Table 4c: Years of exposure by year first exposed for which a lung cancer case is "more likely than not" due to radon progeny exposurea, based on probability of causation exceeding 0.5. Estimated relative risks are increased to incorporate statistical uncertainty at the 90 percent level.

Years since last radon progeny exposure

Smokers

Non-smokers

Age at disease

<10

10-19

20

<10

10-19

20

First exposed: <1955

<50

0.0b

0.00

0.0

0.0

0.0

0.0

50-59

0.2

0.3

0.6

0.1

0.2

0.3

60-69

1.1

1.6

3.4

0.5

0.7

1.5

70

1.7

2.6

5.5

0.7

1.1

2.4

First exposed: 1955-59

<50

0.0

0.0

0.1

0.0

0.0

0.0

50-59

0.2

0.4

0.7

0.1

0.2

0.3

60-69

1.4

2.1

4.3

0.6

0.9

1.9

70

2.2

3.3

7.0

0.9

1.4

3.0

First exposed: 1960

<50

0.0

0.1

0.1

0.0

0.0

0.1

50-59

0.6

0.9

1.9

0.3

0.4

0.8

60-69

3.6

5.5

11.5

1.6

2.4

5.0

70

5.8

8.8

18.5

2.5

3.8

8.0

^a Model used in the model to compute PC=0.5, RR = 1 + ß × d × Ý_yfe × tsle × age × t^{(age - 60)} with time since last exposure, and year first exposed defined by categories. For calculations, in Table 2 is replaced by ×exp[1.64×SE( ß)] then adjusted to ß_smk or ß _ns as described in the text. For computing RR with age categories, mean ages 44.5, 54.8, 63.9, and 75.7 used.

^b A value of 0.0 years exposed denotes exposure to radon progeny which is less than 0.05 years (or 0.6 mos = 0.05×12, or 102 working hrs = 170×0.6)