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.