United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S7-84-093 Nov. 1984
Project Summary
Evaluation of Waterborne
Radon Impact on Indoor Air
Quality and Assessment of
Control Options
Albert P. Becker III and Thoma
> M. Lachajczyk
This research program had two objec-
tives: (1) evaluation of watei borne
radon impacts on indoor air quali :y, and
(2) assessment of available control
technologies to limit indoor exposures
to radon and its decay products.
The report reviews radon's physical,
chemical, and radiological properties;
summarizes its decay chain; and jives a
synopsis of health risks, existing regu-
lations, and recommendation!! con-
cerning exposure to radon and progeny.
Although the report is primarily con-
cerned with air concentrations o1: radon
and progeny resulting from waterborne
sources, other potential sources (home
subsurface, construction materials,
fuel, and ambient air) and their po tential
impacts on indoor air quality are also
discussed.
The report is the result of a litorature
search to identify and summarize re-
search by investigators in the U.S. and
abroad concerning the concentre tion of
waterborne radon (Cw) and its ef feet on
the indoor air concentration of radon
(Ca). Major factors that influence Ca/Cw
(including ventilation rate, water trans-
fer efficiency, water use rates, and
volume of the home) are examined.
Sensitivity analyses are conducted to
mathematically define a representative
value for Ca/Cw (0.7 x 10~4) and its
reasonable bounds (0.17x10 4to 3.5 x
10-'}.
The report also assesses reported
techniques for removing radon from
water or indoor air. Techniques evalu-
ated for removing radon from water
include decay, aeration, and granular
activated carbon. Techniques evaluated
for removing radon and/or progeny
from air include circulation, ventilation,
filtration, electrostatic precipitation.
charcoal adsorption, chemical reaction,
and space charging. Where the reports
examined include a sufficient amount
of information to do so, an evaluation of
the cost, efficiency, and practicality of
each technique is provided.
This Project Summary was developed
by EPA's Industrial Environmental Re-
search Laboratory, Research Triangle
Park. NC. to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering infor-
mation at back).
Introduction
Radon 222 (222Rn) is a naturally occur-
ring radioactive gas produced by the
decay of radium in the uranium decay
series. 222Rn undergoes radioactive decay
by emission of alpha particles with a
characteristic half-life of 3.82 days. 222Rn
decay products include a series of short
half-life (30 minutes or shorter) radio-
active isotopes commonly referred to as
radon "daughters" or radon "progeny."
All progeny are solid particles and are
chemically active metals, including 218Po,
2">Pb, 2"Bi, and 2'4PO.
Exposure to 222Rn and radon progeny
present in indoor air can occur from
various sources. Primary sources of 222Rn
in buildings are the soil adjacent to the
-------
foundation, construction materials, and
potable water supplies. Background 222Rn
in ambient air and presence in home
heating fuels are normally of lesser
importance. This report is concerned
primarily with waterborne sources of
222Rn, and their impacts on the indoor-air
quality of homes.
Small quantities of 222Rn can be found
m all groundwater from natural sources
asa result of decay of radium in waterand
diffusion from the rock and soil matrix
surrounding the water. Many investiga-
tors have quantified concentrations of
222Rn in water supplies. In the U.S.,
typical 222Rn levels m potable water
generally fall below 2,000 pCi/l, but
concentrations exceeding 300,000 pCi/l
have been noted. Specific areas with high
concentrations include portions of Maine,
New Hampshire, North Carolina, Texas,
Arkansas, Florida, and Utah.
«•
Health risks due to exposure to 222Rn
and radon progeny are mainly due to the
emission of alpha particles from 218Po and
214Po. Exposure of body tissues to radio-
activity entering the home in waterborne
222Rn can occurthrough both ingestion of
water and inhalation of 222Rn decay
products. Early studies focused on inges-
tion as the most important exposure from
an epidemiological viewpoint. However,
recent studies suggest that the dose to
the lung is the limiting factor in determin-
ing the maximum permissible concentra-
tion of 222Rn in water
Because of the importance of the
inhalation pathway, many investigators
have recently attempted to correlate
222Rn concentrations in water supplies
(Cw) with resulting concentrations in the
air of typical homes (Ca). Once defined,
this air-to-water concentration ratio (Ca/
Cw) can be used to assess health risks
associated with 222Rn concentrations in
water supplies.
This assessment of a representative
CaCwfor homes involves many considera-
tions. The quantities of 222Rn released
into a home depend on transfer efficien-
cies associated with each type of use
(which range from <10 to >98%) as well
as the quantities of water used. Once
released, 222Rn begins to decay to its
progeny, and the concentrations of 222Rn
and progeny in the home at any time
depend on the volume of the home and its
ventilation rate.
Exposures to 222Rn and its progeny can
be controlled either by removing 222Rn
from water supplies, or by removing 222Rn
and/or its progeny from air. Several
techniques are available.
Survey of Existing Information
The initial phase of this project included
a summary of the general concepts and
properties of 222Rn. Information presented
includes the physical and chemical prop-
erties of 222Rn; explanations of 222Rn
decay, progeny, and associated health
effects; a synopsis of federal regulations
on 222Rn; and presentation of the sources
and source strengths of 222Rn entering
homes. Figure 1 shows the radioactive
decay chains for 238U and 222Rn. Table 1
summarizes source contributions to the
indoor 222Rn concentration
Waterborne Radon and
Effects on Indoor Air Quality
An analysis is made of the factors that
affect the transfer of 222Rn from potable
water supplies to the indoorair, and(once
in the air) the factors that affect its
concentration. Major items discussed
include the water-to-air transfer efficien-
cies, factors that affect the indoor 222Rn
air level, a review of previous studies
relating the potable water 222Rn level and
that in household air, and the develop-
ment of a mathematical relationship
between the potable water 222Rn level
and that in household air
The transfer of a gas such as 222Rn from
a region of higher concentration (potable
water) to that of a lower concentration
(household air) is referred to as mass
transfer. Mass can be transferred by
random molecular motion in quiescent
fluids (molecular mass transfer) or^by
transfer from a surface into a moving
fluid, aided by the dynamic characteristics
of the flow (convective mass transfer).
These two phenomena control the rate at
which 222Rn can be out-gassed through
water use in typical household activities.
Major household activities that transfer
222Rn to the indoor air, along with typical
transfer efficiencies, are shown in Table
2.
Major factors which affect the 222Rn
mass transfer include: (1) increasing the
area of the water-to-air interface (e.g., by
using a spray) increases the mass transfer
across the boundary layer and (thus)
increases the transfer efficiency, and (2)
increasing the water temperature results
in greater 222Rn transfer efficiency.
Major factors found to affect the indoor
222Rn air level (assuming the transfer of
222Rn from potable water is the only
source of interest) include the concentra-
tion of 222Rn in the potable water, the
average transfer efficiency of 222Rn from
water to air, the types and volumes of
household water use, the ventilation rate
of the house, and the volume of the
house. Based on a thorough review o
literature, the following values were
assumed typical for four of these major
parameters:
f = 0.55 (transfer efficiency
of radon from water to
air),
A = 1.0 hr~1 (ventilation rate
in air changes per hour),
Vhouse = 75,000 liters/person
(volume of house which
is equal to the volume
of an air change), and
Vw = 9.5 liters/hr/person
(household water use).
Available literature data relating pot-
able water 222Rn concentration (C») to
222Rn concentration in the household air
(Ca) are summarized in Table 3, along
with major experimental conditions or
assumptions. A thorough review of each
literature source is contained in the
report.
A mathematical relationship between
the potable water 222Rn concentration
and resulting concentration in the house-
hold air was developed. The steady-state
equation relating the air/water concen-
tration ratio to four other major variables
is.
Ca/Cw = (f)(Vw)
where
Ca =
f =
(1)
Concentration of
222Rn in air
(pCi/l),
Concentration of
222Rn in water
(pCi/l),
Transfer
efficiency of
222Rn from water
to air,
Household water
usage (liters/hr),
Ventilation rate
mair changes per
hour (hr~1), and
Volume of the
house which is
equal to the
volume of an air
change (liters).
Table 4 presents typical, maximum,
and minimum reasonable values for each
variable. These variables are then arM
V
-------
Polonium 218
Radon 222
Lead 214
Thorium 234
Uranium 238
Protactinium 234
Uranium 234
1/4 Million Years
Thorium 230
77 Thousand Years
Bismuth 214
Minutes
Polonium 214
Lead 210
Radon's Progeny
Radon 222
Radium 226
Formation of Radon
Figure 1. Radioactive decay chains for uranium and radon.
(Source. LWRC83)
Table 1. Summary of Source Contributions to the Indoor Radon Air Concentration'
Source
Soil, Rock, Home Subsurface
Building Materials
Potable Water
Home Heating Fuels
Ambient Air
Calculated in
this Report
pd/l
0.01 -2.7
0.02 -0.7
0.1 - 13.6
0003 -00016
0.0001 - 3.5
Br83
pCi/l
0.05 - 2.4
0.005 - 0.5
0.2 - 28
-
-
afias;s House volume = 230.000 liters.
Ventilation rate = 1 air change per hour.
ranged in Equation (1) to generate the
minimum, typical, and maximum values
of the ratio Ca/Cw, as shown in Table 5.
These tables show that, under typical
conditions, the ratio Ca/Cw closely ap-
proximates the "10~4" empirical value
and for our assumptions is 0.7 x 10~4.
Conditions that generate a minimum
value for the ratio Ca/Cw are called
"conservative," and those that generate
a maximum value are called "liberal"
conditions.
Limited data are available in the liter-
ature that relate a measured Ca/Cw ratio
to the other major variables. Actual
monitoring data are summarized in Table
6 and graphically displayed in Figures 2
through 4. These figures, which also list
the boundary conditions established by
the assumptions listed in Table 5, show
that actual data closely approximate the
typical assumption plot that almost all
data fall within the boundary conditions
established by the liberal and conserv-
ative assumptions.
Thus, although one empirical number
cannot be selected as the water/air
diffusion factor, a range of numbers can
be defined based on reasonable boundary
conditions. This range has been shown to
vary from 0.17 x 10~4 to 3.48 x 10"4 under
typical conditions.
Control Technology Evaluations
The report discusses the applicability of
the various control technologies that are
available for removing 222Rn from water
sources and also for controlling airborne
concentrations of 222Rn and its progeny
after entering the home. An evaluation is
made of the cost, efficiency, and applic-
ability of each control technology where
sufficient information is available.
-------
Table 2.
Measured 222Rn Water/Air Transfer Efficiencies for Typical Household Activities
Activity
Transfer Efficiency (% "2Rn Released)
EPA77 Pa 79 Ge80 He81 He82
Laundry Washing:
Hot wash cycle (18 mm) with soap
Hot wash cycle (13 mm) without soap
Cold wash cycle (18 min) with soap
Cold wash cycle (18 min) without soap
Warm wash cycle (18 min) with soap
Cold wash cycle (11 mm) with soap
Cold wash cycle (4 min) with soap
Cold wash gentle-cycle with soap
Cold wash gentle-cycle without soap
Cold rinse regular cycle
Cold rinse gentle cycle
No specific description given
Dishwasher.
Wash Cycle
Rinse cycle
No specific description given
Bath Tub.
Hot water
Warm water
Cold water
No specific description given
Shower
Warm water
No specific description given
Sink
Warm water
No specific description given
Toilets
Tank
Bowl
No specific description given
Drinking and Kitchen
No specific description given
Cleaning:
No specific description given
Overall Weighted Average for All Household Uses
984±1.3
97.9±2.7
93 3±5.2
93 5±3.4
98.3
91.4
84.7
78.7
766
80.9±174
62.2
97.7±3 7
98.5±2.1
59.7
36.2
37.8
90' 90* 90'
98 98 98
47 30* 30'
71.2±4.7
91 63 65 65
28.3
4.9±11 3
23 6±6.5
30" 10-15'
30 30° 30'
30
90
625 52 59 59
'Estimated
Table 3.
Summary of Ca/Cw Literature Data
Source
UN77
He78
He79
Pa79
Ca
pCi/l
02
0.09
0.3
0.7
4.5
5.0
10O
2.4±1.2
2.6±0.7
10.3±1.6
3.9
3.3
0.18
0.42
pCi/l
1,000
100
3.000
9.000
60,000
85,000
85,000
60,000
1,480
24,810
87,430
32,670
10,000
10,000
(x 10'") Experimental Conditions/Basis
1 0 Series of assumptions: 4 people, water use = 1000
liters/day, 230,000 liters = Chouse, A = 1 hr~\ f=
9.0
1.0
0.78
0.75
0.59
12
A unknown, actual data based on
measurements of Ca in the same room as the
source. Led authors to conclude Ca/C» = 70~4
(0.4±0 2) A = 3 0 hr~^ 24 hr radon values in
(18±5) A = 1 1 /?r~1 these dwellings. Wrenn-
(4±2) ^ = 7.0/7/-~1 Spitz-Lundum measurements
0.45 A = 2.1 hr^
1.0 school, A = unknown
0.18 A=20hr~'\ V» = 23.3 liter s/hr
0.42 A = 10hr-'f f = 0.625
1.0.
Removal of Radon from
Water Sources
Major technology evaluated for 222Ftn
removal from water sources in homes
includes decay in a holding tank, aera-
tion, and granular activated carbon. A
detailed description of each technology is
included in the report. Table 7 summariz-
es available information concerning the
removal efficiencies, capital and operat-
ing costs, and practicality of each tech-
nique.
It was j udged that decay is not practical
for typical domestic situations due to the
long holding time and large storage
capacity required.
A comparison of aeration versus car-
bon adsorption for removing 222Rn from
potable water supplies, once the water
has reached the residence, leads to the
following conclusions.
1. 222Rn removal using aeration is
highly variable, and removal effi-
ciencies are highly dependent on
the system's ability to de-gas the
222Rn once aeration has taken place.
2. Potable water m the home would
have to be aerated in an isolated
well-ventilated area to adequately
disperse out-gassed 222Rn outdoors.
3. The initial capital cost, operating
cost, and maintenance of an aera-
tion system would be higher than
those of an activated carbon system
because of the use of motors and
compressors. The cost advantage of
granular activated carbon versus
aeration appears to hold true par-
ticularly for low to moderate influ-
ent 222Rn concentrations (less than
50,000 pCi/l).
4. More consistent and higher removal
efficiencies have been demonstrat-
ed for carbon adsorption. Literature
sources indicate that 62 to 99.8
percent of 222Rn can be removed
from water by carbon adsorption.
5. The operation of a carbon adsorp-
tion unit is judged to be easier than
that of an aeration system for
domestic operations.
Control of Indoor Air
Concentrations
Several treatment technologies can be
used to reduce the level of 222Rn and/or
progeny in indoor air. Technologies eval-
uated include circulation, ventilation,
filtration, charcoal adsorbers, chemical
reaction, and space charging. Each tech-
-------
Table 3.
Source
Ge80
Ka80
(Finland)
Mc80
NRC81
He81
(Continued)
C. C»,
pCi/l pCi/l
0.78 10,000
1.3 10.000
0.92 10.000
040 10.000
0.18 10.000
1 10.000
0.51 1.000
0. 1 1 1.000
0.05 1.000
001 1,000
035 1,750
0.04 700
0.18 2,000
0 10 2,000
unknown
unknown
unknown
0.5 158,000
3.2 164,000
0.6 152,000
2.0 158,000
47 / 68, 000
2.5 148.000
0.5
3.4 129,000
2 2 43,000
0.7
1.2 98.000
0.6
19.1 370.000
6 6
1 5 190,000
3.0
3.3 314.000
1.2
0 2 1,000
ca/cw
(x 10'* j Experimental Conditions/ Basis
078 A = 0.5 hr'' 1
1.3 A = 0.25 hr~'\
0.92 Vhou^= 1.4x1 05
0.40 VhoUM = 3.4x1 0s
0.18 I/house = 6. 6x1 0s
Vhouse = 4x1 05 liter
V» = 23.3 liters /hr
f = 0.625
A = 1 0 /i/-"1
1.0 Estimation Basis. Chouse = 200.000 liters
5.1
1.1
05
0.1
Calculated
2.0
0.57
090
0.5
Actual
Measurements
^ouse (liters) (hr"1)
150,000 0.25
340.000 0.50
340,000 1 0
680,000 2.0
1 75,000 0.25
340.000 1.0
340.000 0.5
500,000 1 0
1.4 Housewives and small children
0.6 Other persons.
0.87 Population weighted coefficients for
a/I of Finland.
0.032 Nova Scotia, Canada trailers, actual
0.2
0.039
0.13
0 2.4
0.17
0034
measurements
school
0.26 \ Conventional
051 > homes
0.16 J
0.12
0.061
0.52
0 18
0079
0 16
0.11
0.038
School
Conventional
homes
1 . 0 General statement
0.75±O. 1 Average of 1 8 homes in Maine.
1 9 52,000
1.7 17.000
3.2 27.000
0.7 6,500
4 5 28,000
3.0 18,000
<0.3 330
<0.3 330
<0 3 330
1.5 22.000
1.5 25,000
1.0 8,000
5.0 28.000
<0.3 330
3 8 52 000
0.85 17,000
1.6 27.000
0.35 6,500
2.0 28.000
1.0 18,000
037
1.0
1.2
1.2
1 6
1.7
9.1
9.1
9.1
0.68
060
0.13
0.18
9.1
0 73
050
0.59
0.54
0.71
0.56
Normalized to A = 1 hr~\ corrected
Graphically: (0.6 ±0. 1)x 10'" = Ca/C»
Add 25% for weak sources
(0.75±0. 1) x 10'' = Ca/Cw
nology is discussed in detail in the report.
TableS summarizes available information
on each treatment technology as it per-
tains to 222Rn and/or progeny removal.
Because the capital cost of household
control equipment is highly dependent on
existing heating, cooling, and duct work
systems and associated ventilation rates,
conclusions concerning the advantages
of one system over another are highly
site-specific.
Conclusions
1 . Concentration of 222Rn in water, at
concentrations exceeding about
1000 pCi/l, have a measurable
impact on indoor air quality.
2. Ca/Cw, the ratio of airborne 222Rn
resulting from water supplies to the
waterborne concentration of 222Rn,
has been measured as low as 0.032
x 1 0~4 and as high as 59.0 x 1 0"* in
individual homes.
3. Most measurements and estimates
of Ca/Cw reported in the literature
range from about 0.18 x 10~4to2.0
x10~4.
4. The value of Ca/C« m homes de-
pends primarily on homeventilation
rates; volume of the home; volumes,
types, and diurnal variations in
water use; and water-to-air transfer
efficiency. In addition, measure-
ment of Ca/Cw can be affected by
the types and locations of 222Rn
monitoring equipment used, indoor
humidity, meteorological condi-
tions, circulation systems and arch-
itectural style of the home, exper-
imental errors, and complications
due to non-waterborne sources of
222Rn entering the home.
5. The value of Ca/Cw as referred to in
this report expresses a time- and
volume-weighted average which
could be used to develop relation-
ships between cu mulative exposure
rates to residents of homes and
resulting health effects. Ca/Cwdoes
not evaluate short-term or site-
specific acute exposures.
6. Work reported by Hess (He82),
based on studies in 18 homes in
Maine, provides measured values
for Ca/Cw in experiments designed
to eliminate some of the variation in
Ca/Cwdue to ventilation rates, non-
waterborne sources, and monitor-
ing location. The authors report
Ca/Cw = (0.8 ± 0.2) x 10"" for Ca
measured by Wrenn detectors in
-------
Table 3.
(Continued}
Source
He82
C.
pCi/l
Cw
pd/l
Ca/C»
(x 10~4) Experimental Conditions/Basis
(0.8±0.2) Normalized to A - 1 hr~\ corrected
UN82
He83
229
(avg. 32
obs.)
78
(avg. 47
obs.)
592
(avg. 20
obs)
138.000
(avg. 20
homes}
138,000
radon bursts by 33% to account for
radon from all water
15 f=1.00(NEA78)
1.0 (Du76)
20.6 avg. Ca/Cw for 32 rooms, situations
where much water used (showers).
5.64 avg. Ca/C» for 47 rooms, situations
where little water used (cooking).
138.000 0.60 avg. Ca/C« for 20 living rooms,
situations where no water used(An78).
1 3 avg. Ca/Cn in 70 homes, discounting
other sources (not normalized for h).
Table 4. Variable Flanges
Parameter
f
Vw (liter/ hr/ person)
Chouse (liters/person)
A (air change/ hr)
Minimum
Values
0.25
4.75
37,500
02
Typical
Values
0.55
9.5
75,000
1.0
Maximum
Values
1 0
19
150,000
2.0
Table 5. Ca/Cw Range
fects than is 222Rn gas. The con-
centration of radon progeny in air
due to waterborne sources, meas-
ured in working levels, has not been
investigated to the extent that
Ca/Cw has.
10. 222Rn can be removed from water by
decay, aeration, or carbon adsorp-
tion. Efficiencies exceeding 90 per-
cent have been reported to be
achievable through each technique.
Based on cost, efficiency, and prac-
tical operability, carbon adsorption
appears to be the most advantag-
eous choice for most domestic
applications.
11. Removing 222Rn and/or radon pro-
geny from indoor air has been
demonstrated by circulation, venti-
lation, filtration, electrostatic pre-
cipitation, and charcoal adsorption.
Removal efficiencies of 50 - 95
percent have been reported. Re-
moval efficiencies depend on venti-
lation rates, circulation systems,
degree of plate-out occurring, hu-
midity, particle size distribution,
and other factors. Selection of
control systems for individual
homes, based on efficiency, cost,
and practicality, is highly site-
specific and would depend on the
heating, cooling, and circulation
systems already in place.
Parameter
f
V* ( liters/ hr/ person)
Chouse (liters/ person)
V*/Vhouse(hr-')
A (air change/ hr)
Ca/Cw
Conservative
Variables that
Generate Minimum
Ca/Cw
025
4.75
150.000
3.17 x 70~5
20
3.96 x 70~6
or
0.0396 x 10~*
Typical
Variables
0.55
9.5
75,000
1.27 x 10~"
1.0
697 x 7CT5
or
0.697 x 10~'
Liberal
Variables that
Generate Maximum
Ca/C»
1 O
19
37.500
5.07 x 10''
0.2
2.53 x 10~3
or
25.3 x 10~'
the living room of homes, with
ventilation rates standardized to
1.0 hr"1. The authors also report
Ca/Cw = 1.3 x 10"" without stand-
ardizing for ventilation rate.
7. Sensitivity analyses completed for
this report suggest that, when a
typical range of values for ventila-
tion rate, water-to-air transfer ef-
ficiency, and ratio of water use to
home volume are assumed, Ca/C«
may be expected to have an average
value of 0.7 x 10~4 and a range of
0.17x10"" to 3.5x10""
The value of Ca/Cw is likely to vary
diurnally over a range of approxi-
mately one order of magnitude in
most domestic situations due pri-
marily to sporadic water use, loca-
tion of monitoring sites with respect
of waterborne 222Rn sources, and
fluctuating ventilation rates.
Presence of radon progeny is more
directly responsible for health ef-
Recommendations
1. The value of Ca/Cw is based on theo-
retical calculations and/or meas-
urements at relatively few homes.
An expanded monitoring program,
using standardized monitoring tech-
niques in a cross-section of geo-
graphic areas of the U.S., may be
desirable.
2. Further monitoring, if conducted,
should be designed and implement-
ed to reduce and quantify uncer-
tainties in Ca/Cw which result from
sampling procedures, monitoring
locations, measurement of ventila-
tion rates, circulation patterns in
the home, meteorological influenc-
es, inadequate water use records,
diurnal and seasonal variations,
contributions from sources other
than water, etc.
3. Further research in the relation-
ships between the concentration of
radon in water and resulting con-
centrations of progeny in air would
provide valuable information
-------
Table 6. Actual Monitoring Data Illustrating the Relationship Between the Air-to-Water
Concentration Ratio and Other Major Variables
Source
Ge80
He81
He83
He79
No. of
Occupants
4
4
3
5
4
3
4
2
3
2
5
A
/7/-"1
0.25
1.0
0.5
1.0
20
0.5
0.5
0.5
0.5
04
03
1.0
30
1.1
1 0
2 1
Vw l/hou™ Actual Predicted (Eq. 1)
f l/hr 1 Ca/Cw Ca/Cw
052 37.1 f 75.OOO 2.0x10'* 4.4 xW*
0.52 37.1 340.000 0.57 x10~
0.52 278 340,000 0.90x70"
0.52 464 500.000 0.50x70"
0.37 x 70"
7 Ox 70"
7.79x70"
7.0fix 70"
0.57 x 70""
O.SSx 70""
0.48 x 70""
<7.Sx70"
7 67 x 70""
7 67 x 70""
08 x 70""
(4 ±2//x70"5
(1.8±0.5)x1Q-3
(42 ±06)x 70""
4.5 x 70"5
Legend
for"Liberal" assumptions
for "Typical" assumptions
for "Conservative" assumptions
O Ge80
O He81
a He83
O We79
Q
* Actual data refers to
data developed through
in situ monitoring
1E-7
0.01
Figure 2.
Air Change, 1 /hr
Actual monitoring data" showing relationship between air/water concentration
ratio and air change rate.
4. Exposure to progeny during periods
of close proximity to the waterborne
source has not been fully evaluated.
5. The cost, efficiency, and practicality
of various control technologies,
particularly for removing 222Rn and
progeny from air, have not been
firmly established.
References
An78 Annanmaki, M., 1979. "Measure-
ments on Radon in Finnish Dwellings,"
Fifth Meeting of the Nordic Society of
Radiation Protection, Visky, 1978, Insti-
tute of Radiation Protection, Helsinki.
Br83 Bruno, R. C., 1983. "Sources of
Indoor Radon in Houses: A Review,"
Journal Air Pollution Control Associa-
tion (JAPCA), Vol. 33(2), pp. 105-109.
Du76 Duncan, D. L, et al., 1976. "Radon-
222 in Potable Water," in Proceedings
of the Tenth Mid-Year Health Physics
Society Topical Symposium on Natural
Radioactivity in Man's Environment,
Saratoga Springs, NY, Rensselaer Poly-
technic Institute.
EPA77 EPA, 1977. "Radiological Qual-
ity of the Environment in the United
States, 1977," USEPA, Office of Radia-
tion Programs, EPA-520/1-77-009.
Ge80 Gesell, T F., et al. 1980. "The
Contribution of Radon in Tap Water to
Indoor Radon Concentrations," DOE
Symp. Ser. 51 (Nat. Rad. Env. 3, Vol. 2,
Conf. 780422), pp. 1347-1363.
He78 Hess, C. T., et al. 1978. "Invest-
igation of Natural Levels of Radon-222
in Groundwater in Maine for Assess-
ment of Related Health Effects," DOE
Symp. Ser. 51 (Nat. Rad. Env. 3, Vol. 2,
Conf. 780422), Houston, TX.
He79 Hess, C. T., et al. 1979. "Radon-
222 in Potable Water Supplied in
Maine: The Geology, Hydrology, Physics
and Health Effects," NTIS PB80-116
304.
He81 Hess, C. T., et al., June 1981.
"Investigation of 222Rn, 226Ra and U in
Air and Groundwaters of Maine, "NTIS
PB81-238552.
He82 Hess, C. T., et al., 1982. "Varia-
tions of Airborne and Waterborne Rn-
222 in Houses in Maine,"Environment
International, Vol. 8, pp. 59-66.
He83 Hess, C. T., et al., August 1983.
"Environmental Radon and Cancer
Correlations in Maine," Health Phys-
ics. Vol. 45(2), pp. 339-348.
-------
00? -
1.0E-3-.
10E-4-
c
0]
I
V
Hi
I
1E-5 ~
1E-6 -
1E-7
Legend
* » f vs p;— for "Liberal" assumptions
I "t f vs ^—lor "Typical" assumptions
Ca . .,„ . „
o——o / vs -f.— for Conservative assumptions
O Ge80
"Actual data refers to
data developed through
m situ monitoring
0.0 J
' r ' ' I^
0.1
Water Transfer Efficiency
Figure 3. Actual monitoring data" showing relationship between air/water concentration
ratio and water transfer efficiency
Ka80 Kahlos, H. and M. Asikainen,
1980. "Internal Radiation Doses from
Radioactivity of Drinking Water in Fin-
land," Health Physics, Vol. 39(1), pp
108-111
LWRC83 The Land and Water Resourc-
es Center, University of Maine at
Orono, 1 983. "Radon in Water and Air,
Health Risks and Control Measures,
Resource Highlights."
Mc80 McGregor, R. G. and L. A.
Gourgon, 1980 "Radon and Radon
Daughters in Homes Utilizing Deep
Well Water Supplies, Halifax County,
Nova Scotia, "J. Env. Science & Health,
A15(1), pp. 25-35.
NEA78 Nuclear Energy Agency (OECD),
1978. "Radiological Implications of
Natural Radioactivity in Building Mate-
rials: Physical Aspects," NEA (78) 12,
Pans.
NRC81 National Research Council,
1981 .Indoor Pollutants, National Acad-
emy Press, Washington, DC.
Pa79 Partridge, J E., et al., 1979. "A
Study of Radon-222 Released from
Water During Typical Household Activ-
ities," Final Report, NTIS PB 295 881,
pg. 33.
UN77 United Nations, Scientific Com-
mittee on the Effects of Atomic Radia-
tion, 1977. Report to the General
Assembly with Annexes: Sources and
Effects of Ionizing Radiation.
UN82 United Nations, Scientific Com-
mittee on the Effects of Atomic Radia-
tion, 1982. Report to the General
Assembly with Annexes: Ionizing Rad-
iation: Sources and Biological Effects.
8
-------
Legend
-— vs -^— for "Liberal" assumptions
0.07 -l
0.001 -
TO
tt
c
o
| 1 OE-4 •
c
1
S
TO
X
1E-5-
1E-6-
I/house Cw
Ca
—— vs ^— for "Typical" assumptions
,. — vs ^— for "Conservative" assumptions
I/house CW
Ge80
"Actual data refers to
data developed through
\r\ situ monitoring
1E-5
1.0E-4
0001
Figure 4. Actual monitoring data" showing relationship between air/water concentration
ratio and l/»/Chouse ratio
Table 7. Summary of Techniques to Achieve Removal from Water at Homes
Technology
Potential Removal
Efficiency 222Rn. %
Cost in 1983 Dollars
Annual
Capital O&M Comments
Decay in Holding Tank Up to 96 9-99.6
Aeration
Granular A ctivated
Carbon
20-96
62.1 -99 8
92 5 avg.
NA"
NA
Judged impractical due
to size requirements
$890-$ 1000 $60-$80
$431-$1500 $1O-$40 Cost dependent on
influent concentration;
judged easiest
to operate
"NA = Not available
-------
Table 8. Summary of Techniques to Remove 222Rn and Progeny from Air in Homes
Costs in
Potential Removal 1983 Dollars
Efficiency, % Annual
Technology
Circulation (fans)
Ventilation:
Natural
(open window]
Forced Air
Heating & Coo/ing
Centra/ Fan
(increase vent
rate 3. 7 times!
Combined ESP/ outside
exchange system
Ventilation
combined with
air-to-air heat
exchange
Air Cleaner
Filtration
Electrostatic
Precipitator
Charcoal A dsorber
Chemical
Reaction
Space Charging
222Rn Ftn Progeny
0 50-63
94 91
79 91
80 89
0 62"
34-87
0 <90
0 73-95
99
Capital O&M Comments
20-150 --* Assuming no ventilation
rate change
0 0 Increases ventilation rate by
factor of 11 : neglects
heat/cooling loss
0 0 Costs are routinely incurred
20-150 320 Annual costs for additional
heating (only) based on
doubling ventilation rates
1400 165+
100-1400 25-250 Costs depend on ventilation
rate achieved
..
Experimental
No information
"- - - insufficient data.
^Based on mathematical modeling
Albert P. Becker III, and Thomas M, Lachajczyk are with Envirodyne Engineers,
Inc., St Louis, MO 63146.
John S. Ruppersberger is the EPA Project Officer (see below).
The complete report, entitled "Evaluation of Waterborne Radon Impact on Indoor
Air Quality and Assessment of Control Options," (Order No. PB 84-246 404;
Cost: $14.50, sub/ect to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
10
'USGPO: 1984 — 559-111/10729
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