From: Outdoor air pollution and terminal duct lobular involution of the normal breast
 | All women | Premenopausal | Postmenopausal | |||
---|---|---|---|---|---|---|
N | RRa,b (95% CI) | N | RRa,b (95% CI) | N | RRa,b (95% CI) | |
Cluster | ||||||
 1 | 31 | Ref. | 18 | Ref. | 13 | Ref. |
 2 | 1058 | 1.82 (1.13, 2.93) | 750 | 1.64 (0.96, 2.80) | 302 | 3.30 (1.17, 9.28) |
 3 | 815 | 1.74 (1.08, 2.80) | 554 | 1.56 (0.91, 2.68) | 259 | 3.33 (1.19, 9.35) |