?a8®~iS02«2
Ra<3on Mitigation Choices in the Ur.itsd States
A acsapasiscKiit of Private arsfl Public
Sector Developments
Znvitonaetttal Protection Ajfrvsy
Reeearch Triangle Park* UC
'¦ Jen 80
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WW- (J-8 \ • Qtf
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EPA/600/D-SE/011
January 1988
RADON MITIGATION CHOICES IN THE UNITED STATES---
A COMPARISON OP PRIVATE AND PUBLIC SECiOR DEVELOPMENTS
By
Kelly A. Witter, David C. Sanchez, and Alfred B. Craig
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
VO
do
_s>
oo
EPA Project Officer
Kelly A. Witter
;-;pa
• ¦ anc' Chemical Libraries
\ 3ldg Room 3340
'"¦'''ijode 3404T
;.':-.itution Ave NW
•gion DC 20004
--'U 2-566-0556
AIR AND ENERGY ENGINEERING RESEARCH LAROKATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIROiriENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, NC 27711
REPRODUCED BY
J.S DEPARTMENT OF COMMERCE
NATtO.\'AL THCHttiUAL
INFGRKyVTlGN fir iWin?
-------
z
[TTwoiit wo.
I PA/600/D-38/01.1
XTITLE AMD bbpTIYLS
jRaaon Mitigation Choices in 'the United States--/,
Ccmpari;son oi Private and Public Ssctor
Developments
TECHNICAL KSPQK7 DATA
(Piease read Jntirucri&it on ikt nvwit befvn? completing}
3. REClS'tENT'S ACCESSION IVO.
. /£? & A U J.
0. REPOrtY DATE
January 1988
8. PGBFOKMtNG ORGANIZATION CODE
[? AUTMOfi(li)
Kelly A. Witter, David C. Sanchez, and
Alfred B. Craig
B. PEBFOHMING OHGANI2ATIQM REPORT NO.
i. PCKFORWilMG ORGANISATION NAM!; AMD APDa£B8
*o. program element mo.
See Block 12.
lf:"(fOTVAAtr/&MANr (m6~
NA (Inhouse)
12. SPONSORING AG£K'CV NAME AND AGGRESS
EPA, Office of Research and Development
Air sad'lSnergy Engineering Research Laboratory
Research Tx^anste Park, NC 27511
13. TYPE OF R£?QflT ANO PEtttOD COVERED
Journal Article; 12/87
1£. ftPONSOMINO A3KMCV CODE
EPA/600/13
E2.EuFj»LEMtir1iTARvp(OT(is ^SERL project officer ia Kelly A. Witter, Mail Drop 54, 919/541-
The paper compares private find public sector developments relating to
TTi'it1 on ufi.ifcigation in lbs U, S. In response to elevated radon levels in many U. S. hou-
ess, the FedorrJ and State governments and the private sector have undertaken muny
v&ritid mitigation and public information effortn recialthjg in a range of rac2o& reduc-
tion mstallp-tiona in the U. S„ Government- nporjeored research and development of
radon Aid Ligation techniquc-B in aingle-family detached houses is compared vith rc.rion
Eoitt^atisn approaches undertaken by the private sector. An attempt is also xnp.de to
coEnpar? prerniijgstion diagnosticc, the application of miti^aticn techniques to var-
ious substructure types, the crxormsT.ce of mitigation installations, and the cost of
the installations. The information collected inoxcatesj tha.t eubelab ventilation is the
asc33t ccmaioa technique in both public and private sector radon mitigation; however,
air-to-air hee.t exchangers and sealing are employed, more frequently in the private
sector than in government-sponsored mitigation.
17.
KEY WOROS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDfcf.'TIFICPIS/OPfeN ENDED T6FIW5
C. COSATi FfiliJ/GrOlip
Pollution Cost Analysis
Radon Ventilation
Atmosphere Con- Heat Exchangers
tsmination Control Sealing
Houses
Soils
Pollution Control
Stationary Sources
Indoor Air
Soil Gas
13 B
D7B
3GK
13 M
38G, GSM
14A
13A
13 H
1U. DISTRIBUTION STATtMCNT
Release to Public
EPA firm 2SS0.3 J3-73)
19. SECURITY CLASS {TKis Report)
Unclassified
21. wo. OF HAG£S
20. CICUR1TY CLASS (This pd£t)
Unclassified
22 PRICG
JJl
Pi ft j /*?• 9<
M'i .n tm^SSvmr i ¦!
-------
NOTICE
This document has been reviewed in accordance with
U.S. Environmental Protection Agency policy and
approved for publication. Mention of trade names
or commercial products does rot constitute endorse-
Eent or recomnendation for use.
ii
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RADON MITIGATION CMOfCES IN TKE UNITED STATES -- A COMPARISON OF
PRIVATE AND PUBLIC SECTOR DEVELOPMENTS
Kal ly A. Witter, David C. Sanchez# and Alfred E. Craig
Unitod Stctoo Environmental Protection Agoncy
Air and Ensr^y Engineering Heecmrch Laboratory
Research Triangle Pork, IsJorth Carolina 277ii
introduction
In rasponoo to olovcted levels at ration in aany hoiiaes
throughout tho U. S.» the FadereE and State governracnts and the
private sootor have undertaken n&ny varied caitigation and public
information afSorts resulting in a range of radon reduction
installations in tha U. S. Govorncaont rcponoored research and
doiaonstrotion of rndon siitigofcion techniquoo in ftinglo ffaaily
dot&ched houaoo is compared waf and tho cost of tha installations. Duo
to varying methods and QKtents of date. eol loction,, it is alton
difficult to ranks a direct eotapsiricon Isoiweon . El. tigafcSon
instil Iationr. obtained tfrois ditffforont oejuirccs. !n nwei? coacc,
tho information &vnigable ic prosontod, end a ewalifcatSv®
comparison io nado.
GOVEBMKENT SPQ^SCEED RADON JUT SCAT I CM
Govornraorit appreachura to ycdon tuiticntSen end raiiicat'on
rocfsareh dipcuscod in this pspcvr focyj on tt>& U. S. EnvircnoontaS
Protection Agency's (EPA) radon reduction fiold projects, EPA"a
House? Evaluation Proftrao VCJEP), and aoleatod ait£j&tlon
information from Stele radon pi-ogrecr;.
Tho objoctivo of EPA'a Radon flitiR&tieM RQaoarch Pro^rsts is
to develop end dumonotrato cost-e?foctive radon reduction csothoda
applicable to all house ^substructures typsa. To aecoraplirch this,
EPA's Office of Re.'soarch and Dave! opesant (GRD) io sponsoring
research and demonstration of selected radon sltigstion
techniques in housos in sovcral fiold projects. Currant and
completed fiold projects are iocntad in tho States of
Psnnsy 1 vanla, Wet# Jersey, Wow York, Maryland, Florida, Tennessee,
Alabama, and Ohio. The specific mitigation installations
discussed bolow apply to tha intermediate phasa and conplatsd
instat Iationn in 40 houaos in E&ctfirn Pcnnny! vanici, 10 housor; in
Clinton, Nsw Jorsoy, and 14 houtoa in the piedmont r&gion of Mew
Jersey. Current end planned BitiQation for tho other ongoing
fio!d projects, comprising approaiu:ctoIy SO houseu, is briefly
discussed.
EPA's Office of Radiation Progratns (OnP) has established tho
HEP to assist the; States in evaluating mitigation approaches for
reducing elevated indcor radon ! ©vci! e . Eighty HEP houces have
been avaluated in Penr.sy 1 vania nnd are currently being mitigated
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through Pennsy1vanin'a Department of Environmental Recourcss
(OER) Radcm Gas Damovistrntion Project as discussed below. MEP
projoctis hciva steo begun in How York, Ken Jerssy, and covsral
other stntss.
Mitigation information gained from IIPA's research has boon
conveyed to thrs public through brochures (1,2) and a technical
manual £3). Workshops, conforoncec, and interviews with tha
raedia also provide oltlgation information to the public.
- ,'J I
In responsQ to tho identification of l.ocr,iEizQd radon "hot
spots™ aany states have also dovoloped radon programs. For
©soaple,, the Daportaont of EnvireiiPenta) ?ro\oction (DEP) and tho
Departcc-nt of Health (DQH) in Mow Jsraoy bega» to davalop ths New
Jsrsey Kndon Prograo in 1985. The major coraponentu oi? this
progra® includet public inforraatlon programs, a statewide
scientific study of radon, epidemiological Gtudiats, con?irnatory
monitoring for houses with initial screening Isvels of iAS
bracquerelc par oubic mater (Eq/ci ) or greats?, voluntary firta
certification, a clustor Identification program, remediation
foisesroh, consulting for ncn-rosidential buildings, development
of a radon registry, and the tiavolcproent of a low interest loan
progr&a for tho funding of rs.don roaadiation. (personal
oonraunioation with Jou Hwang of DEF and Scfarancra <&>. Mew Jcrsoy
hacs also worked with EPh in the rersodi/sti on of houses in Clinton,
Mow Jepsjey, and tho State is jointly supporting a detisilcjd
rosearch project Sn tha piedmont rogien of Mew Jersey with EPA
and tha U. S. DapDrtuant of Energy.
Pennsylvania h££ also developed s radon program sines tha
discovery of elevated ration IqvoIg in the Heading Prong area of
the StEtQo The offorts of Pennsylvania's DE3 includes frqq
follow-up testing of houses with initial screening ievsla greater
there 7$0 frso post-raiti gaiion tasting for hoaiQOwnar3 who
how© inslaS Set? aorae; substantial reseadiatiorf work, and tho
initiation of a nuraber of pilot study prograraa with free
screening within tha geographic sraa of the study (5). DSS hast
also cenpilod data on private mitigation practices ir> over 200
houstss in Pennsylvania ac part of their post-mitigation surveys.
The 60 houses in Pennsylvania evaluated under EPA'd HEP,
together with an additional 25 houses, aro currantly being
mitigated as pert of Pennay I vania" s DER Radon Gas Daiaonstrutlon
Project. Of these 105 houeesj 72 hava radon rstnssdiation syctep.G
designed. To dote, 43 of these houses have been ecmpletely
rooi&diatcid (personal communication with Tin Hartfaan of DER).
RADON KITIGAT10M IN THE PRIVATE SECTOR
Fnforciation on mitigation practices in the private sector
was collected from three primary sources, an OP.P pilot survey of
radon mitigation firms, Pennsy1vania's DER pest-mitigation survey
of the private sector, and a 457-hov.'3G remeriiotion survey by tho
New Jersey DEP.
2
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ORP recsntly completed a pilot ourvay toy contacting nolected
contractors who have perforfnod oKteneive mitigation work in tha
privato sector. The aurvsy respondents havo perforraod raltigstion
in over i,400 houses in Connecticut, Dslriware, tho District of
Columbia, Maryland, Now Jarnoy, Mew YcirU, Pennsylvania, and
Virginia. Responses to the? survey t®nd to be taore qualitative
than quantitative sines most firss us'-i.-tiy do not keep dotal Isd
reoordn of thoir mitigation insto2 lations. Most-of the firms:
have bscn in the radon remediation field for a year or tMof and
70S of tlso respondents obtain information on radon raraodiation
from EPA, State agencies, trads publications and Boatings, end
their associates (6).
As mentioned abovs, the Pennsylvania DER has compiSod data
on more than 200 Mitigation installations in the privato (sector
of Pennsylvania aa part of tho Sisfco's follow-up testing for
homeowners who hove completed ooae substantia! remediation (5>.
The information available from this ourvay £b Molted to
mitigation technique, parforsianco, and cost.
The New Jersey DEP has alco collesctod data on radon
reduction inctalSmtionc in the private eactor. Data on
aitigation techniques inatallod and prs- isncl post-aitigation
ranges of radon concentration ara ooapilad for 457 houses in Mew
Jersey (perocnsl communication with Jcu Hwang of DEP).
PRSMtTlGATlOM DIAGH0ST1CS
SosQ dragroQ of diagnostic tsoting is usually porforsad prior
to selection antf design of a mitigation installation. Although
tho csstont of pi-crjitigation diagnostics verieu between EPA's
fiold projects,- certain diagnostics are applicable to oaeh
project: detailed visual inspaction off houss specific
characteristics and construction, identification of potential
radars ontry points, taaasuremont of substab/wall sir flow
comauniciition, racasursraent of deprssaurization due to appliance
usage, analysis of various soil characteristics, detoraination of
building material and/or wator as a radon source, end the
measurement of integrated radon levels prior to litigation.
Pretni t i gat i on diagnostics such as GsoEureisant of sir infiltration
rotes using a blower door or tracer Banco arc? often also included
to gain additional information about tbo house.
Twenty-four contractors ara ectiveiy participating in
Pennsylvania's Radon Gas Demonstration Project, and spacific
preoitigation diagnostics vary between contractors. In general,
diagnostics include n detailed viGual inspection of the houss and
measurement*; of eubslsab cnmmunlection if subclob ventilation is
being considered as a mitigation option (porcona! coEiaunicaticn
with Tim Hartman of DER).
Diagnostics generally performed by privato firiao rasponding
to ORP's pilot curvoy include determination of initial radon
levels or confirmation of homeowner providod measurement results,
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details of houatt construction and stylo, HVAC (hocting,
ventilating, and &.L r conditioning) infomation, and determination
If water So a pefcantial radon source. If subslab ventilotion is
faoing cotinidored as a aitigation option^ scso of th© firms tost
subalab coEsunication by drilling holoe and uoIrq d tracer gao
while otherra rely on espertenee with Gioilcr housos. Sonso firtaa
in tho pilot ourvay note the presence of applianeas that could
csusq houso tiaprostmrisailon or affect tho aircuiatiovt of Jridoor
air, and acEcitiuos inf or met Son on houso ago and occupant activity
is collected <6).
HITIGATION TECHNIQUES
Mitigation insta1lotiona £n EPA'o davalopoent and
daaonctration projects &ro usually phased, and often involvq
testing of cora than one techniquo or combination of tochniquos
in a given house. Both final and intorcsodiatffl inatallationn raro
discussed bo Sow, although-it ohould b© notad that intarEsodiate
phaGQrt aro ofton installed for rocoarssh purposes, and thoir
perforaancsr: tsnd to be lower than for the final oitigaticn
installations. It should eloo bo oaphacS^od that tauch f£ol«2 uoi'li
is currently in progro3c, and th® information preoontod in this
papor rsprouonta EPA uitiRation imstall&tSonr: to dots.
Figure 1 fjhoHu tha r-elativ© pra^oontaQOB ffer choice at
mitigation technique for tha S4 final installations for the f?,oid
projects located in Eastarn Fonnoylvanlc end Clinton and piodoont
Nou Jorooy. Mitigation involving oetivs sail gnu vents letJ on is
clearly thi? emphasis, eoapricing over C051 of th.^r:© techniques and
coobinatione of tochniquos. Nearly 7Sfl cf th© inotallntiono
ore subsiab ventilation oithor alone o? £n combination with
anotho*1 tochniquo. The raost prevalent cqgsM nation of mitigation
techniques £s cubs fab rand wall ventn ©tJon. Altltough sealing is
often involved in the coil ventilation inutallotiorss, sealing as
a technique by itsolf was not ueod in any of tho final
installations. Ncfco that crawl cpaco venti1stSon under
polyothyluno io included under eubalab ventilation for tho EPA
field projects. To a loGsar d&greo, ventilation using an air-to-
air heat enchanter (AAHX) end treatment of rndon in wator have
baon inotnllod as final raltigation inntallations in EPA®s field
projects.
The relative distribution of tho 24S inrtallatlonc to date,
including both tha final and tho Jntorraodiato installations in
EP(\*g field projects, is sinilar to that of the final
in3tal1 nitons diacunaed abova. Againt meet of tho installations
involve activo soil gas ventilation with oubolab ventilation
installed aiost froquontly. Mitigation toehniejuss sloo ctudiod in
tho interoedinte phases of installation inolutHo incroosod house
ventilation using an AAH3I, troatment of radon in unter, house
prssEtur ization, ana Dealing as o technique by itcolf.
Tho emphasis of EPA'3 Pennsylvania and Now Jersey fiolcS
projects discussed above has boan on techniques involving active
4
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soil gas ventilation, apsoSf icc>! !y aubsl&b vent i ! at i on. This
emphasis wag due largoly to Initial radon levels as high as
55,500 Bq/n encountered in tha3e early projects and tho
familiarity with and confidancs irs coll ventilation techniques in
reducing thnso high rodon levels. Current EPA field projects in
New York, Maryland.' Florida, Alabama, Tmnnasaes, and Ohio are
focusing on th« rraraediation of houses with lower radon levels
<370 to £650 Bq/a > that nationwide prosent a greater public
health risk. In addition, aoro divers® and lower cost aiti gat I on
techniques ara bIgo being actively investigated. Those? include
control of houae preusuro, senling, and passive soil gas
ventilation.
To date, A3 houses, including QRP'g HEP houses, have boon
raitigatod in Pennny!vanta's Radon Gas f)enonstration Project.
Since mitigation is r.till in progress, specific installation
information is not available at this tlno. In general, subslab
ventilation has been the preferred mitigation technique. Scaa
installations have included several phases of mitigation, ar.d
techniques such as sealing, isolation, arid prossurizatlon have
also boon installed (personal cocarauriicat ion uith Tin Karttnan of
DER).
Firms responding to tho ORP pilot survey almost always
install phased mitigation techniques beginning with the simplest
and iaast ess:pegsi vo. I i the initial radon oeriesntration is loss
than 740 Eq/ts the firnt phase often Invoiwss the e&uiklrtg r*nd
sealing of all cracks, and penetrations in contest with
the soilB cowering a.~.
Many firms responding to the pilot eurvc?y indicated that,
because of fchc'lr high lovel of confidence, oubslab ventilation
systerao are soraotiraa:; installed to^mitis&te relatively low radon
concentrations (less than 370 Bq/c ) due to a pending real estate
calo. In fact, tha contractors interviewed cito real eatate
salsa ac sources of 20'.1S to 0054 of tbsir business (6).
Private eector ssitigation choices compiled from DER's post-
mitigation survey arc shown in Figure 2. Mitigation techniques
involving active soil ventilation are rsost prevalent, comprising
43W of the installations. Subclab ventilation la the most common
technique in the post-nil tljRation survey, although seeling and/or
passive house ventilation are also popular choices. Many of tha
contractors elao chose to install an AAHX.
5
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The radon reduction tsoosurco inpioisen'ced in 457 houses in
Mew Jorcoy ara ohowt? in Figure 3. Subs3ah uonti Icition is the
raost coq3o:i technique cRapriafng 30Tj of tho inat&i!at£cr.c.
Sealing ss*' the sucip hole; and/or French drains, inatal lation o£
AAMXs, and sualins of cracks ara bIijo pr&v&lent rauadiaiion
laaocures in Mew Jeraay (personal cocmunicailcn with Jens Huang of
DSP).
APPLE C£7iGN OF SI 5 TJ GAT J OK TECHNIQUE TO SUBSTRUCTURE TYPE
EPA bins dovolopad a radon toot laotriK to holp dofcex-cain® tho
nutsbor off eubntrusturo typos that Mil! toco to b® tested with
®ach rc.don roduction technicgua. Substructures aoet typical of
the U.S. houKing ntock ore vocoiving esshanirej to dstoe 24G
litigation techniques ond ccs-'Mnations of techniques tuw© bean
installed in the first SO of EPA's field project houses. Two-
thirda of the houses aitigatod thus frr are block baseraent or
combination basrasiont and si ab-on-grode Bubctructuras. Other
substructures studied includa: poured cuncreta ba3c»Konts, slab-
bo 1 ovj-grado, crsul spneo, and consbinationss of baaeaenta, slabs,
ane* crawl spacoc. Crawl epdcg, s Isb-sn-gradc, stone baserssnt,
and carabi net ions of '.U& above substructures aro also receiving
emphasis in f£old projects ?«eontly underway*
Subc^cuetuvQ inforcziticn in not currently available fur ttiQ
houaoa ursdor study if; Penney I vnrsin® s Radon Gas Ceeovctration
Project or Dii£i*« ponv.-'^itiaatf.ovfs Ktirvoy oil privsfca soctor houces3.
float privnto coctor contractors ranpondirg to tbo pilot
nurvey did liot Uscp dc-tailcd records portainisic to substructuvo
typo, Contractors repcrtad that at Icr&st QQK of tha houses
mitigutod had bassoents with c.Iaba nna oitStnr bioci; or poured
walls depending tin construction practxco in Iho arsa. Crs>wi
apfjcos uara aitigatod by SS to iOG of the fiptan £S>.
PERFORMANCE OF MITIGATION INSTALLATIONS
Tho perfarsiancc ranges of fins! nitigation installations in
EPA's fiold prajnetc are shown in Figur© 4. Perforaanoes of
techniques involving soil gas venti lotion were taost successful,
ranging frjro 65% to nearly 100£ radon reduction, corrasponding to
radon concentrations of 37 to 777 Bq/a .
For the 6-3 houaoG completely romadiotod in Pennsylvania's
Radon Gas DauionGtration Project, p»rforinanceis ranjiad from 90SS to
100K radon reduction, corrccpond^ng to pont-aitf.cat.ion radon
concantrations of 22 to i04 Bq/a for all typos of mitigation
techniques installed.
Most of the> nitigction firrjB contracted for th« pilot survsy
do net Bui'-ce post-mitigatiori rcdon measurements duo to potential
conflict of Sntorast; consequently, it. is often difficult for the
firms to koop d&tailod records of mitigation perfonnanoo. In
6
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genera! , tf>a firtao reported th&t aehfov© radon 1 avoirs belou
EPA* s recoDitiantied lovol (148 Bq/a ) SOTS off the titrjo with subs lab
ventilation (tJ).
Per? orrannco data for DEfi's post-ui iifjufclan survoy of private
Hector inct&l lationE ere ohawn in Figure S. Do not placo too
much emphasis on ainicium and oaKiaurj pos-sent reductions: various
Beans of tastinc wore often used, and pro*- and post-raitication
testing tcchniquao are not atwayo sinilaif. Parforaancas for
active soil ventilation ranged I roa i£>£ to S815 rsdustiont the
nout Eject cotaEon technique, scaling ftnd/or paB&iv© house
ventilation, exhibited a performance rango frora an increase in
ration to 07% reduction.
Detailed data rotating porformanco to Dpocific technique aro
not available for this New Jersey DEP study; hewevor, tho porcont
of houses in various post-mitigation radon conosntration rangos
are shown in Figure 6. Of these houeos, 70S exhibited po3t-
jiitigntion radon^ concentrations exceeding £48 Bq/o , and 3Qt>
sKcoedsd 370 Bq/m .
ESTIMATED COSTS OF MITIGATION INSTALLATIONS
The estior-ted costs of various ration o£t£gaticn teehnicjuso
aro ehoun Sn Tab 5 a i. Tho Goyoi-naoRt ostJontos for coc'cs a$
aitigotion tend to cover a t^idor ptrngo rsn&i csuDOHltat hicho?
than pirivato sector costs. Th© highos- eecta s.i-o (Jug in le.rtfo
part to the rscearch data ccllestGd and additional ovorhc&d costs
incurred in govGrjiuiRnt sponsored nitigation.
Table? 1. EstStaetod Coats of ftc-rion Kiftination
'litigation
Technt quo
Dvorall Avorage
Active Soil I'mt.
*AHX
jiraplo House Vent,
jooling
Initial EKpeirtcoa CS3S7 U.S. dol Iqt-j)
eea
MA
1050-5200
2700
400-600
550-3700
Govornaont
a
Sealing Crawl Space
NA
amk
4329
NA
NA
NA
NA
NA
Privates Sector Surveys
egs~
ORP
500-51500
400-2500
12C0-3000
NA
50-1500
100-500
1000
NA
NA
NA
MA
NA
ORP'a OBtimpted cor.ta for radon
to an annual average
crayS upaco, and filab-on-
reduction
of 146 Bq/m^ in houses with basosent,
grade substructuroc
Average cost per installation (persona! coEBunicntion with Tim
Hartman of DER)
Estimated alligation co-jito frora pilot survey respondents (6)
Approx iinata average tni ti gat.ion cost for DEF? post-mitigation
survey <5)
7
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CONCLUSIONS
A comparison of government and prlvata sector radon
aitigatlon in the U. S. yields the ?ollr>u-ing conclusions:
Available inforaiation on precsi tigation diagnostics indicates
thst both the public and private sectors collect detailed
house characteristic information,. and usually measure
Bubslab coninuni cation; howtrvur, Federal government
sponsored raitigation tends to collect qo?g data for research
and dcvslopnor.'t purposes.
Subnlab vantilotion is the most coascn mitigation technique
in both the pvblic and private soctorc. AAHXs and sealing
ai-o employed more frequently in th» private sector than in
governaent oponsoyed faitigation.
Maitimuia performances of mitigation techniques are sirailar ir»
both the pul ,ic and private sectors;; however, miniotuo
percent reductioris are difficult to compare due to varying
initial radon levels. Performance data on private sector
mitigation, compiled by the State of N»u Jersey, indicate
that a large percentage of mitigntion instiil'ations^do not
reduce indoor radon concentrations to bslow 143 Bq/ss .
Although it is dii'ficult to eonpare cost dr.ta without
knowing more detailed infortEwtion, coat eci'DntQs tsnd to bo
lowor for the private sector than for ?ove».muent sponsored
incta1 lotions.
REFERENCES
1 U. S. EPA, A C£ 1.1zqn'1; To. i t 1 a and t-fhrat
To Do About 11. GPi\~G6-004, Auguat 1S36.
2 U. S. EPA, Ration deduction Methods; A Har.eovinar' n Guide
(Snconri Edition). DPA-Q7-010, September x887.
3 U. S. EPA, Rodon Rt?duct 1 on Techniques for. Detnchad Houses.
EPA/4525/5-86/019, June 19G6.
A Nichoils, G.A. and D.A. Deioso, "New Jersey Involving the
Cooinercial Sector," Environment. Vol. 29t No. 2, March 1987.
5 Rittiger, C.L. , *:Mi ti gat ion in Practice," presented at the
19th Armur> 1 Conf erencr or_\_ Radiation Contro 1 in 3oi go, Idaho,
Hs.y lGfl7.~
S Cohen, S.A., ^R^nujtc of a Pilot Survey of Radon Prevention
and Mitigation Firms," U.S. EPA, Contract No. 68-02-4375,
November 1907 (Draft).
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