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(1)

Preventing Radon Exposure

Radon Control In New

Homes: A Meta-Analysis of

25 Years of Research

William J. Angell

Professor and Director

(2)

Overview

Importance of Radon Control in New

Houses

As documented in a 2008 paper I authored,

the U.S. has more

housing units with elevated radon than anytime in our history

– The major reason for this problem was that in a typical year more new

homes were built that had elevated than the number of existing

homes that mitigated

This situation is also true for the vast majority of the world

• It has been demonstrated that, in many cases, a public sector

emphasis on radon control in new housing was more cost-effective

for population-based risk reduction than a testing/mitigate

approach

(3)

Overview

Basic Radon Control Strategies

• Passive sealing only

For example, subslab membrane

Focus in the UK and Ireland

• Passive soil depressurization

Permeable subslab layer, soil gas vent riser through conditioned portion

of the house and terminating above the highest roof, thorough sealing

of soil contacted foundation elements

Historically, the focus in the U.S.

• Active soil depressurization

Permeable subslab layer, soil gas vent riser with an in-line fan through

conditioned portion of the house and terminating above the highest

roof, thorough sealing of soil contacted foundation elements

(4)

Overview

A Sample of U.S. Guidance Documents,

Standards, and Code

(1:2)

• U.S. EPA (1987)

Radon Reduction in New Construction, An Interim

Guide

• ASTM (1990)

Emergency Standard Guide for Radon Control Options

for the Design and Construction of New Low Rise Residential

Buildings

• Clarkin and Brennan (1991)

Radon-resistant Construction Techniques

for New Residential Construction (EPA)

• U.S. EPA (1994)

Model Standards and Techniques for Radon Control

in New Residential Buildings

• Council of American Building Officials (1995)

One and Two Family

Dwelling Code

(5)

Overview

A Sample of International Guidance

Documents, Standards, and Code

• Clavensjö and Åkerblom

(1994)

The Radon Book: Measures

against Radon

• Building Research

Establishment

(BRE) (1999a,

1999b) Construction of New

Buildings on Gas-contaminated

Land and Radon: Guidance on

Protective Measures for New

Dwellings

• Roserens, et al.

(2000) Swiss

Radon Handbook

• National Building Code of Finland

(Ministry of the Environment, 2003)

(6)

Results

Overview of Results

The total number of documents reviewed was 57

As reflected the following slide,

36 papers of the more data rich publications are summarized by

Author(s) and year of publication

Number of houses and number of communities in the study

Whether the houses were built according to EPA guidance or similar

codes

Radon testing details

Whether pressure differential measurements were reported

Types of radon control techniques used or assessed in the study

(7)

Results

Some Pivotal Papers

Pivotal documents included:

– Murane (1988)

describing data from 148 new houses in

EPA’s New House Evaluation program built by 5 builders in

CO and MI

– EPA (1999)

guidance document or protocol on measuring

the effectiveness of PSD systems

– Weiffenbach and Marshall (2003)

reported very extensive

data logging in 8 houses

(8)

Results

Radon Concentration by Foundation Type:

Finland

(Arvela, Holmgren and Reisbacka [2011])

Rn Concentration (Bq m

-3

)

Foundation Type

# Houses

Average

Median

Slab-on-grade

798

97

68

Monolithic Slab

18

36

27

Crawlspace

231

43

29

Semi-basement and Basement

193

161

97

No Information

321

89

54

Total

1561

95

58

These data are from a 2009 national random survey of Finnish

houses built between 2004 and 2006 when new building code

requirements were enacted

(9)

Results

Effects of Passive Methods in Finnish

Slab-on-Grade Houses

(Arvela, Holmgren and Reisbacka [2011])

These data are from a 2009 national random survey of Finnish houses

built between 2004 and 2006 when new building code requirements

were enacted

Passive Preventive Measure

None

PSD

Piping &

Sealing

PSD

Piping &

No

Sealing

Number of Houses

230

166

111

Average Rn Concentration (Bq m

-3

)

90

82

98

Median Rn Concentration (Bq m

-3

)

68

53

59

(10)

Results

Winter and Summer Rn Concentration

with Cap-on/Cap-off NAHB Houses

Winter

Summer

Stack Closed

192 (5.2 pCi/L)

133 (3.6 pCi/L)

Stack Open

93 (2.5 pCi/L)

67 (1.8 pCi/L)

Percent Reduction

52%

50%

The data in this table

– Reflects seasonal variation - stack effect in 22 houses with PSD

systems in 6 states

• But the similarity in percentage of radon reduction is notable

(11)

Results

PSD Cap-on/Cap-off Studies

The following table summarizes the findings of

12 studies of

radon concentrations in 224 houses with PSD systems

:

Capped (nonfunctional)

The average radon concentration was 231 Bq m

-3

(6.2 pCi/L)

Open (functional)

The average radon concentration was 127 Bq m

-3

(3.4 pCi/L)

(12)

Results

PSD Cap-on/Cap-off Studies

(Bq m

-3

)

Study (alpha order)

Number Houses

Cap-on

Cap

-off %

Notes

Brehm, 2002 20

105 93 -11

PSD compromised; 2 day Rn tests, location & season unspecified Dewey, 1994 Basement 44

196 81

-59

Basement Rn tests; 36 tested same season

First Floor 44

81 44

-46

First floor Rn tests; 36 tested same season

Average

139 63 -55

Fort Collins, 2006 65

296 148 -50

Houses built 2005; Rn tests length & location unspecified

Hagerty, 2003 13

344 278 -19

PSD compromised; 5-7 day Rn tests, season & location unspecified Hanson, 2005 8

244 125 -49

PSD compromised; January basement Rn tests; test length unspecified LaFollette, 2001 22

337 163 -48

7 day Rn tests on the lowest level suitable for occupancy

Najafi, 1995 2

252 257 +2

2 of 14 houses with PSD tested

NAHB, 1996 Winter 22

192 93 -48

PSD compromised; winter lowest level Rn tests; test length unspecified Summer 22

133 67 -50

Summer Rn tests in lowest level; test length unspecified

Average

163 80 -49

Saum, 1990 1

1110 278 -75

Cap-off approximate value; winter Rn tests

Snead, 2003 5

269 192 -25

PSD compromised; average 7 day winter Rn tests; location unspecified Tyson, 1995 15

88 94 +7

Main floor 48 hour Rn tests; testing season unspecified

Weiffenbach, 2003 7

366 161 -56

Basement, 6+ day, winter Rn tests

Total

224

(13)

Results

PSD versus ASD Radon Control in New

Houses

The following table summarizes the research findings of 9

studies on the

comparative performance of PSD and ASD

system in 61 houses

• Overall, ASD offers

– More than an 80% reduction in indoor radon concentrations in new

houses

(14)

Results

PSD vs. ASD Performance

Radon Tests (Bq m

-3

)

Study

# of

Houses

PSD

Capped

PSD

Open ASD

Notes

Brennan, 1988

2

270

250

30

Five day Rn tests, season & location unspecified

Clarkin, 1993

1

333

41

April-May, 6 day basement Rn tests

Dewey, 1994

13

250

161

60

Basement Rn tests

Keränen, 2008

14

630

130

Two month, first floor Rn test, seasons varied

Lewis, 1999

10

4735 555

Location, season & length of Rn tests generally unspecified

Najafi, 1995

13

81

53

Four first floor Rn tests, seasons & length of tests unspecified

Saum, 1990

1

1110

833

37

Location, season & length of Rn tests unspecified

Tyson, 1995

6

141

141

76

Main floor 48 hour Rn tests; testing season unspecified

Weiffenbach, 2003

1

1110

444

37

PSD Rn with poor sealing; ASD with sealing

Total

61

Weighted Averages

(15)

Results

New Construction Radon Control Standard

• RRNC (Reducing Radon in New Construction) 2.0

– American National Standard Institute (ANSI)/ American

Association of Radon Scientists and Technologists

(AARST) CCAH – 2013

• Written in building code language

• Rough-in or activation of a soil depressurization system

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