Background and objectives-To examine the long term impact of workplace smok
ing bans on employee smoking cessation and relapse. Over three years we stu
died a total of 1033 current or former smokers (intervention group) employe
d in smoke-free hospitals and 816 current or former smokers (comparison gro
up) employed in non-smoke-free workplaces. The design of this natural exper
iment is a prospective cohort study. We randomly selected both hospitals an
d employees from 12 strata based on hospital size and state tobacco regulat
ions, and sampled employees in the same communities. Main outcome measures
were post-ban quit ratio and relapse rate.
Research design-Between groups comparisons were conducted using the Cochran
-Mantel-Haenszel statistic for general association, stratified Cox proporti
onal hazards models, and the CMH analysis of variance statistic based on ra
nks. McNemar's test and the sign test were used to test for changes over ti
me within each group.
Results-Differences in the post-ban quit ratio were observed between interv
ention and comparison groups (p less than or equal to 0.02). For employees
whose bans were implemented at least seven years before survey, the post-ba
n quit ratio was estimated at 0.256, compared with 0.142 for employees in n
on-smoke-free workplaces (p = 0.02). After controlling for a variety of fac
tors, time to quit smoking was shorter for the hospital employees (p < 0.00
1), with an overall relative risk of quitting of 2.3. Contrary to expectati
ons, relapse rates were similar between the groups.
Conclusion-Employees in workplaces with smoking bans have higher rates of s
moking cessation than employees where smoking is permitted, but relapse is
similar between these two groups of employees. The results of this investig
ation have international applicability for policy makers, clinicians, emplo
yers, and employees. Countries should review smoking policies in workplaces
in light of their own smoking patterns and efforts to deal with environmen
tal tobacco smoke.