INTRODUCTION SMOKING Of all the risk factors for heart disease, the ones overwhich an individual has the most control are thoserelated to “bad habits,” namely the use or abuse oftobacco (especially cigarettes), alcohol, and illicitdrugs. Numerous studies show that people who usethese substances have a marked increase in risk of developing heart disease. Still, there is hearteningnews for longtime smokers, drug users, and heavydrinkers who quit The increased risks can be loweredand even eliminated.

The benefits of controlling or, better still, elimi- nating these risk factors can be dramatic. In fact,smoking cessation is the single most effective stepthat smokers can take to lower their risk of heart disease. Former smokers live significantly longerthan do continuing smokers, and-their reduced in-cidence of heart disease is one of the major reasons.

This chapter reviews the dangers of smoking, drinking, and using illicit drugs. The ways in whichthese habits raise the risk of heart disease and meth-ods for quitting or moderating consumption are alsodiscussed. The chapter also reiterates a key theme,namely, that quitting can lower the risk of the de-velopment and progression of heart disease, even af-ter decades of use.