Figure 1.

Respirable elemental carbon (REC) metrics, Diesel Exhaust in Miners Study (DEMS), United States, 1947–1997. The solid line shows a metric derived in part from extrapolated carbon monoxide measurements, as developed and used by Attfield et al. (1) and Silverman et al. (2) (DEMS_REC). The dashed line shows a metric derived from diesel engine horsepower and mine air ventilation, without extrapolation from carbon monoxide measurements, as developed and used by Crump et al. (10) (ALT_REC). A) Mine A, limestone; B) Mine B, potash; C) Mine D, potash; D) Mine E, salt (halite); E) Mine G, trona; F) Mine H, trona; G) Mine I, trona; H) Mine J, potash.