Table 3.

Ischemic heart disease hazard ratios and 95% confidence intervals associated with cumulative years of work in each major job title

					Hazard Ratio for 20 yrs of work
Job title	Person years	Ischemic heart disease deaths	% change in relative risk per year of work	Smoking adjustment factor*	Multivariate†	Smoking Adjusted‡
Long haul	216,019	626	4.2 (−0.9, 9.8)	1.04	2.32 (0.84–6.44)	2.23 (0.80–6.18)
P&D	228,961	369	3.7 (−1.4, 9.2)	0.92	2.09 (0.75–5.82)	2.27 (0.81–6.32)
Dockworker	295,369	352	3.9 (−1.2, 9.5)	1.04	2.20 (0.79–6.13)	2.11 (0.76–5.89)
Combination	165,151	201	3.2 (−2.0, 8.7)	0.98	1.89 (0.67–5.30)	1.93 (0.68–5.42)

^*Job-specific smoking adjustment factors were calculated by dividing the smoking weighted risk for each job by the smoking weighted risk for workers not employed in that job.

^†Multivariate hazard ratios using regression coefficients from Cox proportional hazards regression models stratified on age in 1985, decade of hire, and calendar time, with risk sets by attained age, adjusted for the healthy worker survivor effect (total years on work, years off of work) race, Census region of residence and the 1985–2000 average ambient PM₁₀, NO₂, and SO₂ values at the last known residential address.

^‡Smoking adjusted hazard ratios are calculated by dividing the multivariate hazard ratio by the appropriate smoking adjustment factor. The 95% CI were calculated by considering the sampling error in calculating each job-specific correction factor.

Note: Each worker could potentially accumulate exposure in multiple job categories throughout his career.