Background This study aimed to determine the number of latent smoking trajectories among Canadians employed in the workforce over a 16-year period, and if latent trajectories in dimensions of the physical and psychosocial work environment were associated with specific smoking trajectories.

Methods We studied 5461 employed adults from the longitudinal Canadian National Population Health Survey. Daily cigarette consumption was measured biannually from 1994 to 2010. Work environment factors (skill discretion, decision authority, psychological demands, job insecurity, physical exertion and workplace social support) were measured in 1994 and then from 2000 to 2010 using an abbreviated form of the Job Content Questionnaire. Smoking and work environment trajectories were derived using group-based trajectory modelling. Associations between work environment trajectory classes and smoking trajectory classes were estimated using multinomial logistic regression.

Results Four latent smoking trajectories were seen: non-smokers; ceasing smokers (consuming ~14 cigarettes/day in 1994 and 0 in 2008–2010); smokers (consuming ~7 cigarettes/day between 1994 and 2010); and heavy smokers (consuming ~22 cigarettes/day in 1994 and ~14 in 2010). Lower skill discretion, high psychological demands, high physical exertion and low social support trajectories were associated with membership in the heavy smoking trajectory compared with the non-smoking trajectory. Low decision authority, high psychological demands and high physical exertion trajectories were associated with membership in the ceasing compared with the non-smoking trajectory.

Conclusions Certain physical and psychosocial work environment trajectories were associated with heavy and ceasing smoking behaviours over a 16-year period. The role of the work environment should be further considered in smoking cessation programmes.