Figure 1.

Lung cancer hazard ratios against 15-year lagged cumulative respirable elemental carbon (REC) exposure (μg/m³-y) for ever-underground workers, for all tenures, and after excluding workers with less than 2, less than 5, and less than 10 years tenure at time of event (see Table 4 for <5 year exclusion results). Analyses were performed with the Cox proportional hazards model and probabilities determined with a two-sided χ² Wald test.