Objective To determine whether there was a change in hospital admissions for acute myocardial infarction while a local law banning smoking in public and in workplaces was in effect.
Design Analysis of admissions from December 1997 through November 2003 using Poisson analysis.
Setting Helena, Montana, a geographically isolated community with one hospital serving a population of 68 140.
Participants All patients admitted for acute myocardial infarction.
Main outcome measures Number of monthly admissions for acute myocardial infarction for people living in and outside Helena.
Results During the six months the law was enforced the number of admissions fell significantly (- 16 admissions, 95% confidence interval - 31.7 to - 0.3), from an average of 40 admissions during the same months in the years before and after the law to a total of 24 admissions during the six months the law was effect. There was a non-significant increase of 5.6 (- 5.2 to 16.4) in the number of admissions from outside Helena during the same period, from 12.4 in the years before and after the law to 18 while the law was in effect.
Conclusions Laws to enforce smoke-free workplaces and public places may be associated with an effect on morbidity from heart disease.