RADIATION (RADON)

Vulnerable age

Related hazards

Elderly persons, lifetime exposure

Damp

HHSRS VERSION 2

SEPTEMBER 2004

HHSRS VERSION 2

Multiple locations

Yes

No

Secondary hazards

Yes

No

Front elevation

Radon/rating table

Radon

Likelihood

Bqm-3

1 in

Rating

score

Elevation of terrace

C) Solid floors and cavity walls (illustrative only)

Rating

band

B

C

D

D

E

E

F

800

277

3,285

400

518

1,757

200

1,000

910

150

1,322

688

100

1,961

464

50

3,902

233

25

7,853

116

DESCRIPTION OF HAZARDS

Dwelling: 1970's mid-terraced house

Background: This is the centre house in a terrace of five two storey houses built on a steeply

sloping site in an area of the South West with generally high radon levels. All the houses in the

terrace are affected by the gas but to varying degrees, the larger end houses having the highest

levels. The centre house of the example has the lowest level in the terrace and with a radon

measure of 196 Bqm-3, falls just below the radon action level. The other houses in the terrace

have levels of 914, 739, 226 and 2,274 Bqm-3.

Solid floors: All the ground floor rooms have solid concrete floors. Built before radon protective

measures became a requirement of the Building Regulations, all floors have a damp proof

membrane but this of an insufficient specification to stop the ingress of radon gas around the joints

with the walls and pipes and via the cavity walls.

C)

LIST OF RELEVANT MATTERS

LIKELIHOOD & OUTCOMES

A

A

a

Timber ground floor

-

I

Private water supply

-

b

Disrepair to solid floor

-

c

Lack of DPM

1

# Secondary hazards

d

Sealing around services

3

-

None

-

e

Ventilation rates

-

f

Open fires

3

g

Remedial measures

-

Key

3

Seriously defective 1 Not satisfactory

h

Extractor fans

-

2

Defective

- Satisfactory/NA

Improved

A B C D E F

90.0

< 0.05 0.15 0.3

0.7

1.5

3

7

15

26

38 >

Av: 10.0

10.0

< 0.05 0.15 0.3

0.7

1.5

3

7

15

26

38 >

Av: 0.0

0.0

< 0.05 0.15 0.3

0.7

1.5

3

7

15

26

38 >

Av: 0.0

0.0

Average likelihood, outcomes and HHSRS score for radon for persons aged 60 to 64

years in all dwellings, following lifetime exposure

HHSRS VERSION 2

SEPTEMBER 2004

HEALTH AND SAFETY RATING SYSTEM SCORES

1946-79 House

LIKELIHOOD

Low

High

1 in

1000

Average: 10,000

1000

< 4200 2400 1300 750 420 240 130

75

42

24

13

7.5

4

2.5

1.5 >

Justification

OUTCOMES

Class I

Class II

Class III

Class IV

Justification

RATING

Due to the location of the terrace and its date of construction prior to the introduction of

relevant Building Regulations, there is sufficient evidence to suggest a radon problem

and subsequent measurements show a level of 196 Bqm-3 in the example dwelling.

Information from NRPB and other sources (see table overleaf) indicates that this would

give an annual risk of cancer of around 1 in 1,000.

%

Average: 90.0

90.0

10.0

0.0

0.0

Score

162

< 0.05 0.15 0.3

0.7

1.5

3

7

15

26

38 >

The radon level does not alter the spread of outcomes. With the likelihood at around 1

in 1000, this average spread gives a rating score of 910 and Band D.

Average: 91

G H

I

J

Example

A B C D E F

Score

910

RATING SCORES AFTER IMPROVEMENT

IMPROVE

Justification

NEW RATING

Av: Nos

Av: 91

G H

I

J

Likelihood to

1 in 5,600

Outcomes to

90.0 10.0 0.0

0.0 %

The high values in the terrace generally suggest a communal solution with two

externally excavated sump systems fitted one at either end of block. This reduces the

radon level in the centre house to 25 Bqm-3 (and in the other houses to 13, 13, 21

and 13 Bqm-3).