RADIATION (RADON)

Elderly persons, lifetime exposure

Damp

Vulnerable age

Related hazards

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

After improvement - extract vent

C) Front living room & spine wall

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

A

-

Seriously defective

Defective

Not satisfactory

Satisfactory/NA

Key

3

2

1

-

DESCRIPTION OF HAZARDS

Dwelling: 1930's semi-detached house

Background: This is a 3 bedroomed semi-detached house built around 1930 in a radon affected

area. It has solid 9 in brick external walls which are rendered and all of the ground floor rooms have

suspended timber floors. The house is centrally heated but there is an open fire in the living room.

Suspended timber floors: The floors to the ground floor front and rear living rooms, kitchen and hall

are all of tongued and grooved timber boards laid on joists, with a relatively shallow underspace

below. Measurements show a radon level in the house of 800 Bqm-3.

A)

LIST OF RELEVANT MATTERS

LIKELIHOOD & OUTCOMES

A

a

Timber ground floor

3

b

Disrepair to solid floor

-

c

Lack of DPM

2

d

Sealing around services

-

e

Ventilation rates

-

f

Open fires

2

g

Remedial measures

-

h

Extractor fans

-

I

Private water supply

-

# Secondary hazards

-

None

A B C D E F G H

I

J

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

in all dwellings, following lifetime exposure

162

HHSRS VERSION 2

SEPTEMBER 2004

HEALTH AND SAFETY RATING SYSTEM SCORES

1920-45 House

LIKELIHOOD

1 in

320

Low

High

Average: 10,000

Example

320

< 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

There is sufficient evidence to suggest a radon problem and subsequent measurements

show a level of nearly 800 Bqm-3, substantially above both the average for radon affected

areas and the recommended action level of 200 Bqm-3. Information from NRPB and

other sources (see table overleaf) indicates that this would give an annual risk of cancer

of around 1 in 280.

%

90.0

10.0

0.0

0.0

Score

Average: 90.0

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

< 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 rounded up to

1 in 320, this average spread gives a score of 2843 and a rating of band B.

Average: 91

F G H

I

J

Example

A B C D E

Score

2843

RATING SCORES AFTER IMPROVEMENT

IMPROVE

Justification

NEW RATING

Av: Nos

Likelihood to

1 in 5,600

Outcomes to

90.0 10.0 0.0

0.0 %

In this case, the installation of underfloor mechanical extract ventilation is found to reduce

the radon level to 40 Bqm-3 and thereby the likelihood to some 1 in 5,600 and the rating

score to some 160. Thus, the rating band is reduced from B to F. As the dwelling is in a

high radon gas risk area, some risk remains.

Improved Av: 91