A study in the BMJ has found a significant reduction in the incidence of myocardial infarction (MI) since smoke-free legislation was introduced in England on 1 July 2007.There have been many studies including meta-analyses showing that passive smoking increases the risk of coronary heart disease and this risk could be increased by as much as 60%, similar to that seen in light smokers. The mechanism of such effects is thought to be through increases in platelet aggregation and alterations in endothelial function. These effects can occur very rapidly and as such the benefits of reducing smoke exposure could be seen quite early.