OHice of Radiation Programs  ORP LV-78-6
            Env          Las Vegas Facility      May 1978
            Ay          P.O Box 15027
                       Las Vegas NV 89114

            Radiation
&EPA      Working Level
            Screening Survey
            of Structures Constructed
            of Materials Containing
            Pumice

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                                          Technical Note
                                             ORP/LV-78-6
         WORKING LEVEL SCREENING SURVEY

          OF STRUCTURES CONSTRUCTED OF

          MATERIALS CONTAINING PUMICE
               Richard L. Douglas
               Joseph M. Hans, Jr.
               Theodore A. Wolff*
OFFICE OF RADIATION PROGRAMS - LAS VEGAS FACILITY
      U.S. ENVIRONMENTAL PROTECTION AGENCY
            LAS VEGAS, NEVADA  89114
   NEW MEXICO HEALTH AND ENVIRONMENT DEPARTMENT
          RADIATION PROTECTION SECTION
               SANTA FE, NM  87501

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                           DISCLAIMER

     This report has been reviewed by the Office of Radiation
Programs-Environmental Analysis Division and Las Vegas Facility,
U.S. Environmental Protection Agency, and approved for publica-
tion.  Mention of trade names or commercial products does not
constitute an endorsement or recommendation for their use.
                                11

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                              PREFACE

     The Office of Radiation Programs of the U.S. Environmental
Protection Agency carries out a national program designed to
evaluate population exposure to ionizing and nonionizing radia-
tion, and to promote development of controls necessary to protect
the public health and safety.  This report describes a preliminary
evaluation of radon progeny levels and gamma radiation levels in
buildings constructed partially or entirely of block in which
pumice, having slightly elevated radioactivity levels, was used
as aggregate.  Readers of this report are encouraged to inform
the Office of Radiation Programs of any omissions or errors.
Comments or requests for further information are also invited.
                              Donald W. Hendricks
                              Director, Office of
                            Radiation Programs, LVF
                               111

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                         TABLE OF CONTENTS

                                                             Page

INTRODUCTION AND BACKGROUND                                     1

SURVEY METHODS                                                  2

RESULTS AND DISCUSSION                                          4

OTHER DATA                                                     12

COMPARISON OF RESULTS WITH STANDARDS                           17

CONCLUSIONS AND RECOMMENDATIONS                                18



                         LIST OF FIGURES


Number                                                       Page

  1.   Gross Indoor Working Level vs. Net Indoor Gamma
       Exposure Rate                                            9


                         LIST OF TABLES

Number                                                       Page
  1.   Individual Working Level Results for Structures
       in the Santa Fe - Espanola Area                          5

  2.   Summary of Working Level Results and Pertinent
       Parameters for Structures in the Santa Fe -
       Espanola Area                                            6

  3.   Radionuclide Content of Pumice and Block                 7A

  4.   Summary of Working Level Results and Pertinent
       Parameters for Structures in the Shiprock,
       New Mexico Area                                         13

  5.   Individual Working Level Results for Structures in
       Farmington                                              15

  6.   Summary of Working Level Results and Pertinent
       Parameters for Structures in Farmington                 16

  7.   Average Gross Working Level in Buildings by
       Type of Construction Material                           16

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                          ACKNOWLEDGMENTS

     The authors appreciate the efforts of Messrs.  Ray Baca,
Jack Ellvinger, and Richard Mitzelfelt for operating the Radon
Progeny Integrating Sampling Units, and the cooperation of the
various homeowners in allowing the measurements to  be made in
their houses.
                                VI

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           WORKING LEVEL SCREENING SURVEY OF STRUCTURES
            CONSTRUCTED OF MATERIALS CONTAINING PUMICE

INTRODUCTION AND BACKGROUND
     Pumice, produced from open pits northwest of Santa Fe,
New Mexico, is widely used throughout the southwest as a light-
weight aggregate for making concrete blocks. This pumice is known
to have a slightly elevated concentration of the naturally-
occurring uranium decay chain radionuclides.  Consequently, a
                                                  *
potential exists for radiation exposure from radon  progeny to
people living or working in buildings which contain this material.

     This matter first came to the attention of the Office of
Radiation Programs - Las Vegas Facility (ORP-LVF) during the
decontamination of the inactive uranium mill site at Shiprock,
                                                 **
New Mexico.  Radon progeny levels (working  level)   were monitored
extensively in a training building near the site, and were found
to be significantly elevated, averaging greater than 0.02 WL  (net
above background) on an annual basis.  At first, it was suspected
that tailings or other contaminated material from the mill site
had been used in the construction of this building.  However,
extensive surveys of the building proved that this was not the
case, but rather that the activity was in the concrete block
walls of the building.  The gamma exposure  rate throughout the
building was also elevated, increasing near the walls.  Further
investigation revealed that numerous concrete block buildings in
Shiprock, Farmington, Santa Fe, and in Durango, Colorado, also
contained block having elevated gamma exposure rates. The details
of pumice block production, use, and distribution are not well
known at this time although it is understood that pumice is
shipped widely throughout the southwestern United States.
*    In this report, the term "radon" refers to radon-222.
**   The working level is defined as any combination of radon
     daughters in one liter of air that will result in the
     ultimate emission of 1.3 x 10s MeV of potential alpha
     energy.

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     In 1976, the New Mexico Environmental Improvement Agency
(EIA) (now the Health and Environment Department) requested that
ORP-LVF conduct a survey of block buildings in the Santa re area
in order to further evaluate any potential radiation exposures,
and to provide them with information to assist in a decision as
to whether EIA regulation of the pumice, or the block products
made from it, was necessary.

SURVEY METHODS
     Instruments for measuring the radon daughter concentrations
(in units of working level) were loaned to the EIA.  These instru-
ments, formally known as the RPISU (Radon Progeny Integrating
Sampling Unit), are designed to measure the alpha particle energy
from airborne radon progeny, or daughters.  This alpha energy is
then converted to working level units, a commonly-used measure of
the health hazard from the radon progeny.  Unlike most working
level samplers, the RPISU measures the average, or integrated,
working level over a period of days, rather than taking an
instantaneous reading.

     A small pump pulls air through the detector head, which
consists of a millipore filter in close proximity to two TLD
chips.  The particulate radon daughters are trapped on the filter
paper.  As the short-lived daughters decay, their alpha energy is
deposited in the thermoluminescent dosimeter, or TLD, adjacent to
the filter.  A second TLD, shielded from the filter by a metal
washer, responds to the more penetrating gamma radiation from
external background.  The reading on the second (gamma) TLD is
subtracted from that on the first one Cthe alpha TLD) to give a
net reading due to alpha energy from the filtered radon daughters.

     The TLD material has the property of absorbing radiation
energy, then emitting a proportional amount of light when it is
heated later under controlled conditions.  Therefore, the detector
heads are sent back to the EPA laboratory, where they are taken

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apart, the TLD's removed, and "read out" in a special instrument
to measure the amount of emitted light, and consequently the
amount of radiation energy, absorbed during the sampling period.
Knowing the radiation energy absorbed and the volume of air
sampled, the average working level during the sampling period can
be calculated.
     Samples were collected in nine buildings in the Santa Fe -
Espanola area selected by the EIA staff.  The selection criteria
were a) that the building be known to be of pumice block construc-
tion, and b) that the owner/occupant be willing to participate in
the study by allowing the sampling units to be operated in the
building.
     Seven of the nine buildings were residences and two were
office buildings.  Five of the structures, identified as Locations
#50, 53, 56, 57, and 58 in Tables 1 and 2, were in Santa Fe
(elevation 6,900 feet), while four (#51, 52, 54, and 55) were in
the Espanola area (average elevation about 5,600 feet).  Locations
#55 and 58 were the office buildings, which had refrigerated air
conditioning.  None of the residences had air conditioning.  One
house (#53) was of frame/stucco construction and was selected as
a background house.   In the remaining buildings, all or most of
the walls were constructed of block containing pumice.
     Location #54 was sampled more intensively than the other
houses because different parts of it had been constructed of
different materials, as shown in Table 2.  It was thought that
samples from different rooms of this house might provide relative
indications of the working levels originating from the different
types of construction materials.  The pumice block and adobe
slump block rooms had just been built when this survey was made,
and these rooms were not finished, although they were completely
enclosed.  The doors, windows and roof were in place; however,
the concrete floor had not yet been poured.  The room built of
adobe slump block was closed off entirely from the rest of the
house at the time the samples reported here were taken.

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     Sampling times of about one week [approximately 168 hours)
were proposed.  This was not always attained and the actual
sampling times ranged from extremes of 33 hours to 628 hours.  A
total of 33 valid samples were collected during the period June
7, 1976 through May 20, 1977.

     During May 1976, gamma exposure rate measurements were made
in the selected buildings using a Reuter-Stokes Model RSS-111
Pressurized lonization Chamber (TIC) and a Baird-Atomic Model NE-
148A scintillometer.  Readings were taken in the center of each
room of the houses, and an outdoor reading was taken to serve as
background.  The type of construction material and the heating/
cooling system for each building was recorded.

     Samples of the unprocessed pumice from two commercial pits
near Santa Fe and samples of two block products were collected
and analyzed for the naturally-occuring radionuclides.   The
product referred to in this report as "pumice block" resembles a
standard concrete block and had dimensions of 8" x 8" x 16".  The
block referred to as "adobe slump block" is colored and cast with
an irregular surface to resemble authentic adobe bricks.  These
blocks are cast in a variety of sizes and shapes, and are widely
used in masonry construction because of their desirable visual
effect.  The block which was sampled measured 4" x 8" x 16".
According to the block manufacturer, the adobe slump and the
pumice blocks contain 40 and 65 percent pumice respectively.

RESULTS AND DISCUSSION
     The individual working level results for the Santa Fe area
are shown in Table 1.

     The working level values are calculated to five decimal
places, resulting in three or four significant figures for these
particular values.  When the values are averaged Ce-g-> in Table
2), the last figure is dropped, which is more indicative of the
accuracy and precision of the measurement system.

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TABLE 1.   INDIVIDUAL WORKING LEVEL RESULTS FOR STRUCTURES
          IN THE SANTA FE-ESPANOLA AREA
Location
and Run #
50-01
50-02
50-04
51-01
51-02
51-03
52-01
52-02
53-01
53-02
53-03
54-01Y
54-01W
54-01X
54-02X
54-02Y
54-03Y
54-04Y
54-05Y
54-01Z
55-01
55-02
55-03
55-04
56-01
56-02
57-01
57-02
57-03
57-05
58-01
58-02
58-03
Date Start
06/07/76
09/22/76
05/18/77
06/07/76
07/26/76
03/07/77
06/16/76
03/14/77
06/15/76
08/17/76
01/17/77
07/01/76
12/16/76
12/07/76
04/27/77
12/07/76
12/16/76
12/23/76
04/11/77
12/23/76
07/15/76
08/02/76
02/28/77
03/28/77
07/06/76
10/13/76
08/26/76
01/06/77
03/04/77
04/13/77
07/27/76
10/26/76
12/30/76
Date Finish
06/15/76
09/30/76
05/20/77
06/16/76
08/02/76
03/14/77
06/22/76
03/21/77
06/22/76
08/24/76
02/03/77
07/15/76
12/23/76
12/14/76
05/11/77
12/14/76
12/23/76
12/28/76
04/17/77
12/28/76
07/26/76
08/09/76
03/04/77
04/04/77
07/27/76
10/15/76
09/21/76
01/17/77
03/13/77
04/18/77
08/17/76
11/05/76
01/17/77
Sampling
Time (Hours)
165.3
39.3
33.1
211.5
33.9
239.1
146.7
70.5
169.1
55.7
384.4
326.5 .
155.9
150.1
339.5
150.2
155.8
121.1
131.0
121.0
197.5
100.9
97.4
143.9
254.6
48.4
628.3
269.2
210. 5
120.0
501.4
237.1
385.0
Working Level
.00283
.00869
.00675
.00182
.00133
.00233
.00310
.00200
.00255
.00228
.00392
.01559
.01719
.01884
.00985
.01511
.01039
.01346
.00853
.01379
.00616
.00790
.00263
. 00198
.00276
.01569
.01068
.00870
.00563
.00660
.00150
.00227
.00349

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           TABLE  2.   SUMMARY OF WORKING LEVEL RESULTS  AND PERTINENT  PARAMETERS
                      FOR STRUCTURES  IN THE  SANTA  FE  -  ESPANOLA AREA
Location Number of WL
Measurements
50
51
52
53
54 W
X
Y
Z
55
56
3
3
2
3
1
2
5
1
4
2
Average WL Average WL
(Gross) (Net)*
0.0061
0.0018
0.0025
0.0029
0.0172
0.0143
0.0126
0.0138
0.0047
0.0092
0.0032
-0.0011*
-0.0004+
-0-
0.0143
0.0114
0.0097
0.0109
0.0018
0.0063
Average Net*
Gamma Exposure Construction
Rate (yR/hr) Material
2.1
2.4
1.6
0.6
1.0
2.0
3.0
0
1.5
0.5
Pumice block
Pumice block
Pumice block
Frame/stucco
Original adobe
Pumice block
Adobe slump
block
Frame/stucco
Adobe slump
block
Pumice block/
Remarks

Block walls reportedly
filled with pumice
insulation

Background house




Office building with
refrigerated A.C.
Apartment - common
57
58
0.0079
0.0024
 0.0050
-0.0005
   2.6
   Not
measured
frame


Basement-
pumice block
Upper story-
frame

Pumice block
walls of block,
others frame

 Samples collected
in basement
Office building
with refrigerated
A.C.
 Obtained by  subtracting the average WL  from Location #53 from the  gross average WL at the other locations.
 Negative net WL values were obtained  because the "background" WL was larger  than the measured WL at these
 locations.
 Obtained by  subtracting outdoor gamma exposure rate from average (or individual room, in case of
 Location 54)  indoor gamma exposure rate.  The
 with a pressurized  ionization chamber.
                   exposure rates reported here were measured

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     As mentioned above, minimum sampling times of one week were
proposed.  This is derived from the Grand Junction experience,
where a minimum sampling time of 100 hours was required in order
for a sample to be considered valid for averaging into the annual
average working level estimate.  The reason for this requirement
was to avoid the possibility of including samples collected under
non-representative conditions (e.g., unusual ventilation condi-
tions or abrupt weather changes) which might unduly bias the
average working level.  Samples of less than 100 hours duration
were sometimes included in the average by time weighting all
samples in the series, rather than using the usual arithmetic
average.   It was felt that this method would avoid undue bias
from the "short" samples.

     Due to various operational problems in this study, a few of
the samples were considerably short of the 100-hour goal.  Both
time-weighting and arithmetic averaging were tried with the data
in Table 1.  In only two cases  (Locations 50 and 56) were signifi-
cantly different results (25-50 percent lower) obtained by the
time-weighting method.  Therefore, because of the relatively
small number of total samples, the "short" samples were retained,
and the arithmetic average was used for all locations.

     Table 2 summarizes the following Santa Fe area data: gross
average working level at each location; the "net" average working
level, obtained by subtracting the presumed background working
level from the gross working level at each of the other locations;
and the net indoor gamma exposure rate, obtained by subtracting
the outdoor gamma exposure rate from the average indoor gamma
exposure rate.  (Outdoor gamma exposures varied from 11 to 16
yR/hr, with a mean and standard deviation of 14.6  1.6 for the
eight locations measured.)  Table 3 shows the analytical results
for the two pumice and the two block samples.

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                    TABLE 3.   RADIONUCLIDE CONTENT OF PUMICE AND BLOCK


                    Concentration (pCi/gram  two-sigma counting error)



    Sample          U-258       U-254       U-255       Th-250      Th-252        Ra-226

Pumice #1         5.4 1.1    5.5 1.1    0.23 0.64   5.2  .36   4.0   .32     6.1    .45


Pumice #2         5.5 1.2    5.6 1.2    0.18  .056  4.2  .28   3.7   .27     5.6    .43


Adobe Slump Block
(40% pumice)*     1.7  .15   1.6  .15    .056 .010  1.4  .057  1.2   .054   2.2    .28


Pumice Block                                                 **              A*
(65% pumice)*     2.8  .18   2.2  .069   .18  .019  <0.042       .022.0063  3.4    .34
 *  As reported by manufacturer

 ** Thorium analyses believed to be in error on this sample

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     The data in Table 3 show that the radionuclide content of
the pumice is definitely higher than normal background levels,
which are generally in the approximate range of Q.5 to 2 pCi/gram
for most common mineral building materials.  The nuclide concen-
trations in pumice from the two pits are not statistically
different, and the uranium chain radionuclides are approximately
in equilibrium.

     The radionuclide concentrations in the block products are
not greatly different from the normal background levels mentioned
above, although the radium-226 values are at the upper end of
this range.  The radionuclide concentrations in the two types of
block are 30 to 50 percent lower than those which would be calcu-
lated from the manufacturer's stated percentage of pumice in the
block.  This may be due to the fact that the data in Table 3 are
on a weight basis, whereas concrete mix is usually proportioned
on a volume basis.  Since the pumice has a lower density than the
sand and gravel aggregates, activity in the pumice would therefore
account for a lower percentage of the total activity on a weight
basis.

     In general, the working level results were quite varied.
Some correlation exists between working level and indoor gamma
exposure rate.  Very little correlation exists between working
level and type of pumice block or other construction material in
the building, the type of ventilation system, or the geographical
location.   These various items are discussed in more detail
below.

     In Figure 1, the average gross working level at each location
is plotted as a function of the net indoor gamma exposure rate.
(The data from two buildings in Shiprock are included in this
figure;  see the discussion under Other Data below.)

     The data points, except for location 56, were fitted with a
line (RL-2) by linear regression analysis.   Line RL-1 was fitted
                                8

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    0.1 
    0.07-
    0.05-
                                                             LEGEND

                                                      53 - LOCATION NUMBER

                                                      PB - PUMICE BLOCK

                                                      F- FRAME

                                                      ASB - ADOBE SLUMP BLOCK

                                                      S- STUCCO
UJ

UJ
_j

O
z
X.
tc
o
(A
V)
O

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through all of the data points except those for locations 56 and
53.  Location 56 was deleted from the analysis because its gamma
ray background measurement (taken outdoors) was probably increased
by a block wall near the measurement location.  Location 53 was
deleted because it contained no pumice block.  It appears, from
the available data for this area, that the gross working level in
structures containing pumice block may approach a value of 0.01 WL
when the net indoor gamma exposure rate is approximately 3 yR/hr.
Lines RL-2 and RL-1 have correlation coefficients of 0.72 and
0.73 respectively, which indicates a "fair" fit to the data
points.

     Three of the nine structures containing pumice block (two
houses and one office building) had average working level values
lower than the frame/stucco house which was selected as a back-
ground location.  Location #51, which had one of the highest net
gamma exposure rates measured, and was constructed entirely of
pumice block, was one of these.  Location #54, the house which
contained several different construction types, produced the
highest working level results measured in the Santa Fe area.  The
working levels were quite uniform from room to room in this
house, and did not seem to be influenced by the construction
material of the room sampled, although the gamma exposure rate
definitely was.  Three pairs of concurrent samples were collected
in this house during December 1976.  One sample from each pair
was collected in the adobe slump block room, and the other sample
from rooms having each of the other three types of construction
(see Table 1).  Perusal of Table 1 leads one to suspect that the
seasonal effect on working level overrides the effect due to
construction material in this house, although the data points are
insufficient to demonstrate this conclusively.  These results
appear to indicate that, given a radon source within a house, the
working levels throughout the house are relatively uniform,
regardless of the location(s) of the source.
                                10

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     Since the pumice block has higher radionuclide levels than
does the adobe slump block, one would expect buildings made of it
to have higher working levels.  The data, however, show that this
is not consistently the case.  For example, the three structures
having an average working level lower than the "background" house
were all built of pumice block.  The background house, of frame
and stucco construction, was selected as background because it
contained no block having elevated radioactivity concentrations.

     Neither geographical location nor elevation has a discern-
able effect on the measured working levels.  Both the highest and
lowest levels were found in the Espanola area, with the structures
in Santa Fe falling in between.

     Several factors come to mind which might influence the
working level in buildings of different construction, or con-
tribute to the apparent variations observed.  Frame houses,
particularly those in Santa Fe with its cold winters, are prob-
ably insulated.   Some insulation materials, such as rock wool,
are known to be manufactured from slag which may have elevated
radium levels, and are therefore a source of radon.  The sig-
nificance of this source is not presently well-known.  Frame
house interiors are also covered with either plaster or sheet
rock (dry wall), both of which contain gypsum which may have
slightly elevated radium levels.

     The working level in houses having internal radon sources
has generally been found to show a seasonal variation, increasing
in the winter and decreasing in the summer.  The summer reduction
may be due to increased ventilation for cooling, which increases
the rate of removal of radon and its daughters from the house.
To investigate this effect in this case, the data for all locations
were summarized by month, and the mean WL was plotted as a function
of time of year.  The typical seasonal variation is not readily
apparent from this- plot.  Undoubtedly there are an insufficient
                                11

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number of data points available to expect a valid evaluation of
this variable, considering the other potential variables involved.

OTHER DATA

     Other information relating to the pumice situation has been
collected by ORP-LVF.  Some data have been collected specifically
to evaluate the pumice situation; other data have been collected
during surveys of buildings related to inactive uranium mill
sites, as discussed in the Introduction.  The two towns where
pertinent samples have been collected are Farmington and Shiprock,
New Mexico.  These two sets of data are discussed separately.

Shiprock

     Table 4 summarizes the following Shiprock area data: gross
average working level at each location; the  'net' average working
level obtained by subtracting a working level from a nearby
structure having no pumice used in its construction; and the net
indoor gamma exposure rate.

     The pumice block building in Shiprock which initiated the
investigation of the problem has had continuous WL measurements
made in it for over one year.  This building (location 75) is
close to location 76 and both are sometimes  immersed in the
radon-222 plume from the tailings piles on the former Shiprock
uranium mill site.  Because of the relatively large distance
between the locations and the tailings piles (approximately 760
m), both are subject to the same radon-222 concentrations from
the plume.   The average net WL for location  75 was determined by
subtracting the average gross WL for location 76 from it.  In
order to estimate tailings pile radon contribution to the average
gross WL for location 75, the average gross WL for location 73
was subtracted from location 76.   The adjusted WL for location 76
was then subtracted from location 75.  Th.e adjusted gross WL
results for location 75 was 0.26 WL and is plotted in Figure 1.
                               12

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       TABLE 4.  SUNMARY OF WORKING LEVEL RESULTS AND PERTINANT PARAMETERS FOR STRUCTURES  IN THE
                 SHIPROCK, NEW MEXICO AREA

                                                            Average Net
Location
Number
*
73
67
*
76
75
68*

71
Number of WL
Measurements
3
7
3
13
5

5
Average WL
(Gross)
0.0031
0.0041
0.0094
**
(O.OC63)
0.032
**
(0.026)
0.0025

0.0048
Average WL Gamma Exposure
(Net)* Rate UR/hr
 No data
0.001 1.4
 No data
0.023 3.4
 No data

0.0023 No data
Construction
Material
Metal building
Pumice block
Frame building
Pumice block
Frame  metal

Pumice block
Remarks
Industrial -Near
Location 67
Public building
Near Location 75
Training building
House trailer
near Location 71
Business
*   Locations 73, 76, and 68 are backgrounds for each of the three location pairs listed.
**  Gross average working level adjusted for radon from the tailings pile.

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     Locations 73 and 67 are constructed from different types of
materials and WL samples were selected to cover approximately the
same time periods for comparison.  Very little difference in
their Wl values was observed, even though location 67 is con-
structed from pumice block.  The reason for this may be that
location 67 is subject to heavy outside personnel traffic which
results in increased dilution of the indoor air.

     Locations 68 and 71 are close to each other and are also
subject to the tailings pile radon-222 plume.  Although location
71 is constructed from pumice block, its average gross WL is
relatively low.  The reason for this is that it is a fast food
establishment and is subject to heavy traffic like location 67.
The detailed WL data for Shiprock are not included in this report,
as they will be published elsewhere.

Farmington

     A preliminary working level screening survey was made of
buildings in Farmington during the period April 6 through July 19,
1976.   The samplers were operated by EIA staff based in Farming-
ton, and the sampling had to be terminated by EIA in July because
of the press of other duties at that time.  Samples were collected
in 10 buildings, as shown in Table 5.  No gamma exposure rate
measurements were made in these buildings to confirm that they
were constructed from block containing pumice except for location
900.  The use of pumice block at this location was confirmed with
a gamma scintillometer survey meter.  The working level data are
summarized in Table 6 with a description of the use and type of
construction material for each building.  None of the buildings
had refrigerated air conditioning.  Because of the paucity of the
data, and in the absence of gamma surveys for some degree of
confirmation, no "background" value has been assumed for Farming-
ton.  As Before, considerable variation of working level within
construction type was observed.  The lowest single value measured
was in a block structure, and the highest was in a frame/stucco
                                14

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TABLE 5.  INDIVIDUAL WORKING LEVEL RESULTS FOR
          STRUCTURES IN FARMINGTON
Location
900-01
900-02
900-03
901-01
901-02
901-03
901-04
901-05
902-01
903-01
904-01
905-01
906-01
906-02
907-01
908-01
909-01
Date Start
04/06/76
04/08/76
04/15/76
04/09/76
04/12/76
04/16/76
04/21/76
04/26/76
05/04/76
05/19/76
05/19/76
06/06/76
06/15/76
06/21/76
06/21/76
06/29/76
07/06/76
Date Finish
04/08/76
04/15/76
04/19/
04/11/
04/16/
04/21/
04/26/
04/29/
05/137
OS/31/
05/317
06/14/
06/18/
06/29/
06/29/
07/06/
07/19/
76
76
76
76
76
76
76
76
76
76
76
76
76
76
76
Sampling Time Working
(Hours) Level
32.
95.
97.
28.
57.
28.
30.
33.
201.
271.
290.
194.
67.
152.
190.
143.
210.
6
4
9
8
5
7
5
5
1
6
5
8
8
3
7
0
2
.00829
.00428
.00537
.00254
.00160
.00263
.00365
.00232
.00463
.00338
.00906
.00232
.00220
.00256
.00415
.00313
.00239
                     15

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         TABLE  6.   WORKING  LEVELS  IN FARMINGTON BUILDINGS
Location
Number
900
901
902
903
904
905
906
907
908
909
Number of WL
Measurements
3
5
1
1
1
1
2
1
1
1
Gross WL
Measured*
0.0060
0.0025
0.0046
0.0034
0.0091
0.0023
0.0024
0.0042
0.0031
0.0024
Type of Building
Office
Residence
Residence
Residence
Residence
Residence
Office
Swimming Pool
Residence
Commercial
Construction
Material
Pumice block
Block**
Adobe
Frame/stucco
Frame/ stucco
Frame/ stucco
Block*
**
Block
Frame/stucco
Red brick
*  This is the arithmetic  average at locations where more than one sample
   was collected
** These buildings are assumed  to be pumice block, but were not confirmed
   with gamma surveys (see text).
   TABLE 7.   AVERAGE GROSS WORKING LEVEL BY TYPE OF CONSTRUCTION MATERIAL
Construction Material
No. of Locations   No.  of Samples  Average WL
Santa Fe - Espanola
 (excluding #54 and 56, which had mixed construction materials)
      Pumice block
      Frame/stucco
Farmington
      Pumice block
      Frame/stucco
      Brick
      Adobe
Combined
      Pumice block*
      Frame/stucco
   6
   1

   4
   4
   1
   1

   9
   5
18
 3

11
 4
 1
 1

25
 7
0.0042
0.0029

0.0038
0.0036
0.0024
0.0046

0.0040
Q.Q032
   Includes adobe slump block
                                    16

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building.  It should also be pointed out that these data do not
represent an annual average, since all the samples were collected
during the spring and early summer, and would therefore be
expected to be lower than winter samples.

     The average working level, by type of construction material,
has been summarized in. Table 7 for the Santa Fe - Espanola area,
for Farmington, and for the two areas combined.  Buildings con-
taining more than one major material were deleted from this
summary.  The number of locations and of samples for each type of
construction material is also shown.  While the Farmington and
Santa Fe data are not strictly comparable for a number of reasons,
the average WL value in the two major types of construction
sampled  (pumice block and frame/stucco) are quite close together
and probably are not statistically different, considering the
working  level ranges observed within a given structure and
between  structures of the same type construction.  Furthermore,
the difference in working level between the two types of construc-
tion for the combined areas is also probably not statistically
significant.

COMPARISON OF RESULTS WITH STANDARDS

     Historically, the only U.S. standard for radon progeny
levels in residential or commercial buildings has been the Surgeon
General's Grand Junction guidance for houses containing uranium
mill tailings. This guidance is summarized as follows:

     Annual Average Net WL             Recommendations
       Less than 0.01          No action indicated
       0.01 - 0.05             Remedial action may be suggested
       Over 0.05               Remedial action indicated
                                17

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     Although this guidance gives some perspective, the present
data cannot be compared to it directly for several reasons.
These are:

     1.    The Surgeon General's guides were promulgated for use
          in a specific situation only, which is different from
          the pumice block situation.

     2.    Reliable background data are not available for the
          present situation.   It seems evident that the measured
          working levels are influenced by variables other than
          the one under investigation, thus making the selection
          of a valid "background" location(s) difficult.

     3.    The annual average working level for most of the
          Santa Fe/Espanola locations is questionable, since the
          samples were generally too few and/or too erratically
          spaced over time.  Although the annual average for
          individual locations may therefore be questionable, it
          should be noted that the total number of samples were
          fairly well distributed over the year.

CONCLUSIONS AND RECOMMENDATIONS

     1.    The results from this screening survey are insufficient
          to allow definite conclusions to be drawn regarding the
          potential health hazards which may result from the use
          of pumice in building block.  There is some indication
          that the use of pumice block may increase the working
          level in the structure.  However, this effect is so
          small that it is difficult to separate it from the
          variations in background and from the variability
          caused by other parameters.

     2.    Specific unanswered questions include the definition of
          "background" working level, the definition of the
                               18

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     annual average working level in most of the buildings
     measured,  and an evaluation of other parameters which.
     possibly Cor probably] affect indoor working levels.
     These include the ambient radon concentration from
     natural sources and its variability, other possible
     radon sources from other building materials Ce-g-> rock
     wool insulation), specific ventilation practices in
     individual buildings,  etc.

3.    Gamma exposure rate measurements inside a building
     appear to give some indication of the measured working
     level, to the extent that gamma surveys could be used
     as a screening tool.

4.    All the working level  measurements which have been made
     are in the categories  of "No action indicated" or
     "Remedial action may be suggested" under guidance which
     has been promulgated by the Surgeon General, although
     this guidance is for use in a different situation, as
     discussed above.

5.    On the basis of the data currently available, it does
     not appear that either remedial action or licensing of
     the pumice material is immediately warranted.  However,
     it is recognized that  use of the pumice in construction
     materials is widespread, and although individual
     exposures may be small, the potential aggregate popula-
     tion exposure may be sufficiently significant to
     warrant consideration for control in the future.
6.    Because any increase in working level due to pumice
     block use is small, a sampling program to establish a
     meaningful numerical value for the increase would have
     to be quite extensive, involving more locations,
                           19

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     samplers,  and samples than this screening survey.   It
     would also have to be much more comprehensive in order
     to provide a satisfactory definition of the variables
     described  above.

7.    An adequate population dose assessment for the pumice
     use would  require, in addition to the sampling mentioned
     above,  more information than is currently available
     regarding  the use and distribution of the pumice block,
     e.g., the  number  of structures containing it, the  types
     of structures,  and their geographical distribution.   It
     would also require a more detailed evaluation of the
     variability of the radioactivity content of pumice from
     different  pits  and different places within the pits.
                           20

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                               TECHNICAL REPORT DATA
                         (Please read Instructions on the reverse before completing)
1. REPORT NO.
   ORP/LV-78-6
                                                     3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
                                                     5. REPORT DATE
   Working Level  Screening Survey of Structures
   Constructed of Materials Containing Pumice
                        MAY  1978
            6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)

   R. L. Douglas, J. M. Hans,  and T. A. Wolff
            8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
   U.S. Environmental Protection Agency
   Office of Radiation Programs-Las Vegas Facility
   P. 0. Box 15027
   Las Vegas, NV 89114
                                                     10. PROGRAM ELEMENT NO.
            11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
   Same as above
                                                     13. TYPE OF REPORT AND PERIOD COVERED
                                                                 Final
                                                     14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT                                                           '      "

        This  report  describes  the results  of a  screening  survey conducted
   in several  northern  New Mexico communities to  estimate  the levels  of
   radon progeny (working levels) in building,  constructed of materials
   containing  pumice.   This locally-produced material is  used as a
   lightweight aggregate in concrete blocks, and  contains  slightly
   elevated  levels of natural  radionuclides.

        The  screening  survey results indicate that  the use of pumice
   block may  increase  the working level  in the  structure,  although  the
   effect  is  so small  that it  is  difficult to separate it  from background
   variations  and from  the variability caused by  other parameters.
17.
                            KEY WORDS AND DOCUMENT ANALYSIS
                DESCRIPTORS
                                         b.lDENTIFIERS/OPEN ENDED TERMS
                        c. COSATI l-'ield/Group
   Radon Isotopes
   Natural Radioactivity
   Pumice  -  lightweight aggregates
Radon progeny
Working level
    1802
    1808
    0807
18. DISTRIBUTION STATEMENT
   Release to  public
19. SECURITY CLASS (ThisReport!
     Unclassified
21. NO. OF PAGES
    27
                                         20. SECURITY CLASS (Thispage)

                                              Unclassified
                                                                 22. PRICE
EPA Form 22201 (Rev. 4-77)   PREVIOUS EDITION is OBSOLETE

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United States
Environmental Protection
Agency
Office of Radiation Programs
Las Vegas Facility
PO Box 15027
Las Vegas NV  89114
Official Business
Penalty for Private Use
S300
Postage and
Fees Paid
Environmental
Prelection
Agency
EPA 335

tit]
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