o n o f the p a s s i v e a c t i v a t e d c a r b o n d e v i c e d e v e l o p e d a t EML (George, 1984; Warner, 1986), which c o n s i s t s o f a t h i n - w a l l e d aluminum c a n i s t e r w i t h a s c r e e n c o v e r t o expose 80 g o f c a r b o n t o the t e s t atmosphere. A l t h o u g h n o t as p h y s i c a l l y rugged as e a r l i e r models, p r o p e r l y packed t h i s m o n i t o r i n g d e v i c e was as s u c c e s s f u l i n c o n d u c t i n g the s u r v e y s t h r o u g h the m a i l . A f t e r the end o f the 4-day exposure, the d e t e c t o r s were r e t u r n e d t o EML f o r a n a l y s i s . The amount of radon adsorbed on the carbon d e v i c e was d e t e r m i n e d by c o u n t i n g the gamma r a y s of radon progeny i n e q u i l i b r i u m w i t h r a d o n . The c o n c e n t r a t i o n s o f radon i n the b u i l d i n g s were d e t e r m i n e d from the r a d i o a c t i v i t y i n the d e v i c e and t h e c a l i b r a t i o n f a c t o r , o b t a i n e d i n a radon chamber, t h a t takes i n t o c o n s i d e r a t i o n the l e n g t h o f exposure and a c o r r e c t i o n f o r the amount of w a t e r v a p o r adsorbed d u r i n g the e x p o s u r e . The lower l i m i t of d e t e c t i o n w i t h t h i s t e c h n i q u e i s 0.2 p C i / 1 f o r a measurement p e r i o d o f 4 days when the t e s t sample i s counted f o r 10 min, 4 days a f t e r the end o f exposure. More than 90% o f the radon m o n i t o r i n g d e v i c e s were a n a l y z e d s u c c e s s f u l l y . Most of the u n s u c c e s s f u l measurements were due t o d e l a y s o r l o s s e s caused by the p a r t i c i pants. R e s u l t s and D i s c u s s i o n The r e s u l t s o f a l l measurements a r e summarized i n T a b l e s I through IX, where we p r e s e n t the range o f v a l u e s and the a r i t h m e t i c means


4. GEORGE AND HINCHLIFFE

Concentrations in Residential Buildings

47


Table I . Radon Concentrations and R a d i a t i o n Dose Rate Equivalent to E p i t h e l i a l C e l l s o f the Occupants of R e s i d e n t i a l and Plant B u i l d i n g s In and Near the Savannah R i v e r P l a n t

% Equal to or Greater Than

Radon Concen. (pCi/1) Min.

Max.

Mean

GM

GSD

4 pCi/1 8 pCi/1

Winter

0.3

12

1.48

0.95 2.0

2

0

Summer

0.1

2.6

0.85

0.63 1.9

0

0

0.8

5.6

2.7

2.3

17

2

0.1

0.8

0.37

0.29 3.0

Dose Rate (rem/yr)

L i v i n g Area

(4.1)

Basement Winter

1.9

(9.6)

Plant B u i l d i n g s Summer

Note: Number o f b u i l d i n g s - 41 p r i v a t e residences

and 41 l o c a t i o n s i n the p l a n t .

American Chemical Society Library 1155 16th St., N.W.

Hopke; Radon and Its Decay Products D.C. Society: 20036Washington, DC, 1987. ACS Symposium Series;Washington, American Chemical


48


Table I I . Radon Concentrations and Radiation Dose Rate Equivalent to E p i t h e l i a l C e l l s of the Occupants of Residential Buildings i n Northern V i r g i n i a and Maryland

Radon Concen. (pCi/1)

% Equal to or G r e a t e r Than

Nin.

Max.

Mean

GM

GSD

4 pCi/1

8 pCi/1

Winter

0.3

28.4

4.3

2.1

3.6

31

15

Summer

0.3

718

1.8

1.2

2.3

7

Winter

0.5

59

7.6

4.2

3.6

51

30

Summer

0.6

21

4.9

3.2

2.8

39

18

Living

Dose Rate (rem/yr)

Area

(10.7) 0

Basement

(22.1)

Note: Number o f b u i l d i n g s = 41 p r i v a t e r e s i d e n c e s and 41 l o c a t i o n s i n the p l a n t . B u i l d i n g ages were from 2 t o 200 y e a r s . Percent of b u i l d i n g s

Radon and Its Decay Products - ACS Publications - American

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